Here is an interesting story that will keep you on edge.

When Don Shirley and Dave Shaw discovered the corpse of a diver, missing for 10 years, in the depths of a South African cave, they knew they had to bring it back - even if it meant returning to the ‘dead zone’ 270m down, where few divers have ever ventured.

http://tinyurl.com/2f3k4b

If you didn’t have decompression sickness and entered a recompression chamber for treatment or demonstration purposes, would there be any medical problems due to hyperbaric treatment when it was not needed?
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. “Older divers remember the ‘oxygen toxicity’ test dives - in days bygone there was the periodic oxygen tolerance test. It was finally decided that the test results were good for the day you took the test without much predictive value. (Glen Egstrom, PhD). Dry dives can be fun if you are in a group with a good sense of humor”.
The London Diving Chamber  < http://www.londondivingchamber.co.uk/ >  has a website that appears to be promoting a taste of Nitrogen Narcosis in the dry without risk of drowning or DCI. “It is not a bad idea to demonstrate a chamber to a trainee diver; this may both reassure but at the same time endorse the need to avoid an unscheduled visit - at a later date!”  (Dr. Nick McIver).
“Dry dives mimic some of the effects of diving, such as N2 narcosis and the increase in gas density. Indeed, much of what we know about diving physiology comes from experiments in dry chambers. However, neither equipment not humans behave exactly the same in the water as in the dry”. (Richard Moon, MD).
Captain Dick Carson, USN (Ret) (PADI Instr) recounts the following about ‘dry dives’. “Being a frequent diver at Stoney Cove near Birmingham in England, I was often amazed as the dive store there used their mini-chamber to assemble semi-dry suits. The near 1-inch thick neoprene suit was compressed while taking the store clerk “down” to the point the “Whites Valve” could be installed on the suit at the location specified by the buyer. I did not time the “dive” but it seemed a bounce dive at the time. Another use for a chamber, and risks discounted.” The USN practiced similar events for wannabe pilots up to the mid 90’s as I  recall to determine if the student was “susceptible to the bends.”
Dr. Ed Kay relates that, “We still do (more conservative) dry chamber runs for scuba clubs and others interested in commercial diving at the Divers Institute (DIT).”
Dr. Allen Dekelboum describes his experience doing a dry dive with his course at NOAA. ” We dove 200 feet on air and then on helium. For the air dive, we were all extremely narced, but we were told we had a great time. No one got bent, but I did have a very slight case of niggles on the helium dive, all disappearing very quickly on 100% O2 .”
Other comments include: “It circumnavigates the actual causes of diving deaths, and so it probably does little harm”. (Carl Edmonds, MD). “A clever way to support running a chamber. Trying to experience narcosis in a relatively safe environment isn’t totally a bad idea.” (Ed Golembe, MD)

