scubadoc Ten Foot Stop

May 8, 2009

Several Articles About Diving and Exercise

Filed under: Article, Publication — admin @ 3:02 pm

March 4, 2009

Frequent Diving and Exercise Reduce Bubble Formation

Filed under: Article, Publication — scubadoc @ 11:12 am

Aviat Space Environ Med. 2009 Jan;80(1):15-9.

Bubble formation and endothelial function before and after 3 months of dive training.

Pontier JM, Guerrero F, Castagna O.

Medicine Department, French Navy Diving School, Toulon Army, France. jm.pontier@free.fr

INTRODUCTION: It has been suggested that repeated compression-decompression cycles reduce diver susceptibility to decompression sickness (DCS). This study examined whether intensive scuba dive training would reduce bubble formation and modulate endothelial function as shown by skin circulation.

METHODS: There were 22 military divers who were studied before and after a 90-d program of physical training and open-sea air diving (mean 67 dives total). Skin blood flow in the forearm was measured at rest (baseline), during post-occlusive hyperemia (endothelium-dependent vasodilatation), and with local heating to 42 degrees C (maximal vasodilatation). Subjects were also examined by pulsed Doppler for venous bubbles 30, 60, and 90 min after surfacing from a hyperbaric exposure to 400 kPa (30 msw) for 30 min in a dry chamber.

RESULTS: None of the divers experienced DCS during the training period. There was no change in weight, body mass index, maximal oxygen uptake, or endothelial function. Bubble grades by the Kisman Integrated Severity Score were significantly decreased immediately after the diving training period (3.6 +/- 9.2 vs. 16.4 +/- 14.3) and increased 3 mo after this period (10.3 +/- 13.9 vs. 3.6 +/- 9.2).

DISCUSSION: The results highlight that repeated scuba dives and regular physical exercise activity reduce bubble formation and probably have a protective effect against DCS risk. Although this phenomenon has been observed for decades, the mechanism remains complex and the results cannot elucidate the effects of physical exercise and NO production. Bubble formation could activate the stress response which could be the basis for diving acclimatization.

PMID: 19180853 [PubMed - indexed for MEDLINE]

May 5, 2009

Blood Donations and Diving

Filed under: Uncategorized — admin @ 4:48 pm

Divers often donate blood and need to know when to resume diving. This article is meant to provide information to help answer those questions. This information should apply to any type of diving since the effect depends on the hemoglobin in the red blood cell mass rather than the partial pressures of gases.

How long must a diver wait after blood donation before diving?

The donor’s body replenishes the fluid lost from donation in 24 hours. If not anemic (Hgb<12 Gm/dl)a person can dive in 24 hours after blood donation. It may take up to two months to replace the lost red blood cells. Whole blood can be donated once every eight weeks. The most important part of the blood to the diver is the red blood cell, responsible for the transport of oxygen to the tissues. The fluid part of blood is replenished in about one day. If the diver waits 24 hours and has a normal hematocrit, then diving should be allowed.

Red blood cells are perhaps the most recognizable component of whole blood. Red blood cells contain hemoglobin, a complex iron-containing protein that carries oxygen throughout the body and gives blood its red color. The percentage of blood volume composed of red blood cells is called the “hematocrit.” The average hematocrit in an adult male is 47 percent. There are about one billion red blood cells in two to three drops of blood, and, for every 600 red blood cells, there are about 40 platelets and one white cell. Manufactured in the bone marrow, red blood cells are continuously being produced and broken down. They live for approximately 120 days in the circulatory system and are eventually removed by the spleen.

Is there a way to donate blood products and still be able to dive immediately?

Yes, through apheresis. This is the process of removing a specific component of the blood, such as platelets, and returning the remaining components, such as red blood cells and plasma, to the donor. This process allows more of one particular part of the blood to be collected than could be separated from a unit of whole blood. Apheresis is also performed to collect plasma (liquid part of the blood) and granulocytes (white blood cells).

