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                    of Diving Medicine Online
Scubadoc's Diving Medicine
Comprehensive information about diving and undersea medicine for the non-medical diver, the non-diving physician and the specialist.
Asthma and Diving
Asthma -  Divemaster?
Bad Air Problems
Asthma Inhalator

Bone and Joint
Knee Replacement?
Leg Strain?
Scoliosis ?

Decompression Sickness
Actions With Possible DCS
Elbow Pain Caused by DCS?
Can DCS Cause Strokes?
Risk of DCS After Knee Surgery?
Recover from Paralysis?
Chronic Back Pain?
Outcome of DCS Joint Pain?
Return to Diving Post DCS
Missed Safety Stop = Near Miss?
DCS - Joint Aches Years Later?
Do I Have the Knee Bends?

Dehydration and Diving?
What Caused My Dry Mouth?
Suck It Up: SCUDA
What Makes Me Pee While Diving?

Deep Water Blackout
Why Did My Buddy Black Out?

Dental Problems
Can I Dive After a Root Canal?
Diving with Dental Implants
Help! My Reg Makes Me Gag
Can Diving Cause Dental Problems?

Dermatological Problems
Fire Coral Scars
Seabather's Eruption

Diabetes and Diving
Can I dive with diabetes?
How can diabetes affect a diver?
So who can and can't dive?
Guidelines for diving with diabetes?
Tell my dive instructor about my condition?
What is Diabetes?
Diving programs for Diabetics?
Warning Signs of Diabetes?

Drugs and Diving?
Dive Medicine Tips
Benadryl Sedating?

ENT Problems
Trouble Clearing
Why Can't I Equalize One Ear?
Equalizing with Tiny Tubes
Blood in My Mask
What Is Causing My Sinus Problems Under Water?
What Caused My Nosebleed?
Frenzel equalization method
Can I Dive with a Cold?
Treatment for Middle Ear Barotrauma?
Diving and Tinnitus (Ear Ringing)
Can I Dive After An Ear Operation?
Can I Take Allegra and Dive Nitrox?
Prevent Ear Infections
What Do You Know About Star Otic?

Exercise and Diving
Exercise Affect My Diving Experience? Can I Dive After Running a Marathon?
Safe to Exercise After Diving?
Is Creatine Dangerous for Divers?

Eye Problems
Contacts Damage My Eyes
Keratoconus and Diving?

Fear, Anxiety and Panic
Diving, Fear of Fish

Flying, Altitude after diving?
Altitude and Diving?
Flying After Diving:  Rules
Diving after flying?

Free Diving
Free Dive After a Scuba Dive?

GI Problems
Diving on Hepatitis C Meds?
Help! Diving Gives Me Gas
My Ulcer Has Flared Up, Diving?

Hematology Questions
Dive After Donating Blood?
Can I Dive With Anemia?
Can I Dive With Leukemia?

Heart and Vascular Problems
Coronary Bypass Surgery?
Congenital Heart Condition?
Hypertension and diving?
Hypertension Medication
Can I Dive With a Pacemaker?
Thrombosis in finger
Can I Dive with DVT?

Hyperbaric Oxygenation
Unnecessary Chamber Treatment Harmful?

Marine Hazards
What Can I Do About a Jellyfish Sting?
Stings and things
Fire Coral Burn: Long-Term Effects?

Older Divers
Should Older Divers Restrict Their Depths

Pulmonary Problems
Diving With a Chest Cold—Bad News
Causes of a Wet Cough After Diving?
History of Lung Collapses—Diving?
Risks of Diving in Shallow Water?

Sea Sickness
Non-Drowsy Seasickness Medication?
End-of-the-Dive Nausea
Land Sickness? Mal de debarguement? Sopite Syndrome?
I Throw Up Every Time I Dive!

Spinal Cord Injury, Diving?
Dive with a Spinal Cord Injury?

Surgery, Diving?
Back Surgery
Return to Diving, Cartilage Repair
Return to diving, hysterectomy?
Can I Dive After a Vasectomy?

Teen Divers
Do Teens Get DCS More Frequently?
Keeping Kids Warm in Cold Water

Travel Problems
How Do I Keep Bugs From Bugging Me?

Women and Diving
Is It Safe to Dive While Pregnant?
Breast feeding and diving?


Asthma and Diving
I have asthma, and use a bronchodilator before diving. I experience exercise-induced asthma about once every two years, if that, and have had no problems in 40 dives. I lied to get certified, but now I wonder: How much danger am I in?

via email
Telluride, Colo.

When it was suggested that the dive community reconsider its stance on asthma and diving at Divers Alert Network's 26th diving accident and hyperbaric medicine course in May 1995, a hot debate ensued. Asthmatics have bronchial airway obstruction, some more than others. If you remember your diving physics when you were certified, you know that Boyle's law is operative; as the depth and pressure change the volume of an air-filled space has to change (it gets smaller as you descend, larger as you ascend). While breathing compressed air, an asthmatic with obstructed airways can suffer pulmonary barotrauma or a burst lung on ascent. This can lead to arterial gas embolism with devastating brain and heart damage, possibly death (see: www.scuba-doc.com/asthma.htm).

The recommendations that you read on my web page come from the Undersea and Hyperbaric Medical Society's workshop on asthma. I believe that they are conservative and for safety's sake, should be used.

Larry Martin, M.D., offers the following advisory: "A history of bronchial asthma is disqualifying if there have been any attacks within two years, if medication is needed for control, or if bronchospasm has ever been associated with exertion or inhalation of cold air."

It's always a mistake to omit information from your certifying agency and your dive instructor. These rules and guidelines are placed there for your protection (and the agency's). It doesn't mean that they are fixed in cement and cannot be altered if it can be shown that you are not in any danger. It would seem that with 40 dives that you have pretty much found out that it was OK for you to dive safely (given no out-of-air situations). I recommend that you get your lungs checked out carefully before resumption of diving—mainly to rule out terminal airway disease. Possibly a spiral CT scan or a methacholine provocative test would be beneficial in determining any obstructive manifestations.

What does all of this mean to asthmatics who dive, or want to start? Hopefully, the changing perception of asthma and diving will encourage more asthmatics to seek appropriate medical clearance for diving from a doctor with experience in dive medicine. This should result in the screening out of those asthmatics who should not dive under any circumstances, while allowing proper instruction and education of the rest.

Will Asthma Prevent Me from Becoming a Divemaster?
I am going to enroll in a divemaster course, but I have asthma. Could this be a problem?

via e-mail

You shouldn't have any problems tackling divemaster-level training if you have reached the rescue level without asthma problems. However, there may be restrictions imposed by your certifying agency. Historically, asthma has been an absolute contraindication to diving. Diving physicians have felt that the risk for developing arterial gas embolisms is high and that asthmatics should not be permitted to dive.

However, the Undersea and Hyperbaric Medical Society decided that asthma should no longer be considered an absolute contraindication to diving. Rather, divers must be made aware of the risk factors. The following recommendations were made:

    * Exercise- or cold-induced asthmatics should not dive.
    * Asthmatics requiring chronic medications (a bronchodilator within 48 hours of the dive) should not dive.
    * Mild to moderate asthmatics with normal screening spirometry can be considered candidates for diving.
* If an asthmatic has an attack, screening spirometry should be done, and the individual should not dive until his airway function returns to normal.

On the other hand, as in your case, many asthmatics can dive safely. It would seem that some of the old safety concerns have been overstated, and if your physician feels that you can dive, you will probably get along just fine. Based on the latest medical data, the YMCA protocols for asthmatics seem to be the most reasonable (www.ymcascuba.org/ymcascub/asthmatc.html). It isn't wise to dive if you can't meet these standards.

Bad Air Problems
"Bad" Air and Illness
Is it possible to get a bacterial respiratory infection from the air in a "bad" scuba tank?

via email

Depending upon what you mean by "bad" air, the answer is you probably won't get bacterial respiratory infections. Bad air is thought of as having been contaminated by hydrocarbons from a bad filter, or carbon monoxide from a faulty motor. Even "bad" air is pressurized and it is improbable that it would contain bacterial pathogens. It would be more likely that such an infection would be contracted from a focus of infection in your own upper respiratory passages—such as a nasal, sinus or throat infection.

This having been said, however, respiratory infections of various types can be contracted from poorly cleansed and decontaminated gear. Bacterial, fungal and possibly some viral infections can be transmitted from tubing, regulators and mouthpieces.

For more information, go to:

  Can I Use My Asthma Inhalator Before I Dive?

       Is it better to use an asthma inhalator before diving or not use it at all? I read that asthma
       sprays can cause air bubbles to go from veins to the arteries and could cause embolisms.

                                                                via e-mail

  Asthma sprays do not cause air to move from the veins into the arterial circulation. And, in fact, sprays
  would be beneficial in opening up any blockage of the airways and in the process would decrease your
  chances of having pulmonary barotrauma and gas embolism (air into the arterial circulation).

Bone and Joint
Can I Dive After Knee Replacement?

       Q: My doctor says I need total knee replacement. How will this affect my diving after I've
       undergone rehab?

                                                                      via e-mail

       A: You should be able to return to diving after complete rehabilitation from your joint replacement.
       This would require a release from your surgeon for complete weight-bearing and physical rehab of
       the muscles with good joint motion.

       The joint replacement would not be affected by pressure, depth or gases since it is solid and
       contains no air spaces. Whether or not the scarring and surgical changes would tend to be a site for
       nitrogen accumulation due to altered blood supply is debatable. Other good advice would be to
       remove your gear in the water and ask for help on climbing into the boat. Conservative diving would
       also seem appropriate.

       For more information, go to www.scuba-doc.com/bone.htm

Can I Dive After a Leg Strain?

  I recently strained my leg. I'm supposed to go diving in a couple of days. Should I go?

                                                                     via e-mail

  Leg strains vary in severity and often are associated with blood clots. Some experts believe that there is
  an increased risk of bubble formation in regions of tissue where there has been some disruption of blood
  supply. Others say that leg strains generally don't impose any restrictions on diving. A severe strain could
  sideline you for several months if there are any blood clots. Check with your physician to make sure your
  strain is a fairly mild one.

  There are a couple of other factors to consider:

       Heavy scuba gear places significant strain on a diver's legs. Getting back into the boat might be a
       problem. Ask the divemaster if you can remove your gear in the water and hand it to a crew
       There is loss of muscle strength and sometimes actual muscle atrophy with a strain, which can
       affect your mobility in the water. Make sure you can fin easily in a pool before going diving. 

Does Scoliosis Affect My Ability to Dive?

       What can you tell me about scoliosis and how it may affect diving?

                                                                via e-mail

  Probably the main concern with diving with scoliosis is the possibility of decreased pulmonary function.
  Scoliosis varies considerably in the extent of the curvature. Some cases are so severe that the chest
  cavity is distorted and the affected person can have abnormal lung function. This would need to be
  assessed carefully to be sure that you don't have any airway obstruction that could possibly lead to
  barotrauma or a "burst lung."

  Another concern would be possible injury to the spine from lifting heavy weights and tanks. Proper gear
  fit, degree of physical capacity and cardiac reserve (the ability of the heart to handle stressful situations)
  might also play a part in your decision to dive.

  You will likely have more difficulty with gearing up, entries and exits, but this difficulty disappears in the
  relatively gravity-free environment of the sea. The advice of your personal physician should be sought
  with these factors in mind. 

  Can a Fracture Preclude Diving?

       Two years ago, my 20-year-old son broke his elbow in a skiing accident. He had surgery,
       and a small metal bar and screws were used to repair the broken bone. The bone has
       healed and he has no problems with his arm. The metal appliances are still in place.

       He is now interested in pursuing a career in commercial diving and has been asked to
       provide an X-ray of his arm before acceptance into the training facility. Could there be a
       problem with this injury and his choice of career?

                                                                via e-mail

  Whether the site of a fracture is a starting point for bubble formation because of changes in blood flow
  has been the subject of medical debate. There are no consistent studies that show that this assertion is
  valid. There is no good evidence that surgery, fractures or other injury increases the incidence of DCS in
  the injured area. Your son's elbow, even with a metal plate and screws, should not be affected
  disproportionately by the diving environment.

  The agency may be requiring an X-ray to have a baseline for comparison later, should the need arise.
  They may be using some guidelines that they have set up for the protection of the diver (and the agency

  If his fracture has completely healed to the satisfaction of his doctor and he has rehabilitated his elbow
  adequately, your son should be able to dive without difficulty.

Decompression Sickness
What To Do When You Think You Have DCS
Use Oxygen

If you suspect any type of decompression illness, start breathing 100 percent oxygen as soon as possible. Oxygen kits are standard equipment on every reputable dive boat in operation today. Pure oxygen is first aid for any suspected decompression illness because it increases the rate of nitrogen elimination and decreases the size of offending nitrogen bubbles—buying you precious time until you can get medical help.

Call DAN

If you're not sure you have DCS, call DAN's nonemergency number (919-684-2948) to get expert assistance in deciphering your symptoms. DAN has doctors on call 24 hours a day who can help answer questions, as well as ask a few of their own, and arrive at some sort of decision about your complaints.

Did Decompression Sickness Cause My Exhaustion?
On a recent dive trip, I made a dive to 40 feet for 30 minutes, and went to the same depth for the same amount of time on my second dive later that day. The next day I went snorkeling and made a free dive to 20 or 25 feet and forgot to exhale on my way up. I have been feeling tired lately—not extremely tired, but more than normal for me. I also have ringing in my ears, though I always have that. None of my joints ache. Am I overly worried? Could I just be worn out?

via e-mail

Fatigue should be considered when evaluating diving accidents. It is a symptom of decompression illness and often is the only complaint a diver has. Usually, when a diver receives recompression treatment for limb pain, the underlying fatigue disappears along with the pain.

Exhaustion is also a prominent symptom of many other illnesses. Given the dive profile that you describe, your fatigue is most likely not due to decompression sickness. If you continue to have problems, request an exam by a chamber physician and obtain treatment in a chamber. The fatigue might respond to the treatment.

Was My Son's Elbow Pain Caused by DCS?
Shortly after surfacing from an 86-foot dive, my 12-year-old son complained of moderate to severe pain in his elbow. Our computers were one dot in the yellow and our ascents and safety stops were by the book. I experienced no DCS symptoms. After the required surface interval, we made a second dive to 56 feet, even though my son's elbow still hurt.

