Wednesday, October 12, 2005

Drinking beer and Diving? Not such a good idea!

Scuba divers are at increased risk of alcohol related injuries and fatalities. There is a definite increased decompression risk for a diver who drinks alcohol before, during and shortly after diving. This is due to the obligatory diuresis caused by the alcohol resulting in dehydration.

In addition, there are other cautionaries that should be recognized. These include the possibility of alcohol-induced hypoglycemia and loss of consciousness while diving, mental obtundation, cognition problems and the additive effect of nitrogen narcosis to the already narcotized brain.

Here is some information condensed from our web site , "Alcohol and Diving" at http://www.scuba-doc.com/alch.htm . Some divers insist on drinking beer before, during and after their dives. Is there any danger in drinking alcoholic beverages and diving? The short answer is that by drinking alcohol before and during diving trips a diver severely endangers not only himself but his buddy!

Research has shown that there is a definite reduction in the ability of the individual to process information, particularly in tasks that require undivided attention - for many hours after the blood alcohol level has returned to normal. This means that the risk for injury of a hungover diver is increased significantly, particularly if high BAC levels were reached during the drinking episode.

The AMA upper limit of the BAC for driving a vehicle in the US is 0.05%. Surely diving with any alcohol on board would be foolish, considering the alien environment (water) and the complex skills required to follow no deco procedures.

All of the following behavioral components required for safe diving are diminished when alcohol is on board or has been on board in the prior 24 hours:

Reaction time
Visual tracking performance
Concentrated attention
Ability to process information in divided tasks
Perception (Judgment)
The execution of psychomotor tasks.

The individual who has alcohol onboard may not feel impaired or even appear impaired to the observer but definitely is impaired and this is persistent for extended periods of time. The use of alcohol, even in moderate doses, clearly carries a self-destructive aspect of behavior and leads to higher probabilities for serious accidents.

If you or your drinking buddy are intelligent divers, surely you will understand that this is not preaching - a cool beer is highly appreciated by the author - but by drinking and diving one can turn a safe sport into a nightmare for himself and his family.

A study by Perrine, Mundt and Weiner found (scuba) diving performances significantly degraded at blood alcohol levels of 40 mg/dl (04%BAC). They also cite a clear increase in the risk of injury at this level which can be reached by a 180 lb. man who ingests two 12 oz. beers in 1 hour on an empty stomach. This very pertinent study once again points out that there is a diminished awareness of cues and reduced inhibitions at relatively low levels of blood alcohol. Their study used well trained divers who were being paid to do their best as their diving performances were being videotaped.

My friend, Dr. Glen Egstrom, PhD has stated the problem succinctly. He made personal review of over 150 studies on the effects of alcohol on performance has resulted in the following observations:

1. Ingestion of even small amounts of alcohol does not improve performance: to the contrary it degrades performance

2. While there are variables that can speed up or delay the onset of the effects of alcohol, they are minor issues which do not overcome the decrements to the central and peripheral nervous system.

3. Alcohol can be cleared from the blood at a predictable rate. Generally on the order of .015% BAC per hour. This does not necessarily mean that the decrements in performance have been completely eliminated in that time.

4. Alcohol is a depressant drug that slows certain body functions by depressing the entire central nervous system. Effects are noticeable after one drink.

5. The effects are mood elevation, mild euphoria, a sense of well being, slight dizziness and some impairment of judgment, self control, inhibitions and memory.

6. Increases in reaction time and decreases in coordination follow the dose/response curve quite well.

7. Alcohol is involved in 50% +/- of all accidents involving persons of drinking age.

8. The deleterious effects of alcohol on performance are consistently underestimated by persons who have been drinking alcohol.

9. Divided attention tasks are found to be affected by alcohol to a greater degree than those tasks with single focus of concentration, i.e. a task such as a head-first dive into shallow water, with many interrelated decisions necessary to a successful dive, will be impacted to a greater degree than lifting a heavy weight.

Here's a good corollary, as flying and diving are somewhat similar in the hazards encountered:
http://www.cami.jccbi.gov/AAM-400A/400alcohol.html

http://cgi.canoe.ca/HealthReference/arf_alcohol1.html

References:
--Alcohol use and aquatic activities--Massachusetts. (1990). Journal Of The American Medical Association -(Chicago), 264(1), 19-20.
--Fowler and Adams found that alcohol exacerbates the slowing of reaction time (RT) produced by inert gas narcosis. "Dissociation of the effects of alcohol and amphetamine on inert gas narcosis using reaction time and P300 latency." Aviat Space Environ Med 1993 Jun; 64(6):493-9
-- Michalodimitrakis E, et al.
Nitrogen narcosis and alcohol consumption--a scuba diving fatality.
J Forensic Sci. 1987 Jul;32(4):1095-7.
-- Fowler B, et al.
Effects of ethanol and amphetamine on inert gas narcosis in humans.
Undersea Biomed Res. 1986 Sep;13(3):345-54.
--. Monteiro MG, et al. Comparison between subjective feelings to alcohol and nitrogen narcosis: a pilot study. Monteiro et al, found in a pilot study in 1996 that ethanol and nitrogen may share the same mechanisms of action in the brain and that biological differences might account for interindividual variability of responses to both ethanol and nitrogen
Alcohol. 1996 Jan-Feb;13(1):75-8.
--Hamilton K, et al.
Nitrogen narcosis and ethyl alcohol increase the gain of the vestibular ocular reflex.
Undersea Biomed Res. 1989 Mar;16(2):129-37.