Is there a way to shorten the time interval before red blood cell replenishment after blood donation?

Yes – 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. Erythropoietin, a hormone, can also be given to stimulate the bone marrow into producing more red blood cells.


Undercurrent Online Update

Filed under: News, Publication — admin @ 11:03 am

U N D E R C U R R E N T   O N L I N E    U P D A T E
F O R    S U B S C R I B E R S

Undercurrent — Consumer Reporting for
the Scuba Diving Community since 1975
www.undercurrent.org

Dive News

May 4, 2009

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Updates on Swine Flu In Mexico: Since it has shown up on the Yucatan peninsula, divers with Mexican travel plans need to stay current. Two good sites to check for the latest information: the U.S. State Department has created a “Swine Flu Alert” page (http://travel.state.gov/travel/cis_pa_tw/pa/pa_3028.html — if this link doesn’t work,follow the link at http://travel.state.gov) to give up-to-the-minute travel information, and the Centers for Disease Control is doing the same regarding health and medical information (http://www.cdc.gov/swineflu/). By the way, if you buy travel insurance early on in your trip planning, you’ll find many policies will allow you to back out for epidemics. If you try to add it later in your plans, you’ll probably be out of luck.

Recall On Mares Drysuit Hoses: Swedish dive gear maker Si Tech is recalling its low pressure inflation hoses that are used in Mares drysuits. The plastic flow-restricting insert (colored blue, black or green) in the hose may dislodge from the connection valve, potentially obstructing the air flow. Affected hoses were sold between 2006 and 2009 in 15 types of Mares drysuits, including the Dryfit, Icefit and Polarfit models. Send the recalled inflator hoses back to the dealer you purchased your drysuit from, or to a Mares’ service center, so the insert can be removed free of charge. For more information, contact Mares Customer Service at 203-855-0631 or e-mail mares@us.mares.com.

Diving Southeast Asia: This just-published, 302-page, soft-bound guide by Beth and Shaun Tierney, is a must for anyone contemplating diving in Indonesia, Malaysia or Thailand. Where is Sipadan? Raja Ampat? Komodo? Richeliu Rock? Maps make it easy to pinpoint dive destinations and travel routes. Destination and 250 dive site descriptions (with tables on depth, visibility and currents) help you determine whether you’ll see big fish in the blue or pygmy seahorses in the muck. There’s a lot of supplemental information such as travel tips, health tips, and resorts and liveaboard descriptions. Order at Undercurrent, get the best price Amazon has to offer and our profit will go to preserving coral reefs.

Save Lots On A Trip To The Caymans: From June 1 to September 7, Cayman Airways is letting kids under age 11 fly free on flights from Miami, New York or Tampa. More than 25 hotels and condos will give a free fifth night to families who book four nights, and 14 dive operators offer free diving for kids ages 12-17 and discounts on dive packages or above-the-water attractions. Go to http://www.caymanislands.ky/summersplash/offers.aspx. Other deals: The posh Westin Casuarina Resort on Grand Cayman is dropping its rates by 40 percent between June 1 and September 6; room rates start at $159. http://specialoffers.starwoodhotels.com/Westin_Casuarina_Grand_Cayman/so.htm?IM=PP_LHN_SOP_US_WI_1095&

Check This Video: Londoners were bewildered when 30 people in full dive gear were spotted walking around the city — in flippers — in late April. They were “frogmen” hired by British TV studio Sky to congregate in “flash mobs” throughout London to raise awareness of Earth Day and what people, even non-divers, can do to reduce climate change. Here’s the YouTube video of the frogmen giving eco-friendly advice (although they probably should have taken the snorkels out of their mouths before speaking): http://www.youtube.com/watch?v=RzeomVC2n1k&feature=player_embedded

Dive Operators and Instructors, We Need Your Help: Reader Mike Boom suggested an interesting spin on our Reader Reports — ask the dive operators for reviews. “One of my favorite conversations with a dive boat or dive resort manager is to ask about the worst or weirdest customers they’ve had. That’s when the really funny stories come trotting out, like the nudist dive charters, the Russian mafiosos with prostitutes in tow, animal pesterers who get bitten in return.” So, dive operators and instructors, turn the tables and tell us your entertaining stories that would amuse and inform our readers. E-mail me at EditorBenD@undercurrent.org, and we’ll compile the tales for an upcoming issue.