When we returned to the boat, my son's elbow pain had stopped and didn't return. Is it possible he was slightly bent on his first dive, and that he "decompressed" on the second dive? Also, is there anything about a growing child's physiology that would predispose him to DCS?

via e-mail

It is entirely possible that your child had bubbles in his elbow, particularly if there was no trauma or previous history of arthritis. Joint pain from DCS would improve with recompression but would most likely have returned and worsened after the ascent from the second dive. This is not something you can prove, although an MRI of the elbow might be good to have in case of further difficulty.

There are issues to consider with children diving, such as diving's potential effects on lung, bone and other developing tissue. Children divers should stick to dive profiles that minimize their DCS risk to eliminate possible injury to growing tissues, such as the growth plates of bones. There are no studies that indicate that these growth plates (epiphyseal plates) are a particular problem—just suspicion that an area of increased vascularity might be more susceptible to bubbles. Since the damage that can be done to bone is directly proportional to the length of time at depth, time and depth should be restricted in the growing teenager. A teenager's ascent rates and safety stops should be carefully monitored.

Also of concern is patent foramen ovale, which can allow venous bubbles in the right side of the circulation to cross over into the arterial side and cause clinical bends or arterial gas embolism. It is known that the rate of closure of a patent foramen ovale in the heart is highly variable and in some children, it will not have closed by age 7. This is something that your pediatrician can check.

Can DCS Cause Strokes?
A friend of mine suffered some strokes a couple of years after one doctor said she might have decompression sickness. At that time, she was an airline attendant and flew after a dive, supposedly with enough time in between the dive and flying to be safe. A few days after the flight, she experienced some symptoms of DCS. Her physician said she might have DCS, but that it was too late for recompression therapy. She has since had the strokes and had many tests. Some doctors say she has a connective tissue disorder, and others say it is because she got bent, and that she could die suddenly. The tests did find damage to her brain. If she had DCS, could it have caused the air bubbles to constrict blood vessels in the brain, leading to her strokes?

via e-mail

It's improbable that your friend's strokes are related to decompression sickness. The possible relationship to a patent foramen ovale—a condition where blood can flow from the right chamber to the left across the heart without passing through the natural filter of the lungs—might be the reason, but in this case it's impossible to prove. In a diver with a PFO, the bubbles could bypass the lungs and flow directly to the brain, where they could cause what are essentially mini-strokes. Over time, enough of these small strokes could cause neurological or cognitive deficits. If your friend has not been evaluated for an abnormal right-to-left shunt in the heart, then she should consider this. For more information on PFO, go to www.scuba-doc.com/pfo.htm.

Bubbles from a decompression accident don't linger, but are absorbed gradually. Recompression of the bubbles is done because this improves the outcome markedly—even as much as several days later. However, the damage that these bubbles cause with subsequent scarring can lead to residual neurological changes, varying with the part of the brain left scarred. It's impossible to say whether your friend's previous decompression accident or the strokes have caused her difficulties.

DCS after joint surgery?
Is There Increased Risk of DCS After Knee Surgery?
I am 37 years old and had two knee surgeries in 1995. Am I more susceptible to DCS in that area?

via e-mail

There is no evidence that surgery, fractures or other injury increases the incidence of decompression in an area. Risks of DCS are often predicated on unproven assumptions of bubble accumulation at sites of altered blood flow, either increased or decreased.

You will likely have more difficulty than usual with gearing up and doing sea entries and exits, but this disappears after you are in the relatively gravity-free environment of the sea.

If your surgeries have completely healed to the satisfaction of your surgeon—then you should be able to dive without difficulty.

Can a Person Recover from Paralysis Caused by DCS?
A friend of mine got decompression sickness. One week after getting bent, after having three recompression sessions, six hours each, he still has no use of his legs. He is paralyzed from the sternum down. Is there any way he will be able to walk again?

via e-mail

A friend of mine got the bends while diving. He is now in a wheelchair. Is this reversible?

via e-mail

The answer in both cases is most likely no. The bends is what divers call decompression sickness. In its worst form it can cause permanent neurological damage to the spinal cord and brain. In the U.S. alone, Divers Alert Network (DAN) reported 590 cases in 1995. Of course, there are many millions of dives made each year by the estimated millions of divers in the U.S.

The condition is prevented by carefully following the rules of diving at all times and is treated by early recompression in a hyperbaric chamber. Treatment is generally continued until there is diminishing or no response to the treatment. Response is highly variable and not readily predictable. Oxygen administration after recompression treatment is helpful in reducing recurrences of DCS. Rehabilitation programs often enable paralyzed patients to return to some level of function. The attending physician should be able to tell you more about your friends' outcomes.

Did DCS Cause My Chronic Back Pain?

In the last few years, my back has been "going out," landing me in bed for about two days. The last two episodes occurred on a dive boat, just after a dive. Both times, I felt a "pop" in my lower back. I am 39 and in good health. I work out three to five days a week, riding a stationary bike and lifting weights.

An orthopedic specialist says I have some arthritis in my right hip joint. He is concerned that the chronic pain is because of a diving-related injury. He said I might have a form of bends, and each subsequent dive is aggravating the injury further. I have an MRI scheduled in a month to see if bubbles are concentrated in my lower back area. What do you think?

via e-mail

I think this is a mechanical back problem unrelated to diving. You need to be sure that the arthritis of the right hip is not dysbaric osteonecrosis. A thorough examination by a neurologist could settle this once and for all.
Since you describe your back "going out" with a pop, I don't think your back problem has been caused by a decompression accident, especially since you don't mention any neurological symptoms. I suspect chronic lumbosacral strain or arthritis. The orthopedist is correct in noting that your hip problem could be due to diving since there's the possibility of dysbaric osteonecrosis in divers who have made poorly controlled deep dives. This would show up on an X-ray, and should be relatively easy to diagnose.

Bubbles wouldn't show up in diagnostic testing as they don't hang around very long and are absorbed by the body. Their "footprints" remain as scars from the resulting tissue damage and as inflammation, which occurs with a decompression accident. Subsequent diving does seem to concentrate new bubbles in or around the areas of previous damage. The MRI might show damaged areas, but you would surely have had some neurological indication of this.

Outcome of DCS Joint Pain
Will the joint pain resulting from untreated decompression sickness disappear after time or will it just get worse?

                                                                via e-mail

  Joint pain that is due to a decompression accident is caused by several things:

       the pressure caused by the actual presence of bubbles in the tissues around the joint

       the production of chemicals called kinins that cause an inflammatory response similar to arthritis

       tissue that is damaged when clotting and other protective systems are triggered, resulting in pain,
       increased blood flow and swelling.

  Compression, such as a blood pressure cuff or a tightly wound Ace bandage, usually causes an
  immediate decrease in pain. However, if left untreated, the pain has a greater chance of being caused by
  the effect of kinins, swelling and loss of blood flow. In this case, the pain might last for an indeterminate
  period—sometimes for weeks or longer. This untreated damage might also tend to make the diver more
  susceptible to subsequent episodes of decompression illness.

  Bubbles have been found in divers even after what was thought to have been successful treatment of
  DCS. Consequently, it would be wise to recompress every case of DCS using oxygen alternated with air
  (the oxygen replaces the nitrogen and is metabolized rapidly, reducing bubble size even more). 

Return to Diving after DCS?
Can I Dive After Getting Bent?
I read an article that said because decompression illness can cause subtle but lasting changes in the circulatory system, doctors recommend that someone who has suffered the bends never dive again. Is this true?

via e-mail

Not entirely. There are many different forms of decompression illness. Some leave few indications of its presence; but some leave significant scarring, particularly in the central nervous system.

Many physicians believe a person should not return to diving if he or she has experienced severe neurological spinal or cerebral decompression illness (Type II) with residual neurological symptoms. One of the reasons for this is the known increased risk of recurrent decompression illness in the area of scarring from the previous sites of the bubbles.

The recommendations for diving after a bout with the bends:

# Type I DCS—If uncomplicated and produced by exceeding dive profiles or ascent rates, a diver may return to diving in four weeks.

# Type I DCS, unexpected—Should return to diving only after ruling out diseases and factors that might increase susceptibility. Change of diving to a more conservative pattern.

# Complicated Type I; neurological and other Type II DCS—Return to diving in a limited manner (no decompression dives, bottom times halved, maximum depth 50 feet and surface intervals of six hours) one month after identifying all causes and undergoing full neuropsychological assessment.

Missed Safety Stop = Near Miss?

  The sixth Caribbean dive of our week started easily, but when I ran low on air, my fiancée and I
  ascended from 40 feet to our safety stop. Although we ascended slowly, we missed 15 feet. After
  hovering around 10 feet for a minute, we surfaced. The water was choppy, a strong current pulled us
  around, the warm air had cooled and it was raining. We used a towel to keep us somewhat warm on the
  chilly 10-minute boat ride back. After rinsing our gear, we did a brisk walk/jog up 200 steps to our
  hillside bungalow to shower and warm up. My fiancée mentioned that she had cotton mouth and was
  pretty thirsty. Shortly after she got out of the shower her fingers began to ache and were tingly. I ran
  back down to the dive shop and called DAN. They said my fiancée had felt the tingling because she took
  a hot shower when she was cold—more of a circulation issue than DCS. A couple hours later, her hands
  felt fine and there has not been anything wrong since then. Should she get checked out by a dive
  physician anyway?

                                                                     via e-mail

  I don't think so. Coming up cold and tired is typical after a dive. Even though her ascent might have been
  rapid and irregular due to the wave action and surge, increasing the risk of both DCS and pulmonary
  barotrauma (and possible gas embolism), I think DAN made the right call. Both the run up the hill and
  the hot shower can possibly release bubbles in the tissues. However, your fiancée's clinical picture does
  not indicate DCS.

Can DCS Cause Joint Aches Years Later?
My 50-year-old husband suffered a hit of decompression sickness 17 years ago. He was in a recompression chamber for at least eight hours. At the time, he only dived about once or twice a year. He has not dived since then. In the last few years, he has had a lot of joint aches. His physician told him the joint pain could be from the decompression accident. Can a person experience pain this long after a dive accident?

via e-mail

If your husband has a condition called aseptic necrosis of the bone, which causes a collapse of the joint surface and results in joint pain, his diving accident could have caused it, even many years after the injury. This condition is relatively easy to diagnose once X-rays have been taken. When the surface of the joint (generally the shoulders, hips and knees) is affected by the necrosis, physicians usually recommend joint replacement.

Do I Have the Knee Bends?

  After a Caribbean dive trip, a lump and a bruise appeared on the back of my knee. We made 17 dives in
  a week, including two morning dives on the day before the departure. A lump of one-inch diameter and
  one-half-inch high appeared with sharp pain on the back of my knee when I arrived home. The lump hurt
  when touched, and appeared to be filled with blood (dark blue). The next morning, a bruise appeared
  around the lump; the bruise is now about five inches in diameter. The lump still hurts when I touch it, but
  is no longer blue. I called Divers Alert Network and was advised that I don't have to worry about DCS. I
  wonder if I have gas trapped in the tissue at the back of my knee. What do you think?
 via email, New York, N.Y.

  First, we would agree with DAN that this is not DCS; nor is there the possibility of gas being trapped in the
  tissues behind the knee. There are no air-containing structures in that area, and any nitrogen in the body
  would have dissipated by the time you arrived home.

  The most likely cause of the lump would be the rupture of a small superficial vein in the back of the knee
  caused by pressure from the airplane seat over a prolonged period of time. The small blood clot would
  then slowly spread into the subcutaneous fat, causing the bruise.
  This would have been more likely to occur if you have been taking aspirin or NSAIDS for some arthritic

  I don't think this is a diving-related injury. Your doctor might want to run a few studies on your
  blood-clotting parameters just to be on the safe side.

Dehydration and Diving?
What Caused My Dry Mouth?

After two days of diving recently, I developed an irritated throat that progressed to a rather nasty condition—dry and quite sore—for another six days after returning home. Because I am scheduled to take a weeklong live-aboard trip soon, I need some advice on how to prevent dry mouth and throat irritation from repeated diving.

- via email  Allen, Texas

It may be that your problem was a viral pharyngitis or some other infectious condition. It also could have been caused by not swallowing while under water. Saliva can help prevent the dry mouth caused by the dry air in your scuba cylinder. Your saliva glands can be stimulated by using the SeaCure mouthpiece (www.seacure1.com) or placing minty toothpaste on your mouthpiece.

If your dry mouth was caused by dehydration, however, you need to examine your habits before you dive to prevent dehydration on your next dive. The air in your scuba tank is as dry as the Sahara, the moisture having been removed from it in order to protect the inside of your tank and regulator from corrosion. Each incoming breath of dry air picks up moisture from your throat and lungs and carries it out when you exhale, so every breath represents a loss of water.

How much? Not as much as you'd guess from the cotton-mouth feeling that results. On a four-tank day you'll breathe about 260 cubic feet of dry air (assuming 80-cubic-foot tanks—actually 77.4—and a minimum pressure of 500 psi). The maximum amount of water that much air could have contained (at 100 percent humidity, 86F) is about one cup. In fact, you probably lose less. Research reported in the journal Respiration Physiology suggests that most of this water loss occurs in the first 15 minutes when your upper respiratory tract dries out. Regulators that trap moisture in the second stage to moisten incoming air lessen, but probably don't entirely prevent, the drying effect of breathing tank air.
Hydration Hazard: Caffeine

Yes, a cup of coffee is mostly water. But the caffeine is a diuretic, sucking water out of your tissues and sending it to your bladder. As a result, drinking 12 ounces of coffee results in 12, 15, 20 or more ounces of urine and a net loss in your hydration score.

Caffeine is sneaky. It's in more foods and beverages than you might think. Popular soft drinks have a range of caffeine concentrations between 36 and 48 milligrams, with Jolt Cola the chart topper at 72. Coffee has the highest concentration, up to 180 milligrams per five-ounce cup. Tea can have as much as 50 milligrams per cup, and both tea and chocolate are loaded with substances called xanthines, which are also diuretic.

