Physics & Gases

SCUBADOC Diving Medicine Online

Carbon Monoxide

Carbon monoxide poisoning is a rare cause of problems when diving, it does occur when there is contaminated air in recreational diving tanks. CO poisoningis the leading cause of poisoning deaths in the U.S.(about 8600 deathsper year) and is easily missed unless health care providers are especiallyvigilant. The most commonly observed result related to CO […]

High Pressure Nervous Syndrome

Helium During the 1930’s the U.S. Navy tested other gases as a substitute for nitrogen. Their scientists conducted experiments using rare gases such as helium, neon, and argon. After numerous trials, helium was selected as the most suitable gas to dilute oxygen for deep diving. Helium is the second lightest element known to man; in […]

Entonox Dangers

Warning! ENTONOX NOT to be used in divers suspected of a decompression accident!! Here is a recent correspondence that I feel should be passed on: Question: This topic came up during a discussion on paramedic ‘routine’ treatments where it was said by the paramedics that Entonox was a routine treatment for accident victims and that […]

Breath-hold Diving: Taravana

Taravana, What is it? Taravana, a condition first observed by E.R. Cross in 1958, and reported in 1958- is a diving syndrome seen in working Tuamotu Island natives diving the Takatopo Lagoon. The word apparently means ‘to fall crazily’ and is thought to represent decompression illness in these divers. P. Paulev, a Danish naval officer […]

Free Diving and Shallow Water Blackout

SHALLOW WATER BLACKOUT (Latent hypoxia) Shallow water blackout (SWB) is the sudden loss of consciousness caused by oxygen starvation following a breath holding dive. This was first described by S. Miles as “latent hypoxia”, shallow water blackout is the term he ascribed to unexplained loss of consciousness in divers using closed-circuit oxygen breathing apparatus at […]

Carbon Monoxide Poisoning

Carbon monoxide poisoning is a rare cause of problems when diving, it does occur when there is contaminated air in recreational diving tanks. CO poisoning is the leading cause of poisoning deaths in the U.S.(about 8600 deaths per year) and is easily missed unless health care providers are especially vigilant. The most commonly observed result […]

Nitrox Diving

Several agencies have begun training recreational divers with oxygen enriched compressed air (EAN). Recreational nitrox diving has in common with traditional compressed air diving the use of nearly all the same equipment and the use of only one gas mix per tank per dive. Advantages Advantages accrue for the user of nitrox in that he/she […]

CO2 Acclimatization

ACCLIMATIZATION YOU DON’T WANT – CARBON DIOXIDE Jolie Bookspan, Ph.D.University of Pennsylvania, Philadelphia, PAand(The Rev.) Edward H. Lanphier, M.D.,University of Wisconsin-Madison, Madison, WI In a US Navy experimental facility, testing for new decompression schedules was underway using nitrox mixtures with a higher concentration of oxygen than the 21 percent in air. The Navy investigators first […]

CO2 Retention in Scuba Diving

CO2 retention with it’s attendant dangers of death from convulsions and hypoxia (low oxygen level) is primarily of concern to the scuba diver due to “skip breathing”. Other sources of CO2 retention are breath-hold diving, breathing in a sealed environment, faulty regulator, exercise at extreme depth and using contaminated air. Symptoms include rapid respiration in […]

Air Travel, Oxygen and the Diver

There is a recurring question that arises concerning the use of oxygen in divers returning by air after having had treatment for a decompression accident. Dr. David DuBois has written asking about the appropriate management of the returning diver continuing to need oxygen after maximum recompression treatment but with residual symptoms. He asks, “Is there […]

Nitrogen Narcosis

What is it? Nitrogen narcosis is an effect on the brain of gaseous nitrogen that occurs to divers who go below 100 FSW, due to the laws of partial pressures. Nitrogen is an inert gas existing in largest quantity in the atmosphere, 79% in air. It is inert, meaning that it does not take part […]

Partial Pressure Physics in Diving

Partial-pressure effects: The partial pressure of a gas is determined by the concentration of the gas and the ambient pressure, eg, the concentration of O2 in air is about 21%, and the partial pressure of O2 in air at surface (1 atm abs) is about 0.21 atm. The concentration of O2 in air remains the […]

Oxygen Toxicity

The effects of oxygen are increased at depth so that the maximum PO2 in diving is 1.6 ATA, and this is achieved at 218 fsw breathing air, 132 fsw breathing 32% O2, and 20 fsw breathing 100% O2. This is due to the effects of Dalton’s Law which states that on descent, the partial pressure […]
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