Florida’s Breakers Reef Recovering Nicely: In our December e-mail, we reported how a tugboat line caused extensive damage to Palm Beach’s popular Breakers Reef. Marine experts thought it would take 100 years for corals to grow back but just a few months later, they announced the corals are recovering much faster than expected. That’s because the reef corals were scrapped clean off, making it easier for a group of volunteer divers from local engineering and environmental firms to re-attach over 130 hard corals and other organisms back in place, and they expect close to 100 percent survival. The West Palm Beach Fishing Club is taking donations to support these efforts; get details by phone at 561-832-6780 or send an e-mail to Bill Fay, the diver leading the restoration, at bfay@appliedtm.com.

Lobsters and Crabs Do Feel Pain: A study to be published in the journal Animal Behavior says crustaceans do feel pain and stress, adding to growing evidence that all animals, even shellfish, can suffer. Lead author Robert Elwood collected hermit crabs from rock pools in Northern Ireland and gave some of them small electric shocks. When he provided vacant shells, only the shocked ones left their old homes for them, showing stress-related behaviors like grooming their abdomens and rapping them against the shell. “Grooming is a protective motor reaction, like licking a burnt finger, and viewed as a sign of pain in vertebrates,” Elwood wrote. The fact that they showed signs of physical distress at the same time they changed a behavior — moving into another shell — suggests they feel pain, too. All the crabs survived and were put back in the rock pools.

Send Me Your Reader Reports: Filing one gives you a chance to relate your experience, address your fellow divers, air a complaint, give deserving operators a pat on the back, and hit the highlights of a recent trip. And of course, your comments will be posted on our website and in our 2010 Travelin’ Diver’s Chapbook. Complete the online form on Undercurrent by clicking on “Submit a Reader Report.” Or send you report in an e-mail or as an attachment to us at ReaderRpt@undercurrent.org. Submit reports for trips you’ve taken after July 2008, and don’t forget to put your name on the report.

Coming Up In Undercurrent: Wananavu Beach Resort, Fiji: an updated report on this divers’ favorite . . .why travel insurance is so important for your next dive trip overseas . . . . . should you sauna before a dive? . . .a new study shows what’s lurking in that rinse tank . . . where Hawaii’s fish have gone – it’s not just the fishermen taking them . . . how and where you can recycle used scuba gear . . . a double fatality in Cocos Island leads to a major lawsuit ruling for the dive industry . . . and much more

Ben Davison, editor/publisher
Contact Ben

May 3, 2009

Nitroglycerine Reduces Bubble Formation In Wet and Dry Dives

Filed under: Article, Publication — admin @ 8:15 pm
1: Med Sci Sports Exerc. 2006 Aug;38(8):1432-5.

Exogenous nitric oxide and bubble formation in divers.

Departments of Physiology, University of Split School of Medicine, Split, Croatia. zdujic@bsb.mefst.hr