Suck It Up: SCUDA

Divers with a severe dry mouth problem may want to consider another equipment solution, the SCUDA (self-contained underwater drinking apparatus) made by SCUDA Marketing. The SCUDA is a wine-skin type device that holds water and allows you to drink through your regulator—squeeze the bag and water squirts into your mouth. The SCUDA doesn't affect the breathing characteristics of a regulator, but because it attaches to the primary hose, it does affect regulator ergonomics. There's also the possibility that you'll gag on water squirted inadvertently or too forcefully into your mouth. The SCUDA is not a great idea for most divers, but those with serious dryness of the mouth may want to try it.

What Makes Me Want to Pee While Diving?

  When diving, I suddenly get the urge to pee, even though I voided only minutes before. Why do I need
  to pee so soon?

                                                                     via e-mail

  This physiological phenomenon is known as immersion diuresis, a fancy term for your body's response to
  feeling under pressure. Blood is shifted to your body's core, and the hypothalamus gland thinks this
  means your total fluid volume is too high and instructs your kidneys to make urine. What can you do to
  avoid immersion diuresis?

       Avoid diuretics like caffeine before you dive.
       Intentionally dehydrating yourself might seem like a good idea, but dehydration increases fatigue
       and predisposes you to decompression sickness.
       Try to stay warm. A side effect of your body's response to cold is the production of urine. Wearing
       a hooded vest under your wetsuit may save you from having to empty your bladder when you least
       want to. On the boat, stay out of the wind, bundle up and wear a hat.
       Be healthy, sober and rested. A variety of over-the-counter and prescription drugs can interfere
       with your body's heat conservation mechanisms, typically by preventing the constriction of blood
       vessels near the skin. Antihistamines are particularly suspect. Alcohol is worse.
       Although adipose tissue insulates well, allowing fat people to tolerate cold water immersion longer
       than lean people, it's better to be physically fit.

Deep Water Blackout

Why Did My Buddy Black Out?
My buddy and I (both very experienced divers) planned a deep canyon dive to 60 meters. At 53 meters, my buddy signaled that he had nitrogen narcosis and was going to ascend. He was ascending very fast, so I stopped him by grabbing his fins. At 30 meters, I grabbed his BC strap and signaled, "Are you OK?" but got no response. He was breathing and had some water in his mask. When we reached 12 meters, he regained consciousness. We continued to the surface, skipping the required safety stop. The dive lasted 12 minutes. We stayed one minute at 53 meters with no deco violation. My dive computer showed that I violated the ascent rate three times. At the surface, my buddy was breathing normally. As soon as we were on the boat I administered oxygen. After the dive ended, he told me that he had felt tingling in his body, that it was very hard to breathe and that he blacked out. What happened? Did I do the right thing?

via e-mail

This is probably "deep water blackout" given a normally functioning regulator. This condition has been described by "Diving Medicine Online" consultant Dr. David Elliott as a combination of low partial pressure of oxygen, high partial pressure of nitrogen and high partial pressure of carbon dioxide. Your buddy's improvement on ascent is revealing. Your quick action probably saved your friend from arterial gas embolism and possible death. I'm delighted to hear that you had oxygen on board, as this was the treatment of choice. Any possible benefit from recompression is a moot point now, of course.

The second stage of his regulator could have malfunctioned and this might have started the whole landslide of hypoxia and hypercarbia and the depth caused the high nitrogen. I have seen one similar case in an experienced diver at 90 feet, which resulted in the rescue and resuscitation from gas embolism due to a "lack of air at depth" and near drowning. His buddy was not as attentive as you, however, and pulmonary barotrauma occurred. He had plenty of air in his tank on surfacing.

Dental Problems
Can I Dive After a Root Canal?

  I heard a strange rumor that you should not dive for two weeks after getting a root canal—that on
  ascent, your tooth could explode or pop off. Is this true?

                                                                     via e-mail

  Your concern is not a rumor. If there is any air left in the end of the root canal, this air could implode on
  descent or do just the opposite on ascent. The air is subject to all the forces of Boyle's Law, just as any
  other air-containing structure in the body (sinuses, ears, lungs, intestine).

  If you are about to have a root canal or if you've just had one, follow these recommendations:

       All canals must be filled to the top to avoid accumulation of compressed gases and pain,
       especially on ascent.
       Try to finish the root canal in one visit. Multiple visits require the dentist to place a temporary
       filling over a cotton pellet in your mouth.
       If multiple visits are required, and cotton must be put into the tooth, do not dive. Diving must wait
       until all air spaces or potential air spaces are closed. Diving with an air space can lead to the
       implosion of the tooth.
       Once the root canal is finished, the dentist will fill the space with temporary cement and no air
       spaces. Following a root canal, a cap (crown) is placed on the tooth.
       Wait to dive for a period of two weeks or until there is evidence of complete healing without air

Diving with Dental Implants
I am a 64-year-old female who dives every weekend. I have had four dental implants this week. How long do I have to wait before diving again?

via e-mail

The only concern about diving with dental implants would be whether you can clamp down on the regulator's mouthpiece without difficulty and without damaging the implants. If the procedure your dentist performed has been successful, and the implants can withstand normal biting pressure, you should be able to dive again. Your dentist can make this determination after he or she has given you the OK to resume normal eating and chewing.

Help! My Reg Makes Me Gag
As a new diver (12 dives), I have a problem with a strong gag reflex when the regulator is in my mouth. Any ideas about a solution?

via e-mail

You could try mirror biofeedback. Using a mirror, start with a snorkel, inhale to the count of 4 and exhale to the count of 6 (relax as you exhale). Watch your face relax in the mirror. If you see your face, jaw, eyes, neck and shoulders relax, then you are doing it right. Then try the same exercise with tongue depressors in your mouth. Finally, try it with your reg mouthpiece.

It may be that the mouthpiece of your reg needs to be trimmed. Remove any excess silicone that extends back to your back teeth and trim the excess that hits the roof of your mouth. Another option is to swim laps in the pool with a snorkel until the gag reflex goes away. If you only experience it with a regulator mouthpiece and not with a snorkel (having a virtually identical mouthpiece), it may be that the gagging is anxiety-related, and not anatomical or physiological in nature.

Some dentists sprinkle sugar or salt on the tongue or palate before making dental impressions to inhibit the gag reflex. A topical anesthetic works well—especially Dyclone, which is longer-acting.

Finally, if these suggestions don't work for you, consider getting a full face mask.

  Can Diving Cause Dental Problems?

       I dived for the first time this past winter (seven dives in two-and-a-half days) and since
       then I've needed a lot of dental work done. Do you think there's any connection?

                                                                via e-mail

  Your problem could definitely be related to diving. First, you may have already had dental work that was
  either loose or in need of repair. If there were any air pockets between your fillings and the tooth surface,
  then diving would definitely have caused some changes. The trapped air would change in volume as you
  descended and ascended in the water column, further loosening your repair work.

  Second, you could be using a poorly fitting regulator mouthpiece, causing the repair work to loosen. By
  the same token, you might have clamped your mouthpiece too tightly, causing some tooth damage.

  For more information: www.scuba-doc.com/dentprbs.html.

Dermatological Problems

  Fire Coral Scars

  I came into contact with what I believe was fire coral in the British Virgin Islands about five weeks ago.
  Thinking it wouldn't be much of a problem, I didn't see a doctor until the rash worsened several days
  later, after I returned home. I have been using a prescription cream, Cormax, for four weeks and the
  rash is about 80 percent better. However, the entire area is still visibly darker, almost like a burn scar,
  with a couple bumps. Is there something else I should do? Will this scar completely heal?

                                                                     via e-mail

  Coral scrapes do have a tendency to become both chronically irritated and infected. Occasionally, coral
  scrapes and cuts will have trouble healing and break out in a chronic dermatitis or a weeping wound. This
  is thought to be due to the persistent toxic or allergic effects of the small bits of coral (often microscopic)
  that are embedded in the wound at the time of the injury.

  Initially, wounds should be flushed with large quantities of vinegar or whatever sterile fluid you have
  available. You should get a tetanus shot and treat the wound with a combination of triple
  antibiotic/steroid cream until healing occurs.

  If the wound does not appear to be healing after 24 to 36 hours, check with your doctor to see if you
  need to undergo a procedure called debridement (removal of foreign bodies). Hyperpigmentation (dark
  color changes) is more difficult to manage and requires the assistance of a good dermatologist.

  Cormax is the trade name for clobetasol, a topical steroid cream. It reduces or inhibits the actions of
  chemicals in the body that cause inflammation, redness and swelling. It is used to treat the inflammation
  caused by a number of conditions such as allergic reactions, eczema and psoriasis and would possibly be
  indicated for the coral dermatitis that you seem to have. People have varying reactions to the dermatitis
  and the medication. Most dermatologists are highly trained to manage conditions of this nature and a
  visit to one might be wise in the long run.

Seabather's Eruption

  What is seabather's eruption, and when should I worry about it?
  Hamilton, Ontario, Canada

  The skin condition known as seabather's eruption, also called swimmer's itch, appears as a rash of raised
  red bumps, often concentrated on areas of the skin covered by a swimsuit or wetsuit. Symptoms develop
  between two and 24 hours after exposure to the organisms that cause the condition and usually resolve
  within a week. Symptoms can also include nausea, vomiting, diarrhea, headache and muscle spasms.

  Seabather's eruption can be caused by various organisms that produce larvae with nematocysts, including
  jellyfish, corals, sea anemones, hydroids and Portuguese man-o-wars. Outbreaks in the Caribbean and
  southern Florida are believed to be caused by the larval form of the thimble jellyfish.

  Outbreaks of seabather's eruption occur intermittently between March and August in the Caribbean and
  southern Florida, but they appear to peak from early April through early July. There are many days when
  no infestations occur. Beachgoers should listen to local beach reports and read beach messages posted
  daily in affected areas.

  In other tropical waters, seabather's eruption appears to be associated with periodic anemone larvae
  blooms, and can occur throughout the year. See our chart for thumbnail sketches of the animals that
  sting under water, and what to do about the associated injuries. 

Diabetes and Diving
Question: Can I dive with diabetes?

Answer: The short answer is—maybe.

Until the middle of the 1990s, the official medical advice was that diving with diabetes was too risky. Thanks to research by Steve Prosterman of the University of the Virgin Islands, the Undersea and Hyperbaric Medical Society, the Divers Alert Network (DAN) and the British Sub-Aqua Club (BSAC), we've learned a lot in the last few years, and today, it's a case-by-case decision based on how well the diabetic controls his condition.

If you're a diabetic who dives or wants to dive, the first step is to consult your personal physician to learn as much about controlling your condition as possible.

Question: How can diabetes affect a diver?

Answer: Diabetics can be at risk from the effects of both the condition and the methods of controlling it.

    * The possibility of seizures and loss of consciousness from hypoglycemia has been the big obstacle to certifying diabetics.
    * Insulin reactions and the resulting rapid onset of low blood sugar levels can impair judgment.
* Diabetics not in control of their condition excrete excess sugar in urine, a process that leads to dehydration and puts the diver at greater risk of DCS.

Question: So who can and can't dive?

Answer: Any diabetic who can't recognize hypoglycemia (low blood sugar), hyperglycemia (high blood sugar), or who is diagnosed with ketoacidosis (acidic condition from breakdown of ketones) or organ disease (kidneys, eyes, heart) must be disqualified. Sorry, the risks are still too great.

The good news: Diabetics who practice excellent self-management, understand the relationship between exercise and diabetes, and are disciplined enough to follow these guidelines are qualified for conservative sport diving without problem.

Are there guidelines for diving with diabetes?

The Guidelines
Before Diving

    * Wear a medical ID stating that you are diabetic and also a diver.
    * Hydration is doubly important to the diabetic diver to prevent decompression illness.
    * Maintain good physical condition and good diving skills.
    * Don't dive if you: Can't recognize when you are having a reaction, don't completely understand your condition or if you have any concurrent illness.
    * Tell the divemaster. He or she must be aware that you're a diabetic and should also be informed of your intended profile.
    * Tell your buddy. The diabetic diver's buddy should be familiar with the diabetic, aware of potential problems and properly trained in responding to them.
* Monitor and stabilize blood glucose. Blood glucose should be monitored before every dive and stabilized at 150 to 180 mg/dl prior to the dive. Steve Prosterman, dive supervisor at the University of the Virgin Islands, recommends a minimum of three blood glucose measurements within one hour prior to diving (e.g., 1 hour, 30 minutes, and five to 10 minutes prior).

"The important thing is to find the direction of the blood glucose. Under no circumstances should a dive be performed if the blood glucose is dropping," Prosterman says. "If it's going down, take carbos to stabilize it. Usually it can be corrected after the second test."

If blood glucose levels are rising, aim for a minimum reading of 120 to 130mg/dl before diving.

* Pack a dive kit. This must include: two separate packs of oral glucose paste or tablets in waterproof containers; an emergency intra-muscular injection of glucagon to rapidly raise dangerously low blood sugar levels (make sure someone in your dive party is capable of administering the injection); and a glucose-measuring kit with instructions.

During the Dive

    * Always carry oral glucose under water. A glucose gel in a plastic container, like InstaGlucose, is recommended. Both the diver and his non-diabetic buddy should carry two tubes each.
    * Communicate with your buddy. The diabetic diver and buddy should have hand signals and an abort plan well established in the event of a reaction under water. Prosterman recommends an "L" sign for low blood sugar. When the sign is given, both divers surface and inflate their BCs. The diabetic immediately ingests carbos before the buddy team returns to the boat or shore.
* Limit your depth to 80 to 90 feet. This will help you avoid nitrogen narcosis, which may be confused with—or mask—an insulin reaction. Under no circumstances should diabetics engage in decompression diving, which limits the diver's ability to surface promptly in case of low blood sugar.

After the Dive

    * Check your glucose level. Correct as necessary. By tracking the drop in blood sugar after dives, diabetics can learn to better control their condition.
* Report any adverse symptoms. Symptoms of low blood sugar can mask decompression illness (DCI) and vice versa. Unless there is a reason to suspect DCI, Prosterman recommends treating for low blood sugar first, which will resolve in 10 to 15 minutes. If symptoms do not resolve with glucose, treat the case as a dive accident by administering 100 percent oxygen and calling for medical help.

Question: So I should come clean with my dive instructor or dive guide about my condition?

Answer: Absolutely.