PURPOSE: Prevention of bubble formation is a central goal in standard decompression procedures. Previously we have shown that exercise 20-24 h prior to a dive reduces bubble formation and increases survival in rats exposed to a simulated dive. Furthermore, we have demonstrated that nitric oxide (NO) may be involved in this protection; blocking the production of NO increases bubble formation while giving rats a long-lasting NO donor 20 h and immediately prior to a dive reduces bubble formation. This study determined whether a short-lasting NO donor, nitroglycerine, reduced bubble formation after standard dives and decompression in man. METHODS: A total of 16 experienced divers were randomly assigned into two groups. One group performed two dives to 30 m of seawater (msw) for 30 min breathing air, and performed exercise at an intensity corresponding to 30% of maximal oxygen uptake during the bottom time. The second group performed two simulated dives to 18 msw for 80 min breathing air in a hyperbaric chamber, and remained sedentary during the bottom period. The first dive for each diver served as the control dive, whereas the divers received 0.4 mg of nitroglycerine by oral spray 30 min before the second dive. Following the dive, gas bubbles in the pulmonary artery were recorded using ultrasound. RESULTS: The open-water dive resulted in significantly more gas bubbles than the dry dive (0.87 +/- 1.3 vs 0.12 +/- 0.23 bubbles per square centimeter). Nitroglycerine reduced bubble formation significantly in both dives from 0.87 +/- 1.3 to 0.32 +/- 0.7 in the in-water dive and from 0.12 +/- 0.23 to 0.03 +/- 0.03 bubbles per square centimeter in the chamber dive. CONCLUSION: The present study demonstrates that intake of a short-lasting NO donor reduces bubble formation following decompression after different dives.

PMID: 16888456 [PubMed - indexed for MEDLINE]

Benefit from surfactant on eustachian tube function in divers?

Filed under: Article, Publication — admin @ 8:06 pm
1: Mil Med. 2008 Dec;173(12):1225-32.Links

A pilot study evaluating surfactant on eustachian tube function in divers.

Naval Submarine Medical Research Laboratory, Naval Submarine Base New London, Box 900, Groton, CT 06349-5900, USA.

BACKGROUND: Middle ear barotrauma (MEBT) is the most common medical complication in diving, aviation, and hyperbaric medicine. Eustachian tube dysfunction (ETD) quantifies the inability to open the eustachian tube (ET), risking MEBT. Surfactant administration improved ET function and efficaciously treated otitis media in a host of animal models. We performed a pilot study evaluating the efficacy of intranasal surfactant administration in reducing MEBT in repetitive diving. METHODS: Eight divers participated in a subject-blinded, placebo-controlled, random order, multiarm (air and O2)-repeated measures trial investigating the relative efficacy of intranasally administered surfactant, acetylcysteine and oxymetazoline, and orally administered pseudoephedrine versus saline-placebo in middle ear equilibration during repetitive, multiday diving. Subjects were tested with the Nine-Step Inflation/Deflation Tympanometry Test (NSI/DT) and sonotubometry (testing eustachian tube opening pressure [ETOP]) before and immediately after each dive. RESULTS: Significant interaction effects were found for drug-by-test (F8,668 = 4.05; p < 0.001) and the three-way interaction of drug-by-dive-by-test (F16,668 = 2.47; p = 0.001) in sonotubometry testing. The ETOP revealed trends toward lowered (improved) values post-versus predive in all treatment arms, which was significant for oxymetazoline (p = 0.04). Only four of the eight subjects experienced any holds during diving. Statistical analysis of the NSI/DT data showed that none of the drug interventions resulted in improvements in ET function over that expected by chance. CONCLUSIONS: There is large intra- and intersubject variability in daily functioning of the ET as measured using the NSI/DT and sonotubomtery (ETOP). Sonotubometry engendered trends toward lowered (improved) values post-versus predive in all treatment arms. The repetitive dives did not result in a significant decrease in ET function as evidenced in the saline-placebo trials, circumventing an ability to detect superiority among the various treatment arms in our subject population. Additionally, since our study was underpowered to detect significant effects, we can only assert that various inhalational agents may improve middle ear ventilation in repetitive diving warranting further study. A larger subject population including subjects diagnosed with ET dysfunction may provide more statistical power to discern the benefit of inhaled agents as a useful prophylactic for preventing or reducing ET dysfunction during diving and/or hyperbaric/hypobaric pressure changes.

PMID: 19149344 [PubMed - indexed for MEDLINE]

Polish Article on Treatment of Decompression Illness

Filed under: Article, Publication — admin @ 8:02 pm
1: Int Marit Health. 2008;59(1-4):69-80

Recompression treatment for decompression illness: 5-year report (2003-2007) from National Centre for Hyperbaric Medicine in Poland.

National Centre for Hyperbaric Medicine, Institute of Maritime and Tropical Medicine in Gdynia, Medical University of Gdańsk, Poland. jkot@amg.gda.pl

A serious diving accident can occur in recreational diving even in countries where diving is not very popular due to the fact that diving conditions there are not as great as in some tropical diving locations. The estimated number of injured divers who need recompression treatment in European hyperbaric facilities varies between 10 and 100 per year depending on the number of divers in the population, number of dives performed annually, and number of hyperbaric centres in the country. In 5 years of retrospective observation in Poland (2003-2007) there were 51 cases of injured recreational divers recorded. They either dived locally or after returning home by air from a tropical diving resort. All of them were treated with recompression treatment in the National Centre for Hyperbaric Medicine in Gdynia which has capability to treat any patient with decompression illness using all currently available recompression schedules with any breathing mixtures including oxygen, nitrox, heliox or trimix. The time interval between surfacing and first occurrence of symptoms was significantly lower in the group of patients with neurological decompression sickness or arterial gas embolism (median 0.2 hours) than in the group of patients with other types of decompression sickness (median 2.0 hours). In both groups, there were different types of recompression tables used for initial treatment and different number of additional sessions of hyperbaric oxygenation (HBO) prescribed, but the final outcome was similar. Complete resolution of symptoms after initial recompression treatment was observed in 24 cases, and this number was increased to 37 cases after additional HBO sessions (from 1 to 20). In the final outcome, some residual symptoms were observed in 12 cases. In 2 cases initial diagnosis of decompression sickness type I was rejected after initial recompression treatment and careful re-evaluation of diving profiles, risk factors and reported symptoms.

Scuba Diving and The Older Diver

Filed under: Article, Publication — admin @ 12:18 pm

The Older Diver

Problem — The Older Diver
To my knowledge there is no specified age limit to sport diving.

Diving Concerns

* Condition Related

Most elderly divers are not capable of sustaining the work load required by all but the least physically demanding dives. The majority of elderly divers do not exercise regularly or adequately.

* Treatment Related

Physical training can definitely minimize the decline in physical capacity in older divers.

* Diver Related

Chronological age and physiological age can differ markedly; and each individual ticks to his own genetic clock.

Risk Assessment

* Risk from the Condition

General health, agility and stregth decrease with age. Maximum heart rate, oxygen uptake and lung compliance decrease with age. [Parker, 'The Sport Diving Medical']
Good screening is necessary. Older divers have a higher incidence of chronic diseases; i.e., cardiovascular disease and chronic lung disease. Appropriate screening evaluations of the heart and coronary arteries with exercise testing is useful in older divers before instituting a diving program.
Osteoporosis (men and women) increases with age and increased incidence of fractures becomes a factor.

* Risks from treatment

The older diver is more prone to be taking multiple drugs and medicines, some of which have effects that are adverse to diving. These should be listed and evaluated prior to allowing diving. See web page at http://scuba-doc.com/drugsdiv.htm .

* Risks to the Diver

–Atherosclerosis affects the blood flow to the brain, heart, kidneys and limb muscles and therefore the function of these organs.
–Inability to self rescue due to decreased strength from muscle atrophy would be an important consideration.
–The older diver is more prone to hypothermia due to decreased tissue perfusion, decreased fat stores and decreased metabolism.
–Decompression sickness increases with age. [Edmonds] This may be due to decreased tissue perfusion and arthritic changes in the joints.

Advising the Diver

Most very old divers arrange for a personal dive guide to assist them in suiting up, donning gear, managing their entrances and exits from the water and accompanying them during the dive. The problem comes in getting the elderly to recognize when the time comes to ask for help! It’s hard to get an old diver out of the water!