For years, diabetic divers have hidden their conditions in order to participate. As the dive community begins to recognize the new rules for diabetes, the safest—and most responsible—course of action is full disclosure. It's important that your buddy and divemaster be fully aware of potential reactions and how to respond to them.

What is Diabetes?
Diabetes mellitus, also called "the sugar disease," occurs when the pancreas can't produce enough of the hormone insulin to convert glucose from food into energy. It affects five to seven percent of the population.

There are two main types of diabetes. Type I, also called insulin dependent diabetes, normally affects children or adolescents.

Type II, also called non-insulin dependent diabetes or adult-onset diabetes, accounts for 90 percent of cases and usually occurs in overweight adults.

Treatments for diabetes include daily insulin injections to lower high blood sugar levels, oral medications, regulating the diet, exercise and constant blood glucose monitoring.

Are there diving programs for Diabetics?

There's no better role model for diabetic divers than Stephen Prosterman, diving supervisor at the University of the Virgin Islands. Diagnosed at the age of nine, Prosterman never let his condition get in the way of an active lifestyle. And when he moved to the islands more than 20 years ago, that lifestyle soon included diving.

His love for the sport led him to create the first protocol for responsible diving with diabetes, and this work spurred much of today's ongoing research. It also led to Camp DAVI, an annual summer program for diabetics 17 and older that uses diving and other adventure sports to teach campers how to tightly manage their condition. The program, overseen by Dr. Doren Frederickson of the Kansas University School of Medicine, also advances research into diving with diabetes.

For more information on Camp DAVI, call (340) 693-1399, e-mail Steve Prosterman at sproste@usvi.edu or visit the web site at www.diabetesnet.com/visle.html.

Warning Signs of Diabetes?
Adult-onset diabetes usually occurs in overweight middle-aged people. Sound like anyone you know? See your doctor immediately if any of the following symptoms apply to you:

    * Any family history of diabetes.
    * Frequent urination.
    * Unexplained weight loss.
    * Ravenous appetite.
    * Constant thirst.
    * Constant sleepiness.
    * Blurred vision.
    * Sticky urine.
    * Shakiness after a high-carbohydrate meal.
    * Easy fatigue and nausea.
* A tendency to get fungal and bacterial infections.

According to the National Diabetes Information Clearinghouse, 798,000 new cases of diabetes are discovered each year. Unfortunately, an estimated 5.4 million people remain undiagnosed and are at risk for the long-term damage that can result—including heart disease, stroke, high blood pressure, blindness, kidney disease and nervous system damage.

Drugs and Diving?
Dive Medicine Tips
Want to know if it's OK to dive while taking a drug your physician has prescribed? Follow these steps in considering the relationships between drugs and diving:

    * Go to the "Fitness to Dive" section of "Diving Medicine Online" at www.scuba-doc.com and look up the condition, illness or disease for which the medication is being given and find whether there are any prohibitions against diving with that condition or while taking that medication.
    * Determine whether the drug alters consciousness or causes alteration in decision-making ability.
    * Consider complex relationships between drugs, the individual, other medications, diet and the conditions for which the drugs are taken.
* Consult a physician who is trained in dive medicine. 

Benadryl Sedating?
It is my understanding that Benadryl (diphenhydramine) is considered to be a sedating antihistamine, and is, in fact, sometimes used as a sleep aid. I also recall seeing a caution on a Benadryl box indicating that it "causes marked drowsiness." If this is correct, would Benadryl be contraindicated for divers? You recommend it for divers not once, but twice in the Oct. '99 issue.

via scubadiving.com
message board

Benadryl is an over-the-counter medication that causes some side effects in some people. The fact that it causes drowsiness in some people does not indicate that it would necessarily be dangerous to all divers. Diving per se is not known to increase its effect. It is doubtful that the FDA would turn it loose if there was major danger. After all, there are a lot more drivers than divers.

Every drug or medication has some side effects on some people. One should not dive after taking this or any drug until their response to the drug has been determined.

However, since the mild depressant effects of antihistamines are additive to those of other drugs affecting the central nervous system, patients should be cautioned against drinking alcoholic beverages or taking hypnotics, sedatives, psychotherapeutic agents or other drugs with central nervous system depressant effects during antihistamine therapy.

Diphenhydramine should be used with caution in patients with a history of bronchial asthma, increased intraocular pressure, hyperthyroidism, cardiovascular disease or hypertension, all of which are clear hazards to divers if uncontrolled. Other listed adverse effects of Benadryl include: drowsiness, dizziness, dryness of mouth, nausea and nervousness. Other infrequently reported effects are vertigo, palpitation, blurring of vision, headache, restlessness, insomnia and thickening of bronchial secretions. Allergic reactions, diarrhea, vomiting and excitation may also occur.

ENT Problems

Trouble Clearing
This summer I made two quarry dives to 50 feet. On the second dive, I had trouble clearing my right ear. I went up and tried again, but still no luck. On the third attempt, I felt it clear--well, sort of. Instead of the usual pop, I heard a series of squeaks from my right ear. Could it have been caused by my mask and hood covering the area? I always take Sudafed an hour prior to diving as a doctor recommended many years ago after a sinus problem. On the way home, I had mild discomfort in that ear. That night I took two aspirin, and I was fine the next day. Do you think I damaged my eustachian tubes? Do they heal? Should I see a doctor?

- via email, New York, N.Y.

It is possible that you have some type of blockage of your nasal lining near the opening of your eustachian tubes, possibly polyps, bony growths, nasal septal deviation or allergic rhinitis. If it comes and goes, the most likely cause would be that the mucosa is swelling at various intervals, possibly as the result of allergy, irritations from fumes or from congestion from any of a thousand other sources. This may have caused some middle ear barotrauma, with swelling and serum accumulation in your middle ear.

If a good ear, nose and throat exam fails to expose any pathology in the back of your nose, then you might need to check into your diving technique. Descending feet-first on the anchor line or a down line can help you rise slowly just a foot or two to take the pressure off and help you clear easily.

Try a Different Clearing Technique

You might also want to try using a different technique for clearing your ears. The Valsalva maneuver--pinching your nostrils and blowing through your nose--is the most commonly used technique, but might not be the best one for you. One problem with the Valsalva maneuver is that it doesn't activate muscles that open the eustachian tubes, so it may not work if the tubes are already locked by a pressure differential (see illustrations). It's also easy to blow hard enough to damage something. Instead of using the Valsalva next time, try one of these:

    * The Toynbee Maneuver. With your nostrils pinched or blocked against your mask skirt, swallow. Swallowing pulls open your eustachian tubes while the movement of your tongue, with your nose closed, compresses air against them.
    * The Lowry Technique. A combination of Valsalva and Toynbee: While closing your nostrils, blow and swallow at the same time.
    * The Edmonds Technique. While tensing the soft palate (the soft tissue at the back of the roof of your mouth) and throat muscles and pushing the jaw forward and down, do a Valsalva maneuver.
    * The Frenzel Maneuver. Close your nostrils, and close the back of your throat as if straining to lift a weight. Then make the sound of the letter "K." This forces the back of your tongue upward, compressing air against the openings of your eustachian tubes.
    * Voluntary Tubal Opening. Tense the muscles of the soft palate and the throat while pushing your jaw forward and down as if starting to yawn. These muscles pull the eustachian tubes open. This requires a lot of practice, but some divers can learn to control those muscles and hold their tubes open for continuous equalization.

Try Medications

In addition, you can use medications that help reduce the swelling around the opening to the eustachian tubes. Most people use and get good results from oral Sudafed tablets. Afrin nasal spray, for a day or two only, also is helpful, but can cause troublesome rebound congestion. Taking oral Sudafed throughout a dive trip would not be harmful, nor would it cause rebound congestion. The newer antihistamines (Allegra, Claritin and Zyrtec) might be helpful, taken on the advice of your physician. Flonase is also helpful for some people.

For more information on dealing with ear troubles, go to: www.scubadiving.com/training/medicine/earproblems.shtml or www.scuba-doc.com/entprobs.html.

 Why Can't I Equalize One Ear?
My right ear equalizes perfectly, with no problems at all, but my left ear is another story. Everything I've tried—from using an anchor line to slow down my descent to clearing my ears before the dive—has not helped. Is there anything that could be causing this problem?

via e-mail

Unequal clearing usually indicates one of two things: poor technique or some abnormality in the back of the nose causing blockage of the opening to the eustachian tube.

Though you've tried various methods to help clear your ears, read "Pain-Free Equalizing," in case there is a method you haven't tried.

If it's an abnormality that's preventing you from equalizing, there is good news. Lots of these can be corrected easily, including polyps, allergic rhinitis and bony growths around the opening to the eustachian tube. A visit to an ear, nose and throat specialist can determine if you have one of these conditions.

Equalizing with Tiny Tubes
I have small Eustachian tubes and read about ways to help equalize pressure in your magazine. None of the methods worked for me. I was wondering if there is scuba equipment that allows divers with my condition to dive without pain?

via email
Greenville, S.C.

There are no scuba apparatuses or equipment that will perform the function that you wish. There probably are people who are born with congenitally small or narrow Eustachian tubes, but this would definitely be the minority. Most people have a correctable cause for their inability to equalize when diving. You are strongly advised to see a good ear, nose and throat specialist who is diving oriented and find out if you have some problem that can be altered surgically.

Blood in My Mask
I usually have some blood in my mask (it all comes from my nose) after diving. Blowing my nose usually reveals some orange stuff that doesn't seem to help me attract much positive attention from the ladies. I tend to equalize pretty slowly, but the presence of the orange stuff doesn't seem to be dependent on difficulty in descending.

I'm assuming it's a mixture of blood and mucus. Am I going to live? Will I ever play the piano again?

by email

The old "blood in the mask" gambit is guaranteed to scare the diver, get attention from his buddy, attract sharks and other top-of-the-food-chain animals, and turn off the ladies (and anyone else who doesn't like orangish-pink snot). You'll survive, though I don't know if you'll ever play the piano again.

All kidding aside, yours is a frequently asked question (because it happens frequently) and the simple answer is that it is harmless, usually caused by mask squeeze, sinus barotrauma or excessive nose-squeezing with clearing attempts. If you are concerned, it might be wise to go to an ear, nose and throat doctor and be certain that you don't have something that can be corrected—such as septal deviation, chronic rhinitis, polyps or tumors.

For more information, go to:

What Is Causing My Sinus Problems Under Water?

       I apparently have an ongoing sinus infection that is only evident when I dive. I take the
       prescription drug Augmentin with me now when I go on vacation because without it I
       sometimes get pressure in my sinuses when I descend. Both my regular doctor and a
       specialist say that the infection is something that is most likely ongoing and will never be
       completely eradicated, only diminished with antibiotics. It causes me absolutely no
       problems topside. No allergies, no itchy, watery eyes, nothing. It only shows up when I
       dive. What is going on?

                                                                via e-mail

  You probably have something obstructing the outlet of the affected sinus—such as a deviated septum,
  polyp, scarring or other growth.

  This is apparently not a problem when you're not diving, but causes blockage due to pressure changes on
  descent and ascent. The lining of the blocked sinus is damaged by the pressure changes, resulting in
  swelling and hemorrhage and allowing a flare-up of any bacteria that might be lurking around in the

  The appropriate antibiotic depends entirely upon the type and kind of bacteria present—as determined by
  nasal cultures and sensitivities. Augmentin is a broad-spectrum antibiotic and should handle most
  bacteria of the kind living in the nasal cavity. However, some germs are resistant and this might cause
  your doctor to change to a more specific drug.

  This problem will continue until you find the cause and get it managed properly, possibly surgically.

What Caused My Nosebleed?

       Q: I have been certified for one year and have completed approximately 30 dives. I was recently diving and sometime
       in the middle of the week had a strange experience. I started my descent and at about 15 feet started to feel an intense pain across my forehead, around the top of my mask. I thought perhaps my head was sore from wearing my mask on consecutive days. I continued my descent, equalizing as I went, hoping it would stop and wondering if I should abort the dive. I do not recall having ear pain. By the time I got to 60 feet, the pain was gone.

       I followed my group for the drift dive and sometime later realized there was warmth around my nose and figured I
       had a nosebleed. Since it was not bothering me, I continued the dive. When we surfaced, my husband/buddy was
       shocked to see blood in my mask. He didn't want me to dive again that day, but I cleaned up on the boat, stopped the nosebleed and did the second dive with no problems.

       Do you have any idea what caused the pain? Should I have aborted the dive? Should I have done the second dive?

                                                                      via e-mail

       A: Severe headache and nosebleeds associated with diving are almost always due to sinus
       barotrauma. Bleeding can also be caused by trauma from squeezing the nose too tightly during
       attempts to clear the Eustachian tubes. The sinuses are air-filled and are subject to the same
       pressure changes of descent and ascent as the ears. If the sinus cannot equalize due to blockage
       of the ostium (opening into the back of the nose), there will be damage done to the vascular
       mucous lining of the sinus. For more on headaches while diving, go to

       You should have aborted the dive if you bled enough to be unable to see through your mask.
       Rarely do nosebleeds cause enough bleeding to become dangerous to a diver, and then only if
       associated with severe hypertension or blood vessel tumor. The decision to make the second dive
       is debatable in light of the volume of blood and the history of the first dive.

       If bleeding is persistent and heavy, then you should seek medical consultation from a
       diving-oriented ear, nose and throat doctor to check for other problems, such as septal deviation,
       polyps, hemangiomas or tumors. The hard part might be in finding a doctor who knows something
       about diving medicine. You can call DAN and request a referral (919-684-9111). 

Frenzel equalization method
I am interested in learning the Frenzel method of equalizing, when one forces the tongue toward the back of the throat while plugging the nose. Please explain the technique to me in a manner that would be useful for teaching.

via email
Miami, Fla.

You'll want to refer to "The Diver's Complete Guide to the Ear" in which we describe all the methods for equalizing your ears. The Frenzel maneuver described by DAN is: "Adding air to the middle ear by closing the nose, mouth and glottis voluntarily, then driving the tongue backward, which acts as a piston to compress air into the nasal cavities and through the eustachian tubes." In other words: Close your nostrils and the back of your throat, and thrust your tongue against the soft palate. This gently forces air through the eustachian tubes.