* Potential for injury from future diving

Myocardial infarction, heart failure account for a high percentage of deaths while diving. [Caruso]
Increased risk of pulmonary edema [additive effects of pulmonary edema of diving with borderline heart failure from intrinsic heart disease.
Increased risk of fractures [hip]
Increased risk of decompression sickness
Inability to self rescue or manage unexpected water movements [current, surges, wave action].

* Modifiers

Regular Checkups.
Good physical conditioning
Absence of cardiovascular-pulmonary disease
Mentally alert
Diving Experience
Alteration of diving profiles with shallower, shorter diving, longer and deeper safety stops and longer surface intervals

* Dive or not dive

If an older diver is in good physical condition and is mentally alert enough to do adequate problem solving at depth, then I would personally have no qualms in certifying him to dive. The older diver is more likely to take fewer chances and to obey the rules. There are few 70 year-old ‘Buccaneers’!
Genetic clocks

To my knowledge there is no specified age limit to sport diving. Chronological age and physiological age can differ markedly; and each individual ticks to his own genetic clock. This having been said, most elderly divers are not capable of sustaining the work load required by all but the least physically demanding dives. The majority of elderly divers do not exercise regularly or adequately. Physical training can definitely minimize the decline in physical capacity in older divers.
Good screening necessary

Older divers have a higher incidence of chronic diseases; i.e., cardiovascular disease and chronic lung disease. Atherosclerosis affects the blood flow to the brain, heart, kidneys and limb muscles and therefore the function of these organs. Appropriate screening evaluations of the heart and coronary arteries with exercise testing is useful in older divers before instituting a diving program.

“I’m gonna live (dive) forever!”

If a 90 year old is in good physical condition, able to perform self and buddy rescue and is mentally alert enough to do adequate problem solving at depth, then I would personally have no qualms in certifying him to dive.

Ask for Help

Most very old divers arrange for a personal dive guide to assist them in suiting up, donning gear, managing their entrances and exits from the water and accompanying them during the dive. The problem comes in getting us old GCFD’s (“geezer-codger-fogy- duffers”) to recognize when the time comes to ask for help! It’s darned hard to get an old surgeon out of the O.R. – but doubly hard to get an old diver out of the water!

Older-Safer!

The obverse may also be operative; the older diver is more likely to take fewer chances and to obey the rules. There are few 70 year-old ‘Buccaneers’!

May 1, 2009

Pulmonary Barotrauma

Filed under: Article, Publication, Uncategorized — admin @ 10:01 am
ScenarioA 25 year old divemaster made one dive to 40 feet for 38 minutes and then spent 3 hours and 45 minutes on the surface. His second dive was to 55 feet for 27 minutes, at the end of which he struggled with a heavy anchor, swimming with it to the surface. At the surface he raised out of the water, yelled, became comatose and was pulled from the water. apparently convulsing. He was placed in the head low position, given O2 by mask and on arrival at a recompression chamber 50 minutes later, he was alert, oriented and really felt well. He complained of a slight numbness of both right extremities but otherwise had a normal exam. Is this DCS, epilepsy or pulmonary over-pressure? What is the one clue you need to make the diagnosis?

This diver obviously had a pulmonary overpressure accident with arterial gas embolism and was treated by placing him on Table 6A ( 165 feet for 30 minutes) and then on Table 6. The fact that it occurred immediately on surfacing indicates that it’s not DCS and surely a person with epilepsy should never have been certified as a divemaster.


Prevention

This episode underlines the potential risk of pulmonary overpressure accidents on every compressed gas dive regardless of depth and time. Prevention of pulmonary overpressure accidents starts with a good diving physical exam to ensure no history of pulmonary pathology which would prevent free pressure equilibration of all parts of the lungs as well as psychological evaluation of propensity to panic. The scuba instructor has in his hands the final prevention by teaching the dangers of breath-holding.


Mechanisms of Action

The mechanisms that occur when a pulmonary overpressure accident occurs are directly related to Boyle’s Law, and the greatest danger is at shallow depths-with the greatest gas volume expansion near the surface. Boyle’s Law states that with the temperature constant, the volume of a gas is inversely proportional to the pressure. When pressure differential between gas in alveoli and water (or chamber gas pressure in a compression chamber) exceeds 50-100 mmHg (3 to 5 FSW),free gas can be forced across the fine alveolar membrane into pulmonary interstitial tissues, pulmonary capillaries or rarely through the path of greatest resistance, the visceral pleura.


End Result
The results of this air movement across
these natural barriers are:

    • 1). Arterial gas embolism,2). Mediastinal and subcutaneous emphysema, and
      3). Pneumothorax.

Arterial gas emboliArterial gas emboli arise in the gas bubbles in the pulmonary capillaries -> pulmonary veins to the left side of the heart->possible coronary artery emboli or internal carotid and vertebro-basilar arteries to the brain-> cerebral artery embolism with the clinical picture of a stroke.

The clinical manifestations of cerebral gas embolism include a sudden onset of unconsciousness associated with a generalized or focal seizure. There is often confusion, vertigo and cardiopulmonary arrest. In a series of 24 USN cases in which the time was known, 9 occurred during ascent in the water, 11 within one minute at the surface and 4 occurred within 3-10 minutes at the surface.

Other clinical manifestations include the sudden onset of hemiplegia, focal weakness, focal hypesthesia, visual field defect, blindness, headache and cranial nerve defects. The operative word here is “sudden”-nearly all of these symptoms can also be caused by neurological decompression sickness. Less common manifestations are chest pain and bloody, frothy sputum.

An Unusual Case of Cerebral Gas Embolism
A snorkeler takes a breath from a compressed air regulator at depth.


Emphysema

Mediastinal and subcutaneous emphysema, due to bubbling in the tissues, cause substernal pain, subcutaneous crepitus (a crunching feeling ), a definite x-ray appearance and occasionally circulatory embarrassment (rare).


Pneumothorax

Pneumothorax occurs when the visceral pleura is ruptured by the air pressure and the lung collapses. When this occurs there is pain, decreased respiration on the affected side, changes to auscultation and percussion on physical exam with typical x-ray findings. If the opening is large-a tension pneumothorax can occur, requiring tube decompression of the chest before treatment with the compression chamber.
Spontaneous pneumothorax


Precipitating Factors

All of these things can happen when two precipitating factors occur:

1). Breath-holding ascent

2). Local air trapping

A breath-holding ascent occurs in association with panic, buddy-breathing and acute laryngospasm (a breath of sea water). Local air trapping is the result of bronchospasm (asthma), mucous plugs (post-bronchitis), blebs (blisters on the surface of the lung), air-containing pulmonary cavities(as in scarring from TB), and very often no reason whatsoever.

Sarcoidosis
Marfan’s Syndrome
Cystic Fibrosis
Asthma


Treatment

Treatment of these three entities varies from the simple ( bedrest, O2, and observation for the emphysema) to immediate compression to 6 ATA and resuscitation while in transport for the arterial gas embolism. A chest tube is standard care for pneumothorax with a good neurological exam to rule out cerebral embolism.

Compression takes precedence over treatment of the pneumothorax and mediastinal emphysema and frequently attendants must also treat coexistent near-drowning, using endotracheal tube, 100% oxygen and IV fluids and dexamethasone.

Our young divemaster had a close encounter with the ghost of Sir Robert Boyle when he apparently held his breath while straining to swim to the surface with the anchor. The lessons of this episode should be readily apparent and can be acted upon by all of us, no matter how experienced we think we are.

*Reducing Risks of Pulmonary Barotrauma



Coxson HO, Rogers RM, Whittal KP, et al: A
Quantification of the Lung Surface Area in Emphysema Using
Computed Tomography. Am J Respir Crit Care Med
159(3):851-856, 1999.
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