Can I Dive with a Cold?
I canceled a recent dive trip because I had a bad cold. Was that really necessary?

via e-mail

You probably did the right thing. Nasal congestion and blockage can lead to sinus and middle ear barotrauma. And the resulting sinus infections and middle ear damage and infections can cause hearing loss and balance problems. 

What Is the Treatment for Middle Ear Barotrauma?

Is there a specific treatment for middle ear barotrauma to help eliminate the pressure and fluid in the ear? How long does this generally last?

via e-mail

Barotrauma of the middle ear occurs from swelling and bleeding after the ear is damaged from a diver's inability to equalize pressures on descent or ascent. Treatment involves reducing the swelling, draining the serum and blood through the eustachian tubes, and treating any infection that occurs when the eustachian tubes are blocked.

This treatment generally consists of oral decongestants and antibiotics. Antibiotics are used only when there is fluid in the middle ear and there is the possibility of infection. If perforation is present, oral antibiotics should be used. Ear drops are not advised if there is perforation of the eardrum.

Middle ear barotrauma usually clears up anywhere from several days to six weeks, depending upon the degree of damage done and whether or not there is a perforation of the eardrum.

Divers with middle ear barotrauma should not dive until all symptoms have cleared. If there has been perforation, do not dive for at least six weeks after the perforation has healed. No ear drops should be used in the event of rupture, as damage can be done to the middle ear.

Diving and Tinnitus (Ear Ringing)
I have heard that ear ringing after a dive may be a sign of something. What?

via e-mail

Ringing in the ears or "tinnitus" is one of the most prevalent and bothersome of symptoms related to diving. Tinnitus may be caused by damage or disease anywhere along the path of the auditory system. In divers, it can be related to TM joint pressure from clamping down on the mouthpiece, wax buildup in the ear canal with tympanic membrane irritation, barotrauma to the middle and inner ear, decompression illness involving the inner ear or rupture of the round window with perilymph fistula. It is most often found in association with vertigo (dizziness) and there is usually some deafness.

During the last two decades, hyperbaric oxygenation therapy (HBO) has been used in the treatment of sudden deafness and chronic distressing tinnitus, with mixed results. It should be emphasized that this and other newer methods of treatment are still under evaluation. At this time there is no universal, symptomatic or specific treatment for tinnitus.

What divers can do:

    * Get a good examination by a diving-oriented ear, nose and throat doctor. The tinnitus may not be from diving at all. If it is related to diving, early treatment may be helpful.
    * Check out your regulator mouthpiece for fit. Consciously avoid clamping down on the mouthpiece. It may be that your dentist can help. Try this yourself—clamp down on your teeth and hear the high-pitched whine.
    * The use of nerve stimulants is to be avoided. Therefore, excessive amounts of coffee (caffeine) and smoking (nicotine) should be avoided. Aspirin is a common offender.
    * Learn as quickly as possible to accept the existence of the head noise as an annoying reality and then promptly and completely ignore it as much as possible.
* Tinnitus is usually more marked at bedtime, when one's surroundings become quiet. Use any kind of masking noise-maker that won't keep you awake.

Additional information can be obtained from the American Tinnitus Association (P.O. Box 5, Portland, OR 97207-0005).

On the web, go to:

Can I Dive After An Ear Operation?
I am 37 years old and have been diving for 12 years. I have completed just over 500 dives. Recently, I developed a ringing in my ears that specialists call otosclerosis. This ringing is not related to my diving. Instead, it appears to be a calcium buildup on one of my inner ear bones that is pushing the inner bones against my eardrum. This contact causes constant ringing.

The ear specialist said I could have an operation in which the problem bone and the calcium would be removed and replaced with a plastic bone. Most or all of the ringing would go away, but I'd never be able to dive again since the operation would involve cutting through my eardrum. The risk for further problems once you cut through the eardrum is too great, therefore I'd have to quit diving.

Is this true?

via e-mail

Otosclerosis is the abnormal growth of bone of the inner ear. This bone prevents structures within the ear from working properly and causes hearing loss and ringing. Otosclerosis usually affects the last bone in the chain, the stapes, which rests in the entrance to the inner ear (the oval window). The abnormal bone fixates the stapes in the oval window and interferes with sound waves passing to the inner ear.

In an operation called a stapedectomy, a surgeon (otolaryngologist or otologist) bypasses the diseased bone with a prosthetic device that allows sound waves to be passed to the inner ear. The problem for divers is that the pressure changes from clearing the middle ear can force the prosthesis through the oval window due to the lack of normal muscular support. This could result in permanent damage to the inner ear.

Unfortunately, I agree with the advice you received from your ear specialist. The risk of injury from pressure changes would be quite high and could end in permanent deafness or severe inner ear damage.

Can I Take Allegra and Dive Nitrox?
I occasionally take Allegra for an allergy. Can I take this drug and dive nitrox?

via e-mail

Allegra has none of the effects that mimic adrenaline and is safe to use with nitrox. It reduces the risk of oxygen toxicity, unlike some other allergy medications that may actually increase the risk of oxygen toxicity. Another point: Allegra has fewer sedative side effects than other allergy medications.

Prevent Ear Infections
I seem to be getting an ear infection after almost every dive. What can I do?

via email
Norfolk, Va.

Not all ear infections are the same, nor is all water that you dive in the same. I assume that your query concerns otitis externa, or infection of the ear canal. It may be that you haven't gotten rid of the first infection before you dived again. Sometimes these infections require a full 10 days of treatment with ear drops containing an antibiotic.

Ear canal infections can be easily prevented by the judicious use of ear drops after each dive. These drops are for changing the acidity and moisture of the ear canal so that organisms cannot survive. Cleanse external canals of occluding wax and avoid trauma from Q-tips, bobby pins, etc. Use a good ear solution to maintain a slightly acidic environment. SwimEar or Star Otic.

What Do You Know About Star Otic?
I read that Otic Domeboro is the best product for preventing swimmer's ear, but it's expensive and available by prescription only. Solutions containing alcohol are readily available, but irritate my ear. A "home brew" mixture is a possible alternative, but I don't think this a prudent alternative. I did some research and found a product called Star Otic. It is a Modified Burow's Solution (essentially Otic Domeboro) and is available over the counter for about $5. I tried it on a dive trip a few weeks ago, and it worked great. Is it OK to use?

via e-mail

Star Otic is an alcohol-free solution and contains Modified Burow's Solution, a mixture of aluminum acetate, acetic acid and boric acid in a propylene glycol vehicle. Cost is significantly less—$3.79 per 5-ounce bottle—and it's safe to use.

Incidentally, a homemade solution of half vinegar, half peroxide is safe and effective. For more information on ear drops, go to www.scuba-doc.com/otext.htm.

Exercise and Diving

How Will Exercise Affect My Diving Experience?

I am an extremely fit 62-year-old who regularly works out at my local gym. I am planning a trip to Grand Bahama Island and would like to continue my regular gym routines coupled with extensive scuba and skin diving. How much is too much? I have 40 years of diving experience, but this is the first time I will have the chance to experience virtually unlimited diving in warm water. What would you suggest?

via e-mail

First, congratulations on keeping yourself fit. This is something that you can continue to do on your dive trips, with certain precautions. The results of some studies suggest that the risk of neurologic decompression illness is reduced by physical conditioning, and the effect is independent of differences in age and weight.

You definitely should not exercise in the time period immediately after a dive while off-gassing or within several hours after a series of dives. Also, scotch any plan for mountain climbing immediately after diving.

If you exercise and plan to dive following the exercise, it would be wise to allow for a cool-down and rehydration period.

Can I Dive After Running a Marathon?
I'm running my first marathon this month in Maui. I'd like to dive a couple of days after the marathon. Can I?

via e-mail

Even if the race includes ascending to significant altitude, as might be the case on Maui, you can dive. Make sure you're completely rehydrated from your race, as dehydration is a real risk for decompression accidents. It is also recommended that you have a cool-down period of several hours between your dives and any strenuous activity.

You should not, however, run or hike to altitude soon after diving. Stay at sea level at least 12 hours after a single dive or 24 hours after multiday, repetitive diving.

When Is It Safe to Exercise After Diving?
Will the residual nitrogen in my system from a dive affect my cardiovascular system when I do an aerobic workout the next day?

via e-mail

We get asked this question a lot, especially from dedicated runners, swimmers, hikers and gym rats. It takes about 24 hours to eliminate residual nitrogen from your body. There is some debate about whether exercise, especially strenuous activities such as running or mountain climbing, is risky during that period of time. Those who advise divers not to exercise immediately after diving say that it might increase the chances of bubble formation from residual nitrogen levels.

The research on exercise after diving can be contradictory. There are some inconclusive reports that point to physical stress as the cause of DCS in some divers who exercise after diving. But there is also evidence that exercising while decompressing is helpful in reducing decompression accidents.

 Is Creatine Dangerous for Divers?

 Q. I have started a weightlifting program and am considering the use of creatine monohydrate as a
  supplement. I read that it's a "nitrogen-containing substance produced naturally in your body and is
  found in meat, poultry and fish." The scary words here, obviously, are "nitrogen-containing." Any
  worries that I'll increase my likelihood for getting bent if I use it?
via email, Ellicott City, Md.

 A.  Taking nitrogen-containing supplements will not affect your likelihood of developing decompression
  illness. In order to get bent, a diver has to have gaseous nitrogen in the tissues, and this is obtained
  from our breathing gas. Decompression sickness occurs when the tissues are saturated with nitrogen at
  depth and it comes out of solution as bubbles on ascent. The nitrogen in the supplements is molecular
  nitrogen and is not affected by the pressure changes of depth.

Eye Problems
Can Contacts Damage My Eyes While Diving?
My dive instructor says that pressure and dry air in a mask can dry out eyes, causing contacts to damage the eye. He says I should get prescription lenses. Is this true?

via e-mail

I'm afraid your dive instructor is wrong. The only real risk you run by wearing contact lenses under your mask is financial: If your mask floods, your tiny, transparent investments can be washed out of your eyes and into the great blue. Whether you decide to use prescription lenses or contacts is a personal preference. If your eyes are stable and your vision is not changing, the prescription lenses may be your best bet in the long run, though a corrective mask is useless before you put it on and after you take it off. With contact lenses, you never lose visual acuity, even on the boat. For more information, go to www.scuba-doc.com/diveye.htm.

Quick Tip: Diving with Contact Lenses

    * Wear soft contact lenses.
    * Because soft contacts are more susceptible to marine infection, use disposable lenses.
    * A good face mask seal minimizes the possibility of losing a lens during a dive.
* Use a purge-valve mask—with any luck, should you lose a lens, it will get caught in the valve and you can fish it out once you're back on the surface.

Will My Son's Eye Condition Prevent Him From Diving?
Our son was just diagnosed with an eye condition called keratoconus, a thinning of the corneal lens. According to the handouts given to us by his doctor, he can do sports activities as long as he wears protective eyewear. We're concerned about the pressure changes associated with diving. He is 13 years old and is about halfway through diving certification. That's on hold until we know more about the condition and how it relates to diving.

via e-mail

Your son can dive, depending on his visual acuity. Keratoconus is not affected by pressure and depth changes. The possibility of a mask squeeze is a concern and might be a hazard.

Keratoconus can be corrected with a rigid gas-permeable contact lens (or surgery). Unlike hard lenses, gas-permeable lenses—whether they're extended-wear or disposable—won't allow bubbles to get trapped between the lens and your eye.

Fear, Anxiety and Panic
I Want To Dive, But I'm Scared of Fish
I'd like to dive, but, believe it or not, I am scared of fish, even the tiny ones. Could I be a shark's next meal?

via e-mail

It's not a silly question. Whether or not you learn to dive depends mainly upon how severely affected you are by your fears of being harmed by some big fish or predator. If you cannot get these thoughts out of your mind while diving, then you may not be able to do the many tasks that you're expected to during a dive.

We become visitors in the ocean when we dive for very brief intervals. The fish live there all the time and it is their world. Very few of these creatures pay us any attention whatsoever, and if they do, it is usually to get out of our way. Shark attacks on divers are very rare. In fact, for the 10-year period from 1987 to 1997, DAN reported no deaths from shark attacks in its annual report on diving fatalities.

Flying, Altitude after diving?
What Is the Rule on Altitude and Diving?
After diving, what is the highest elevation we can drive to safely?

via e-mail

You should wait at least 12 hours after a single dive or 24 hours after multiday, repetitive diving to drive higher than 1,000 feet. If you can't wait, then you should treat your drive over mountains as you would a rescue flight (the Undersea and Hyperbaric Medical Society recommends waiting 12 hours). Rescue flights for people with a diving accident should not ascend higher than 1,000 feet, so that the victim is subjected to the least possible pressure reduction and to limit any further gas expansion. The same would apply to driving across a mountain range.

See http://www.scuba-doc.com/flyafdv.html and www.scubadiving.com/training/medicine/flying/.

Flying After Diving: Remember the Rules

       A few years ago, I took a dive trip to South Bimini. We
       dived on Friday, Saturday and Sunday morning (70-foot dive,
       then a 40-foot dive each day). Sunday afternoon, about three
       to four hours after we surfaced from the last dive, we took a
       charter flight back to Fort Lauderdale. The pilot asked us if we
       had dived that day and then wanted to know our profile. He
       said that he would "keep the ceiling below 1,200." When I
       mentioned this to a friend recently, she wondered why we
       didn't get bent. At the time of the flight, I assumed that we
       were safe. The plane was a small twin-engine Cessna, holding
       about 12 passengers. Were we in danger of getting bent?

                                            via e-mail

  Your pilot was probably correct in that your diving pattern had been
  relatively safe from the point of view of onloading nitrogen before the
  flight. We get bubbles when we:

       1. Ascend to the surface after a dive.
       2. Ascend to altitude after a dive (a continuance of the dive
       while flying).
       3. Ascend to a high altitude from the surface without

  Therefore, we need to allow a longer time to offgas nitrogen after
  diving (the same reason we spend a designated time on the surface
  between dives).

  To answer your friend's question, you didn't get bent because you
  didn't have very much nitrogen in your system and you didn't fly high
  enough for what you did have to come out of solution as bubbles.

  In two of his books on diving, Bruce Wienke says that we "should not
  worry too much about ascending to altitudes below 3,000 feet as far as sea level diving is
  concerned—corrections to ordinary protocols are minimal."

  The most recent guidelines concerning flying after diving are:

       A minimum surface interval of 12 hours is required before ascent in a commercial aircraft.

       Wait an extended surface interval beyond 12 hours after daily, multiple dives for several days or
       dives that require decompression stops.

       The deeper or longer the diving, the longer the duration recommended before flying.

  These guidelines are for recreational diving and should not apply to commercial diving or nitrox diving.
  Because of the complex nature of decompression illness and because decompression schedules are
  based on unverifiable assumptions, there can never be a fixed flying-after-diving rule that can guarantee
  prevention of bends completely.

  DAN is in the midst of a study concerning flying after diving. All reported cases of DCS after a single
  no-decompression dive have occurred when the pre-flight surface interval was 12 hours or less. After a
  repetitive dive, DCS occurred even at pre-flight surface intervals as long as 17 hours. The data so far
  suggest that the original recommendation of waiting 12 hours or more after making single
  no-decompression dives is reasonable. In addition, current research suggests that it may be wise to wait
  17 hours or more after making repetitive dives. However, the research is as yet incomplete and further
  work is continuing. 

Diving after flying?
When is it safe to dive after flying, especially if I had an alcoholic drink on the plane?

via email
Charlotte, N.C.

There are no guidelines concerning the time to dive after flying or having alcoholic beverages. However, mild dehydration can occur on long flights and alcohol consumption (and drinking caffeinated beverages) contributes significantly to dehydration. Dehydration is a definite risk factor in predisposing a diver to decompression illness because the washout of inert gas (nitrogen, in diving) is less effective in a dehydrated individual. There are few dive trips that don't start out with a complimentary rum punch (often provided by the dive operator), and one free drink often escalates into several—on top of what you might have had on the plane during the trip. There is a small uptake of nitrogen back to sea level partial pressure upon descent and exit from the aircraft. Residual nitrogen is referenced to nitrogen tissue levels above normal sea level values and a flight at 8,000 feet cabin altitude would result in lower tissue nitrogen levels than sea level. On descent, tissue nitrogen pressure would simply return to sea level amounts.

We should expect to see more decompression illness on the very first day of diving if there were a relationship between flying and drinking alcohol before diving. The Divers Alert Network (DAN) has reported some data suggestive of an increase in decompression accidents on the first day of diving of a trip. Their figures show that of the 88 cases reviewed from the Caribbean for 1994, 33—or 37.5 percent—occurred on the first day. The remainder occurred on days two through seven. These numbers are far too small to establish a cause and effect, but are suggestive. It would certainly seem reasonable to wait at least 24 hours before diving, rehydrating yourself as much as possible and avoiding overkill with the alcohol.

Free Diving
Is It OK to Free Dive After a Scuba Dive?

       During my instructor development course, I learned of a change to the PADI open-water
       training dive sequence: The optional open-water skin dive is now done after the last two
       open-water training dives.

       I thought free dives after scuba diving should be avoided because residual nitrogen in the
       tissues could be forced back into solution and become hazardous during the speedy ascent
       associated with free diving.

       If PADI has made a change to its training, has there also been a change in the school of
       thought about free diving after scuba?

                                                                via e-mail

  Important clarification: PADI does not specify that the optional open-water skin dive be done after the
  last open-water training dive. According to Brad Smith, PADI's manager of training and quality
  management, PADI recommends only that it's an optional skin dive, conducted at the instructor's

  As fas as your concerns about free diving after scuba diving, decompression illness from breath-hold
  diving does occur. Of particular relevance to the sport diver is what happens to the snorkeling breath-hold
  diver who repeatedly dives during the surface interval between scuba dives. Very little nitrogen is
  transferred from the alveoli to the blood during one breath-hold dive. However, repeated dives alter the
  off-gassing process, cause on-gassing and could completely change subsequent dive profiles. If you go
  snorkeling between scuba dives, you should stay on the surface.

  For more: www.scubamed.com/divess.htm#anchor447923 and www.scuba-doc.com/taravana.html

GI Problems
Diving on Hepatitis C Meds?

  I take interferon and peginterferon, both of which are used to treat hepatitis C. Should I be concerned
  about diving?

via email

  There are many different stages of hepatitis C, and it would be impossible to tell you whether you can
  dive without having access to your records and being able to examine you.

  Interferon can cause side effects that can mimic the symptoms of a decompression accident. These can
  include any or all of the following: flu-like symptoms, fatigue, muscle pain and joint pain. Skin problems
  can include hair loss and dry skin-problems that can be increased by sun exposure. It also causes some
  immuno-suppression, which subjects you to the possibility of marine infections that are not ordinarily a

  The liver is affected by hepatitis C and can enlarge significantly in the early stages of the condition. An
  enlarged liver greatly exposes you to the risk of traumatic rupture of that organ. Diving generally should
  depend on the extent of the liver involvement and should be monitored closely by your private physician.
  For more information about hepatitis C and diving, go to www.scuba-doc.com/hepc.html.

Help! Diving Gives Me Gas
After I dive, I often suffer from large amounts of upper abdominal gas and bloating. Is this normal? Should I eat or avoid eating certain foods prior to or after diving?

via e-mail

I can think of two things that cause gas and bloating in a diver:

    * Pressure from your wetsuit can cause gastroesophageal reflux, particularly if the suit fits poorly.

    * As you descend, you swallow some air while clearing. This air is not a problem at depth, but when you ascend, it enlarges and can cause pain and bloating.

You might want to try to clear using methods other than swallowing. There are medications that a physician can prescribe designed to help eliminate gas.

To read more on this, go to www.scuba-doc.com/hrtbrn.htm.

 My Ulcer Has Flared Up—Can I Dive?

       I was diagnosed with an ulcer that has flared up to the point where I have been put on
       Prilosec and another stomach medication. Can I go diving? What are the risks?

                                                                via e-mail

  Diving with an active ulcer is not recommended due to the increased possibility of stress and possible
  perforation. Perforation or other complications of ulcer (e.g., hemorrhage) would be especially disastrous
  if they were to occur in an area far from medical care.

  If your ulcer heals before your departure date, confer with your doctor about continuation of medication
  during your trip. Diving per se has no direct effect on the ulcer, one way or the other.

  For more information: www.scuba-doc.com/hrtbrn.htm.

Hematology Questions
 When Can I Dive After Being a Blood Donor?

       Q: I weigh 90 pounds and will be donating one unit of blood for use in an upcoming surgery. How long should I wait after
       donating before it is safe to scuba dive?

                                           via e-mail

       A: Every time you donate blood, a simple blood test is taken to determine your hemoglobin level and you can request the
       results. If the level is above 13 grams, then it would be OK to dive after the fluid volume has been replenished (24
       hours). If the hemoglobin level is below 13 grams, then the wait should be proportionate. A wait of eight weeks seems
       quite long, but that is the period of time it takes to renew red blood cells. The most important part of the blood to the diver
       is the red blood cell, responsible for the transport of oxygen to the tissues.

       There is a way to shorten the time interval before returning to diving after blood donation. Approximately 10 percent of
       body iron stores are removed with each donation. When appropriate, iron supplements can be prescribed for patients
       making donations to help increase red blood cell count. Also, there is a drug, Erythropoietin, that will stimulate the bone marrow.

       Blood donors sometimes experience anemia. For an in-depth discussion of the effect of anemia on divers, go to www.scuba-doc.com/overview.html.

       After your surgery, you'll also need to find out when to resume diving—which would vary according to

       the type of surgery, post-operative course and your surgeon's advice. 

 Can I Dive With Anemia?

  I have been diagnosed with a genetic type of anemia in which the part of my red blood cells that carries
  oxygen is abnormally small. This condition didn't stop me from pursuing a basic dive certification at the
  end of last summer. Now, I am gearing up for a season of diving. Is there any reason that I should be
  concerned about the anemia when I dive? Are there any precautions I need to take? Or, heaven forbid,
  should I find a new hobby?

                                                                     via e-mail

  People with anemia, whatever the type, really have an oxygen-carrying problem. You should not dive if
  the ability of the blood to transport oxygen and off-load carbon dioxide is compromised in any way. You
  can take a simple blood test to determine your hemoglobin level. If the level is above 13 grams, then it's
  OK to dive. Diving when your hemoglobin level is below 13 grams puts you at risk of hypoxia and loss of
  consciousness while under water, which could lead to drowning.

Can I Dive With Leukemia?
Two years ago I was diagnosed with hairy cell leukemia. Since treatment, my blood counts have been normal. I feel great and was diving before this was diagnosed, with no problems. Is there any reason for me not to be diving now?

via e-mail

Congratulations on having had a great response to treatment. You should seek a physician knowledgeable about dive medicine to recertify you as fit for diving. The doctor will pay special attention to immuno-suppression and/or bone marrow suppression from the medication—with the possibility of anemia and lowered white blood cell counts. If you're anemic, you should not dive due to the dangers of a low oxygen-carrying potential and hypoxia at depth. Hemoglobin levels below 12 Gm/dl are dangerous.

Pulmonary changes from anti-cancer medications should also be looked for. If you are taking any other medications, such as a blood factor that stimulates the production of white blood cells, there can be mild to moderate bone pain, which might be confusing if there were the possibility of a decompression accident.

With normal blood counts and no evidence of immuno-suppression, your physician should be able to certify you for return to diving.

Heart and Vascular Problems
Can I Dive After Coronary Bypass Surgery?
Last summer, I had coronary bypass surgery. We are planning a trip to Kauai and I want to know if it is safe for me to dive.

via e-mail

Patients who have had successful coronary bypass surgery, angioplasty or stents are generally given the OK to dive—if you heed a couple caveats and observe some limits on your diving.

As you probably have been told, you need to keep your weight and blood pressure under control and maintain an exercise program. You'll also need periodic exams by your physician. Take an exercise tolerance test. If you can exercise with no decrease in blood supply, chest pain or serious heart irregularity and have a normal blood pressure response, you can undertake limited sport diving—in warm water (wearing a 3mm wetsuit), at shallow depths (to 60 feet), in minimal current and with easy entry and exits.

I've Got a Weak Heart—Can I Dive?

       Q: My heart condition is called cardiomyopathy or "weak heart." I have gone from an output of 15
       percent to one of approximately 45 pecent. I am responding well to medication. I am fairly active
       in walking and swimming. The medications I take are Digoxin, Furosemide, Coreg and Diovan. I
       also take Rantidine for reflux and Imipramine for migraine headaches. I feel great and the only
       thing that slows me down a little is the Coreg. I hope I get a thumbs up for diving.

                                                                      via e-mail

       A: Given the information that you have provided I would be very reluctant to allow you to dive. This,
       of course, depends upon your personal physician and his assessment of your cardiac status, but
       you face several important obstacles:

            Increased risk of serious arrhythmias (cardiac irregularities) associated with cardiomyopathy.
            Immersion can cause divers with pre-existing heart problems to have incapacitating
            irregularities that could be fatal if they occur under water. With a history of having had an
            ejection fraction of 15 percent, you have serious heart disease—even though it's corrected by
            medications at this point.

            Coreg is a beta adrenergic blocker, and as such, blocks the normal response to emergency
            requirements of the body for increases in heart rate to fulfill metabolic needs—as in stress,
            exercise and panic responses. This has been known to lead to heart failure under water.

            Simple immersion can cause pulmonary edema in some people.

            Furosemide is a diuretic that can cause dehydration—a known risk factor for decompression

            Imipramine is an antidepressant that can cause drowsiness and sedation in some people.
            This is adverse to diving. Plus, it has other serious side effects such as confusion, sun
            sensitivity and neurological symptoms that can be confused with a decompression accident. 

Can I Dive With a Congenital Heart Condition?
I am 12 years old and have a congenital heart blockage. Does this prevent me from getting certified to dive?

via e-mail

Bad news: You probably should not dive. I assume you are referring to "aortic stenosis," a congenital obstruction that prevents blood from getting from the left ventricle of the heart into the aorta. Any degree of this condition, other than extremely mild, is a contraindication for diving because the heart is prevented from pumping blood during exercise, and pulmonary edema and fainting can ensue.

Hypertension and diving?
Can someone with hypertension go diving? I was on vacation and wanted to try scuba, but the operator wouldn't allow me to take lessons due to my "yes" to that question.

via email
Chesterfield, Mo.

Some divers who have hypertension that is well-controlled with medication, and who have no damage to the heart, brain, eyes or kidneys, can dive. They are usually admonished "not to dive too deep" by their physicians who know little about diving medicine. Cold water, heavy exercise and stressful situations can cause the blood pressure to rise precipitously, even in those on medication, and can result in heart arrhythmias, strokes or infarction. The biggest risk, however, is the strong relationship between hyperetension and coronary artery disease.

Although most hypertensive medications have little effect on diving, those that are called beta blockers can reduce the ability of the heart to respond to the stresses of diving, and can lead to heart failure. If you are not on beta blockers, have a normal blood pressure (below 140/90), and if you can pass the exercise treadmill test (13 METS, 4 on the Bruce scale), you should be allowed to dive.

However, this is subject to the approval and advice of your physician.

Can I Mix Hypertension Medication With Diving?
I have high blood pressure and am taking 10mg of Vasotec daily. I am also taking 10mg of Lipitor for cholesterol. I recently tried to take a resort course in Cancun, Mexico, but was denied because of the medications I am taking. I am currently taking a scuba class at my local community college. Can I dive while taking these medications?

via e-mail

People with controlled hypertension (less than 140/90) are usually allowed to dive if there is no damage to the eyes, brain, heart or kidneys. Hypertension affects whether a person can dive because it is a risk factor for coronary artery disease. For this reason, it is recommended that all hypertensives, and anyone over the age of 45, have physicals to ensure their fitness to dive. Divers should have an annual exercise stress test to make sure that they can exercise to a sufficiently high level to participate safely in diving. An acceptable, or satisfactory, result on a treadmill exercise stress test means that the person is able to complete at least six minutes of the standard Bruce protocol without chest discomfort or significant electrocardiographic (EKG) changes that would indicate coronary artery disease.

The type of medication prescribed to treat your hypertension must be factored into the decision. Of particular concern is the class of medications known as beta-blockers, which can limit your ability to achieve the level of conditioning necessary in an emergency situation, and diuretics, which can dehydrate you and increase the risk of DCS. Other anti-hypertensives have few adverse effects on the diver. Vasotec is an ACE inhibitor and has some significant side effects (listed at www.rxlist.com/cgi/generic/enalap.htm#sect-Contraindications). These include hypotension and cough in some people. This would not preclude diving if these are not severe. Lipitor has no side effects that would adversely affect diving (www.virtualdrugstore.com/cholesterol/atorvastatin.html).

Another concern is the type of diving you do. While it is certainly true that reef diving is less strenuous, and probably less dangerous than diving in cold water or swift currents, there is still some risk. Every dive must be considered potentially strenuous. You must have a sufficient amount of physical reserve beyond what the planned dive requires in order to cope with unexpected situations or changing environmental conditions. For this reason, I suggest that divers demonstrate that their hearts can handle more than the minimum amount of necessary exercise before being cleared for diving (13 Mets or 4-5 on the Bruce scale).

See your doctor, have a physical and an exercise stress test, and if you're cleared to dive, enjoy! 

Can I Dive With a Pacemaker?
I was born with a congenital heart defect between the ventricles and the atrium. I now have a pacemaker that regulates my heart at 60 beats per minute at rest. The maximum rate is set at 120 beats per minute, but that rate is uncomfortable for me and produces anxiety. Can I dive? Are there special considerations I should know about?

via e-mail

Generally, people requiring pacemakers should not dive because of their basic heart condition. Occasionally there are individuals with certain arrhythmias who have pacemakers who may dive. If no other heart disease is present, and the pacemaker is tested against pressure up to 130 feet and exercise tolerance is good, you might be able to dive. However, there are pacemakers that increase their rate when pressure is applied to the generator case, resulting in a heart rate inappropriate to the demand.

Unfortunately, it's impossible for me to advise you properly without a cardiologist's evaluation of your condition. For more information on pacemakers, go to www.scuba-doc.com/pace.htm.

Thrombosis in finger
I recently suffered a thrombosis in my finger. I spent five days in the hospital on Heparin (a blood thinning drug), and underwent a whole load of tests including an angiogram. Everything was fine. I now take an aspirin daily and have given up smoking. I asked the doctors if my condition poses any problems for diving and they said no, but I'm worried they really don't understand diving. Does it cause any problems? My second question is this—I had been diving six weeks prior to suffering the thrombosis. Could it have been an air embolism, rather than a blood clot?

London, England

It would be highly unlikely that this is due to gas embolism at this late date after diving. Your diving could possibly have something to do with the thrombosis, however, since cold will sometimes trigger a Reynaud's type phenomenon. Good to hear that your tests are all normal and that you have quit smoking. Diving with aspirin is OK, and possibly even acts as a preventive for decompression sickness.

Can I Dive with DVT?

       I recently started taking Coumadin for a deep vein thrombosis (DVT) in my leg. Will this
       medication affect my diving?

                                                                via e-mail

  Diving with DVT could be hazardous because of the constricting effect of dive equipment, belts and
  wetsuits on the superficial veins. The effect of weightlessness on peripheral blood flow is another
  unknown, with possible increased flow due to lack of gravity. Unfortunately, I know of no studies on this
  question. Immersion does cause a central migration of body fluid, thereby possibly lessening swelling of
  the tissues and the amount of blood returning to the veins.

  Secondly, the drug Coumadin is quite difficult to control and dangerous because it makes it possible for
  significant bleeding to be caused by very minor trauma. Barotrauma of the ears, sinuses and lungs can
  cause bleeding, which is not usually severe in the average diver. However, when taking Coumadin, this
  minor trauma can become life-endangering or at the least cause significant ear damage with possible
  hearing loss.

  For more information: www.scuba-doc.com/antcoag.htm.

Hyperbaric Oxygenation
Can an Unnecessary Chamber Treatment Be Harmful?

       If you didn't have decompression sickness and entered a recompression chamber for
       treatment, is it possible to have any medical problems due to entering the chamber when
       it was not needed?

                                                                via e-mail

  Treating decompression illness (decompression sickness and arterial gas embolism) is just one of the
  uses for recompression chambers. They are now being used to treat quite a few other illnesses. In the
  United States, chamber treatment is approved by Medicare for some 13 conditions.

  Being compressed in a chamber is in essence a "dry dive" without the dangers of being in a watery, alien
  environment. You would, however, be subjected to the same risks of barotrauma to air-containing body
  spaces and the possibility of ear, lung and sinus problems. If 100 percent oxygen were being used, you
  would also be at risk of oxygen toxicity if the oxygen intervals and pressure were not properly controlled.

  Some side effects of hyperbaric oxygenation treatment include seizures and lung damage from oxygen
  toxicity, finger numbness, inflamed middle ear and refractive changes in the lens of the eye. For more
  information, go to: www.scuba-doc.com/hbocont.htm

Marine Hazards
What Can I Do About a Jellyfish Sting?
I got stung by a man-o'-war jellyfish on my leg and treated it with vinegar and ice. Ten days later it became red and swollen and I broke out in hives. I've been told that the venom and stingers are still in me! What can I do?

via e-mail

Your continued problem may be due to several factors. First, you may still have some of the nematocysts in and on your skin. These will not only cause problems from the toxins but can cause an allergic reaction. Secondly, you might have developed a chronic dermatitis to the proteins and histamines in the toxin.

Dr. Bruce Miller, a consultant to "Diving Medicine Online," says that it would be wise for you to seek the advice of a dermatologist for possible systemic treatment with antihistamines or steroids.

For more information: www.scuba-doc.com/jelistngs.htm or www.scuba-doc.com/irritants.htm.

Stings and things
My wife and I were on a diving trip in Cozumel a few weeks ago. I got stung by something that I thought was fire coral (black with white tips) and later my wife got stung by some floating things (maybe jellyfish) while she was swimming. I had little, red, itchy dots on my hands that after two days turned into little blisters. My wife got little red spots on her hands and chest that basically look like red freckles. After three weeks, things only got a little bit better. What was it, and what can we do about it?

- via email, Los Angeles, Calif.

You could have brushed against some fire coral, though fire coral is usually reddish-orange with white tips. In any case, you were definitely stung by the nematocytes of a marine organism. The nematocyte is present in hydroids, fire corals, jellyfish and many other ocean creatures. It fires a toxic dart when it comes in contact with the skin, leaving a reddish welt that stings, burns and itches. Scratching, rubbing or applying fresh water makes more of the nematocytes fire and worsens the problem.

Your wife could have encountered sea bather's eruption or sea lice. This is caused by coming into contact with the larvae of the thimble jellyfish or nematocysts (the discharge from the nematocyte) from several other ocean organisms, which abound in Caribbean, Gulf of Mexico and Florida waters at certain times of the year. It usually has a local name, such as aqua mala, but is caused by the nematocytes of jellyfish, hydroids or anemones.

It most often affects the skin under the swimsuit, around the edges and in skin creases, and recurs if the suit is not rinsed properly.

Treatment of both your conditions currently includes taking an antihistamine for the itching and applying an over-the-counter hydrocortisone cream (0.5 percent) to the rash areas. More serious eruptions might require epinephrine, systemic steroids and steroid cream.

  Fire Coral Burn: Long-Term Effects?

       I got a fire coral burn about a week ago. I treated it with vinegar, meat tenderizer and
       cortisone. It seemed OK, but now the rash is back, with welts. I used vinegar again and
       Neosporin in case of infection. I also took an antihistamine pill. What are the long-term
       effects? Should I see a doctor?

                                                                via e-mail

  Coral can cause rashes from four sources:



       Allergic reaction

       Marine infection

  You seem to have a combination of the first three. The first-aid measures you took are appropriate for
  this injury. The vinegar is for deactivation of the nematocysts, but will not be effective after the first day
  or so. Good cleansing and re-moval of foreign bodies is very important and the cortisone cream is
  excellent for any ensuing inflammation. However, infected scrapes should have appropriate antibiotic
  coverage and tetanus antitoxin.

  Persistent difficulty usually is caused by foreign body particles related to the abrasion. A visit to a
  dermatologist might be the wisest (and eventually least expensive) course to take.

  For more information, go to:


Older Divers
Should Older Divers Restrict Their Depths
My doctor says that after age 50 you should restrict your maximum diving depth to 40 feet. He said there is a place in the base of your brain that retains some pockets of air that can affect your brain. I dive regularly and I am 68. Is this true?

via e-mail

It's not true. There are no air bubbles at the base of the brain, and diving after 50 years of age requires no depth restriction to 40 feet.

There is some indication that as we age we are more prone to a decompression accident, but this requires only a sensible reduction in depth and time at depth, with conservative ascents and safety stops.

Pulmonary Problems

Diving With a Chest Cold—Bad News
The night after my last two dives, I came down with a chest cold with a deep wracking cough. It got worse and worse for three weeks (despite antibiotics), and has developed into bronchitis and asthma, neither of which I've ever had in my 44 years. Is it possible I got a mild lung overexpansion injury on those dives that developed into this nasty lung infection? After this coughing and wheezing clears up, are there medical tests that can be done to make sure my lungs and airways are clear and I'm once again fit for diving?

via email
Berkeley, Calif.

It is likely that you were coming down with an upper respiratory infection prior to your dives and the dives had nothing to do with your serious problems with bronchitis and asthma. If you were breathing continuously during your ascents you should have had no problem with pulmonary barotrauma. Barotrauma doesn't bring about asthma; it's the other way around. Lung overexpansion injury would have caused other symptoms that would be readily apparent to your doctor.

There are documented cases of pulmonary problems from fungus, mold and bacteria that are in gear that has been kept in a moist environment without cleansing prior to diving. This would be worth checking into in your case since your illness seems to be more than just a common cold.

Finally, ask your doctor to check into the possibility of foci of infection in your nose and sinuses that might have been transferred to your bronchi and smaller airways by the positive pressure of the regulator. It also would not be wise to dive until this has been sorted out and you show no evidence of asthmatic bronchitis or small airway disease, again as determined by your doctor.

For more information:

What Causes a Wet Cough After Diving?
I am a new diver who has no history of asthma or any respiratory problems. During my fifth dive, in cold water (62F) at 35 feet, I became cold and developed a cough that was wet. On surfacing, my breathing was very wet and rattly for hours afterward and the cough persisted until the next day. This has not happened before. I am a healthy and fit 40-year-old woman.

via e-mail

What you are describing is most likely pulmonary edema, where the lungs suddenly fill with liquid. This is seen in patients with heart failure, though in swimmers and divers it is usually not associated with heart disease but with other factors. However, before you do any more diving it would be wise to visit a cardiologist and be sure that you don't have a heart problem that you don't know about.

Pulmonary edema is unrelated to gas embolism from pulmonary barotrauma or decompression accidents. Contributory factors include immersion in water (particularly cold water), heavy exercise, negative pressure breathing and predive fluid overload. Symptoms and signs usually resolve spontaneously over 24 hours. Pulmonary edema can recur, so you'll want to avoid the factors that can contribute to it.

For more information: www.scuba-doc.com/puledem.htm.

My Buddy Has a History of Lung Collapses—Can He Dive?

       Q: A close buddy of mine, who is sick of hearing all my cool fish stories, wants to get certified. However, he's had one of
       his lungs collapse twice in the last five years, most recently in November 1999. Can he dive if he gets clearance from his
       physician? If he can dive, how possible is another lung  collapse and are there any depth limitations?

                                          via e-mail

       A: I strongly recommend that your friend not dive. Points for him to consider very seriously:

            A primary collapsed lung (spontaneous pneumothorax) usually is caused by underlying cystic lung disease.

            There is a recurrence rate of 33 to 50 percent.

            A secondary collapsed lung is caused by many diseases affecting the lung (e.g., asthma, scleroderma, tuberous sclerosis). The most common underlying cause is chronic obstructive pulmonary disease (pulmonary emphysema).

            The air space around a collapsed lung occurring under water will increase in size on ascent, causing a serious
            emergency condition.

       Surgical procedures called pleurodesis (scarring the lung surface) and pleurectomy (excision of the pleura, a thin
       covering of the lungs) are commonly performed for recurrent collapsed lungs. There is a recurrence rate of 8 percent following pleurodesis. Recurrence is rare following pleurectomy. Even if recurrence of collapsed lung does not occur, the underlying cystic lung disease of the other lung remains, with the inherent danger now being pulmonary barotrauma with air embolism.

       The following are absolute contraindications to diving:

            Diving within three months after any type of collapsed lung.

            Spontaneous collapsed lung in beginners.

            Expert divers with recurrent collapsed lung after pleurectomy.

       Relative contraindications to diving include:

            Diving after three months since a collapsed lung (three years in case of spontaneous
            collapsed lung).

            Divers with normal pulmonary function (determined by a variety of tests).

       Encourage your friend to take up snorkeling so that he can enjoy the reef and seeing fish. If
       something happens, at least he'll be on the surface and won't drown or have gas embolism. 

What Are the Risks of Diving in Shallow Water?
Are there any risks associated with taking a scuba diving lesson in a 12-foot pool? Do the same rules concerning flying after diving apply?

via e-mail

There are some risks. A diver can suffer a gas embolism in as little as four feet of water. This happens when a diver ascends while holding his or her breath and has a collapsed lung.

While there is very little chance of a diver developing DCI from lessons in a pool, commercial divers who spend a great deal of time in shallow water or who make frequent repetitive dives in shallow water are at risk for DCI.

The risk to a diver who flies after short dives in shallow water is proportional to the time spent at depth and the degree of nitrogen saturation. If your dive sessions are lengthy, flying immediately after diving might place you at some danger of bringing bubbles out of solution during an airplane's ascent.

Sea Sickness

Non-Drowsy Seasickness Medication?

Can you recommend a seasickness medication that works but doesn't cause drowsiness?

- via email,  St. Petersburg, Fla.

It's difficult to say what would be the right medication for you, as there are so many variations in the way individuals respond to medicines. What works for one person might not work for the next, and what makes one person very sleepy might not make another person sleepy at all.

Having said that, it's hard to beat the scopolamine patch (available under the brand name Transderm Scop), which tends to treat seasickness effectively without causing drowsiness.

One feared effect of diving with the scopolamine patch has been that there would be an increase in the absorption of the medication from the patch due to increased pressure at depth. But I haven't been able to find evidence in any medical literature that would indicate that this is a problem or even that it happens at all.

It has been my practice to advise the use of the patch for several days before diving to ascertain the effect of the drug on the individual. This allows for reduction in the size of the patch in case of any unwelcome effects.

I Throw Up Every Time I Dive!

  I become nauseated every time I dive and throw up into my regulator. I feel like I have altitude
  sickness. What's causing this?

                                                                     via e-mail

  There could be several things causing your nausea:

       Swallowing air at depth while clearing your ears can cause nausea without other symptoms. This air
       enlarges on ascent and can produce nausea.
       Nausea without vertigo and occurring only during the dive can be caused by a hyperactive gag
       reflex from the regulator mouthpiece.
       Nausea with vertigo is usually caused by alternobaric vertigo from unequal pressures between the
       Surge or wave action under water can cause motion sickness, though you most likely would have
       had nausea on board the boat as well.
       Nausea can be a nonspecific symptom of a decompression accident to the inner ear, but would
       occur generally on ascent and would be associated with vertigo. 

End-of-the-Dive Nausea

I am a new diver who has made about 20 dives. About 75 percent of the time, I get nauseated at the end of a dive. This has occurred in fresh and salt water, shore and boat dives. I am a healthy male and work out five times a week. Any suggestions?

via email Birmingham, Ala.

What you are describing is possibly vertigo and may be due to some abnormal stimulus of the balance mechanism in your inner ear. This can occur from unequal pressures between your ears (alternobaric vertigo) or can be due to unequal temperatures in the ears (caloric vertigo). In addition, there are other possibilities, such as air swallowing with enlargement of the gastric bubble on ascent or carbon dioxide retention. Also, tight belts and gear and wave action at the surface cause some people to feel nauseated.

Since there are so many things that can cause these situations in divers, it would be wise for you to see a diving-oriented ear, nose and throat specialist for a checkup. If the exam is OK, then consider that carbon dioxide retention might be your problem, and alter your breathing patterns.

For more information, go to www.scuba-doc.com/entprobs.html.

Land Sickness? Sopite Syndrome? Mal de debarquement?
A Case of "Land Sickness"

Two years ago after a weeklong live-aboard trip, I experienced "land sickness"—some dizziness, feelings of motion and slight nausea for four days. I am going on the same trip again this month. Any tips on prevention?

-  via e-mail

We haven't heard it called "land sickness," but the situation you describe is an adaptation of the vestibulo-ocular reflex. When you get off a live-aboard, it can feel like you've just gotten off a spinning merry-go-round. This interesting phenomenon affects most astronauts and seafarers, at least to a small degree. The vestibulo-ocular reflex is a complex mechanism, but, basically, we'd have blurry vision if it didn't exist. This reflex is one of the most rapid, accurate and adaptive mechanisms in the body. It's what allows wild animals to stay fixed on prey while hunting at top speeds, Gail Devers to see the finish line while straddling hurdles at full stride and teenagers to see 'NSync on the stage while bouncing around during a concert. Your condition is a lingering effect of the constant visual motion you were used to on the boat and your body is taking a bit longer to return to normal. It can last up to several weeks. Unless prolonged or severe, it should resolve without treatment.

Spinal Cord Injury, Diving?
Is It Safe to Dive with a Spinal Cord Injury?
Nearly a year ago, I fell from a utility pole and sustained a serious compression/burst fracture of my T12 vertebra. After months of pain and physical therapy, I am back to work and trying to resume normal life. The only time I am truly free of pain is when I'm diving, but my doctor recommends that I discontinue diving. I get some carry-over relief after my dives that can last for days. Also, I take no medication for pain other than an occasional Tylenol. Is there therapeutic value from diving for people with similar injuries?

via e-mail

It is possible to dive after suffering a spinal cord injury, as long as there is no permanent damage. In your case, however, I agree with your treating physician. There are several concerns you should be aware of:

# A possible link between spinal cord decompression sickness after spine trauma.

# The disruption of blood supply to the area where the fractures occurred or surgery was performed—the formation of scar tissue and altered blood flow may not allow for the most effective off-gassing of nitrogen from surrounding tissue once it is absorbed during the dive.

# If there is any neurological damage and the diver suffers a spinal bend when diving, recompression treatment is likely to be more difficult and there will be greater residual deficit after treatment.

Surgery, Diving?

Can I Dive After Back Surgery?
I just had a back operation, and my doctor says no diving. Is he right?

via e-mail

Generally, a sport diver can return to diving after complete healing and no evidence of neurological deficits as determined by a good neurological examination. This, of course, depends upon the type of surgery, findings at surgery and a host of other intangibles that can only be determined by your surgeon or neurologist. Your doctor's advice not to dive could be based on sound surgical reasons or it could be simply due to a lack of information about diving fitness qualifications.

Divers with back problems require careful assessment keeping in mind the heavy lifting a diver may be required to do when out of the water. A person who has had successful surgery with a normal neurological exam can be acceptable to be certified as fit to dive.

There is some evidence that back surgery disrupts the venous plexus of vessels around the spinal cord. This has been posed as a possible problem with the accumulation of bubbles and subsequent DCS. However, this has not been proven.

For more information, go to:

How Soon Can I Return to Diving After Torn Cartilage Is Repaired?
I am planning to have an arthroscopy to repair torn cartilage in my knee. The orthopedic surgeon said I could return to diving after the incisions have healed (no scabs) or in two weeks, whichever is sooner. What's your opinion?

via e-mail

Two weeks is quite reasonable. Arthroscopy causes minimal trauma and very little alteration of the blood supply of the joint, thereby reducing the chance of joint damage from bubbles. The gas used during the operation in the joint is rapidly absorbed and poses no threat from barotrauma. You should record the degree of pain and discomfort in the knee before you dive in case there is any question regarding a decompression accident affecting the joint.

Diving After Hysterectomy— How Long Do I Have To Wait?
How long should I wait to dive after having a hysterectomy? What if any complications could arise?

via e-mail

It depends on the type of surgery you have—abdominal, which requires two incisions, or vaginal, which requires only the vaginal incision. Healing of these is highly variable but usually require six to eight weeks before returning to full activity. Couple this with the need for conditioning, complete wound healing and the possibility of need for blood regeneration, and a period of eight weeks would be advised before diving. A post-op hemoglobin determination should be performed, and if it shows you are anemic, you should have that corrected before you dive.

Complications might include wound disruption, hernia and hypoxia from anemia. There would be no effects from the increased pressures of depth. There might be an increased risk of deep vein thrombosis due to the increased coagulability following major surgery and tight- fitting gear and wetsuits, but this is conjectural.


Can I Dive After a Vasectomy?

What is the recommended recovery time before diving after a vasectomy?

via e-mail

A vasectomy is a simple operation that consists of a small scrotal incision and removal of a small section of the vas deferens. Diving can generally be resumed after these operations when the incision or incisions have healed without scabs, or when you are cleared by your surgeon. Diving itself will have no effect on your surgery nor will the operation have any effect on your diving.

Vasectomy Does Not Increase the Risk of Prostate Cancer

Researchers from the Fred Hutchinson Cancer Research Center investigated how a vasectomy impacts the risk of developing cancer. They interviewed and reviewed the medical records of 735 men with prostate cancer and 703 men without prostate cancer. They found that the percentage of men in each group who had vasectomies was similar. The evidence suggests that vasectomy is not associated with an increased risk of prostate cancer.

Cancer Epidemiology, Biomarkers & Prevention (October 1999)

Teen Divers
Do Teens Get DCS More Frequently?
I will get certified when I'm 15. My parents are worried about an increased risk of decompression sickness because of my age. Are their concerns valid?

via e-mail

Teens are not more susceptible to decompression accidents. There are several caveats, however. Boys this age have narrow hips and are vulnerable to weight belt slipping during suit compression, even at relatively shallow depths. Moreover, says Dr. Maida Beth Taylor, consultant to "Diving Medicine Online," boys fuse their epiphyses later than girls. The epiphyseal plates near the ends of long bones are the major sites of new bone growth during development, and are very susceptible to injury or damage. If a DCS event occurred, it would be more likely to damage long bone growth in a boy of 16 than a girl who has completed her skeletal development and growth.

Physical maturity is one thing, intellectual maturity is another. Being physically able and comfortable with the heavy gear can be a real problem with a child's buoyancy, one of the most important skills in safe diving. Having the mental capacity to understand the physics involved in safe diving and the appropriate maturity for the decision-making that is required for himself and for the possible rescue of his buddy is something that most 15-year-olds possess.

Except for these caveats, there is no evidence that diving would affect the 15-year-old diver any differently than adults.

For more information: www.scuba-doc.com/teens.htm.

 Keeping Kids Warm in Cold Water

       I own a dive facility in Canada. Now that there are courses designed for kids as young as
       10, how do we keep them warm enough in 60- to 65-degree water when they can't get
       themselves into a custom-fitted suit appropriate for our climate?

                                                                via e-mail

  You pose a very good question—and one that has other ramifications. There is no way possible for a
  10-year-old child to dive in cold water without having a custom-fitted suit. The dangers of hypothermia
  are already high in children, not to mention the difficulties with buoyancy and the wetsuit near the surface.
  Add these challenges to the other difficulties faced by a 10-year-old and you have a setting for disaster.

  Physically, the young diver should weigh a minimum of 108 pounds (50 kg) and be at least 60 inches
  (1.52 m) tall. Equipment must fit properly. He or she should be able to handle the bulky diving
  equipment and should be able to enter and exit the water without difficulty. Gear size can be reduced and
  smaller tanks utilized.

  Cold stress and buoyancy control pose special problems for a person of smaller stature, particularly on
  the surface in a suit. In addition, the child should be physically, mentally and emotionally mature enough
  to rescue a buddy in distress.

  For more information on issues affecting young divers, go to:



Travel Problems
How Do I Keep Bugs From Bugging Me?
What insect repellent do you recommend to prevent mosquito, sand fly and other insect bites? I collected over 30 bites in five days of otherwise great diving in the Dominican Republic, despite head-to-toe spraying with Off! insect repellent.

via e-mail

There are no repellents that are 100 percent effective in preventing insect bites; if you only got 30 bites in five days in the Dominican Republic, I"d say that the Off! was 95 percent effective. Your choices:

DEET: N,N-diethyl-3-methylbenzamide (better known as DEET) is the most effective and best-studied insect repellent currently on the market and is the active ingredient in Off! When DEET-based repellents are used in combination with permethrin-treated clothing (see below), protection against bites of nearly 100 percent can be achieved. Plant-based repellents are generally less effective than DEET- based products.

HourGuard: The 3M Company developed a slow-release, polymer-based product named HourGuard that contains 35 percent DEET; this is the repellent used by U.S. military personnel. It's distributed by Amway Corp.

Skin-So-Soft: No-see-ums and sand flies use a different method to achieve their blood-sucking—by chewing the skin with mouth parts and an anti-coagulant. This is the reason sticky skin creams are effective at preventing their bites. Avon Skin-So-Soft can be mixed with Off! in a spray bottle, and is fairly effective, though not 100 percent effective. Avon now markets products under the Skin-So-Soft label that contain an EPA-recognized repellent. These products have very short half-lives and are also effective against some mosquitoes.

Bite Blocker: Bite Blocker is a plant-based repellent that combines soybean oil, geranium oil and coconut oil in a formulation that has been shown to be nearly 100 percent effective against mosquito bites.

Permanone: Permethrin (one common brand name is Permanone) is usually sold as a spray; it does not use DEET or citronella. It is sprayed on clothing, insect nets and the like (it is not applied topically). Permanone is found in outdoor sports and fishing/hunting stores and catalogues.

Bug Spray Verdict

No repellents are 100 percent effective. See above to find out just what these strange substances are made of and how effective they are alone or in combination with each other.

Women and Diving
Is It Safe to Dive While Pregnant?
Can I dive while pregnant? I'm getting mixed advice.

via e-mail

The quick answer: Don't dive while you're pregnant. We don't have very good data showing that hyperbaric pressure harms the fetus, and in fact, there are case records of hyperbaric oxygenation treatment of pregnant mothers with carbon monoxide poisoning without adverse effect on the fetus. However, the fetus does not have the protection of the lungs in filtering out the bubbles as does an adult.

All we can say is to stop diving if you are or may be pregnant. If you intend to become pregnant, please stop diving first. This is difficult advice, and surely some depths and times and kinds of diving must be all right, but no one can yet be sure what is safe and what isn't. The only thing that's for sure—anyone who tells you that certain limits are safe for pregnant divers is guessing, and may very well be guessing wrong.

According to Dr. Maida Taylor, "In this litigious society, there is only one answer—no diving while pregnant or even trying to conceive. No major studies prove it unsafe, but the hazards are there."

For more about women and diving: www.scuba-doc.com/womdiv.html or www.diverlink.com/pregnancy.htm.

Breast feeding and diving?
I am breastfeeding my two-month-old infant and am planning my first weekend dive trip (I'll do four dives, average depth 80 feet) when my baby is four months old. I'll still be nursing then. I am a little concerned that nitrogen bubbles will get into my breast milk and cause possible harm to my baby.

via email
Naples, Fla.

There is some concern among divers who are nursing that their infants might be harmed by nitrogen bubbles in breast milk. Nitrogen does not seem to form bubbles in the milk located in the breast glands. Even if the nitrogen were in bubbles, it would do the infant no harm. Ingesting bubbles, even if microscopic, would in no way be harmful to the child, as they would reside in the gastrointestinal tract where gas is a prominent feature already.

However, there are other issues you should consider. Breast engorgement can occur during the dive excursion since I'm assuming you won't be able to breastfeed for at least several hours. This can be uncomfortable due to snug dive suits and gear straps. You may want to pack a breast pump so that you're able to alleviate any discomfort from engorgement.

There is also a possibility of transmission of marine pathogens from the nipple to the infant, causing a particularly stubborn infectious diarrhea. These same bacteria are fully capable of causing severe mastitis if the exposed nipple ducts and skin have any irritations or skin breaks.

Finally, Dr. Maida Taylor found that the combined energy expenditure of nursing and diving, and the associated dehydration related to immersion, caused a decrease in the amount of breast milk (Medical Seminars, 1998). Should this happen, be prepared to supplement with some formula approved by your pediatrician.

Given all these considerations, it might be wise to consider postponing diving until your baby is weaned.

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