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.
In a 10-year study of 1,505 patients who received 52,758 2-hour HBO treatments at 2.4 ata once or twice daily (The maximum treatment protocol used for problem wounds around the world), the following side effects were noted:
Inability to equalize middle ear pressure 0.37%
Paranasal sinus blocks 0.09%
Confinement anxiety 0.05%
Oxygen convulsions 0.009% (all ceased after removing hood/masks)
Pulmonary oxygen toxicity 0.00%
Permanent ocular refractive changes 0.00%
Some of the contraindications for hyperbaric oxygenation are listed here. These could also apply to dry diving - but in each instance the person would probably not be certified as ‘fit to dive’ anyway.
1. Asthma - Small airway hyper-reactivity may result in air trapping and pulmonary barotrauma on ascent. A decision to treat such patients should not be undertaken lightly, particularly in light of evidence that the administration of some bronchodilators may increase the incidence of cerebral arterial gas embolism through pulmonary shunts from vasodilation. .
2. Congenital spherocytosis - Such patients have fragile red cells and treatment may result in massive hemolysis
3. Cisplatinum - There is some evidence that this drug retards wound healing when combined with HBO.
4. Disulphiram (Antabuse) - There is evidence to suggest that this drug blocks the production of suproxide dismutase and this may severely effect the body’s defenses against oxygen free radicals. Experimental evidence suggest that a single exposure to HBO is safe but that subsequent treatments may be unwise. Whether or not this would apply to air diving is unknown.
5. Doxorubicin - (Adriamycin). This chemotherapeutic agent becomes increasingly toxic under pressure and animal studies suggest at least a one week break between last dose and first treatment in the chamber.
6. Emphysema with CO2 retention - Caution should be exercised in giving high pressures + concentrations of oxygen to patients who may be existing on the hypoxic drive to ventilation. Such patients may become apneic in the chamber and require IPPV (intermittent positive pressure ventilation). In addition, gas trapping and subsequent lung rupture are associated with bullous disease.
7. High Fevers - High fevers (>38.5degC) tend to lower the seizure threshold due to O2 toxicity and may result in delaying of relatively routine therapy. If patients are to be treated then attempt should be made to lower their core temperature with antipyretics and physical measures. Whether or not this would apply to air diving is unknown.
8. History of middle ear surgery or disorders - These patients may be unable to clear their ears, or risk further injury with vigorous attempts to do so. An ENT consult for possible placement of tubes is usually wise. The risk for a dry dive would not be worth the benefit.
9. History of seizures - HBO therapy may lower the seizure threshold and some workers advocate increasing the baseline medication for such patients. Whether or not this would apply to air diving is unknown.
10. Optic Neuritis - There have been reports in patients with a history of optic neuritis of failing sight and even blindness after HBO therapy. This complaint would seem to be extremely rare but of tragic consequence. Whether or not this would apply to air diving is unknown.
11. Pneumothorax - A pocket of trapped gas in the pleura will decrease in volume on compression and re-expand on surfacing during a cycle of HBO therapy. During oxygen breathing at depth nitrogen will be absorbed from the space and replaced with oxygen. These fluxes of gases and absolute changes in volume may result in further lung damage and or arterial gas embolization. If there is a communication between lung and pneumothorax with a tension component, then a potentially dangerous situation exists as the patient is brought to the surface. As Boyle’s Law predicts, a 1.8 litre pneumothorax at 20 msw is potentially a 6 litre pneumothorax at sea level - certainly a life threatening situation. For this reason it is mandatory to place a chest tube to relieve a pneumothorax before contemplating HBO therapy. Particular care must be taken with patients who give a history of chest trauma or thoracic surgery.  Whether or not this would apply to air diving is unknown.
12. Pregnancy - The fears that either retrolental fibroplasia or closure of the ductuc arteriosus may result in the fetus whose mother undergoes HBO appear to be groundless from considerable Russian experience. However, HHI continues to exercise caution in limiting treatment of pregnant women to emergency situations.
13. Upper Respiratory Tract Infections - These are relative contra-indications due to the difficulty such patients may have in clearing their ears and sinuses. Elective treatment may be best postponed for a few days in such cases.
14. Viral Infections - Many workers in the past have expressed concern that viral infections may be considerably worsened after HBO. There have been no studies to give convincing evidence of this and no reported activation of herpetic lesions associated with HBO.
For more information, go to: www.scuba-doc.com/hbocont.htm.

Ern Campbell, MD
scubadoc Diving Medicine
http://scuba-doc.com/

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In a question on our Scuba Clinic Forum, there is a question about guidelines for the management of the accumulation of contaminants in wetsuits over time. There follows several answers concerning the washing and care of wet suits and basically stating that there needs to be studies to determine the correct way to rid wet suits of contaminants. You might want to vist the thread and post if you have any suggestions about maintaining your gear in polluted water and beaches.

The answer is that basically wet suits cannot be adequately cleaned after contamination.
Here is a great letter from Sean Sheldrake the Deputy Dive Safety Officer, USEPA, Region 10. We have his permission to publish.
“Dear Dr. Campbell,
We here in the Region 10 dive unit very much enjoy your blog and read it with some regularity. We did read some disturbing posts recently regarding “contaminated water diving” with a wetsuit*, and what was more disturbing, the implication that the wetsuit could somehow be cleaned. Other than covering or neutralizing foul odors, removing salts, etc., wetsuits cannot be cleaned. The diver always has a level of dermal exposure using a wetsuit (and by implication ingestion due to the use of an “in the mouth” regulator), and to varying degrees the wetsuit forever carries the contaminants to which it has been exposed. NOAA and EPA have done studies in the 1980’s which well establish the fact that neoprene materials will become impregnated with contaminants, and should be considered contaminated to varying degrees after diving in polluted water. See the excerpt from the Traver study at the link below “Interim protocol for diving operations in contaminated water”:
http://yosemite.epa.gov/r10/oea.nsf/webpage/Dive+Team+Safety
The EPA dive safety manual section on polluted water may also be of interest. We continue to post what polluted water information resources we can to our website, and advocate that public safety and commercial divers should always wear a full face mask, drygloves, and a non-neoprene drysuit like the Viking. Some like Mr. Barsky suggest that hardhat, surface supplied diving is always the way to go for any level of pollution, but when I see commercial divers working for a “low bid” commercial dive contractor in polluted water wearing wetsuits and recreational regulator units, I think a middle ground
can be advocated which gives the diver a modicum of protection (significant decrease in dermal and ingestion pathway exposure) without spending $10k to outfit one diver in the water.
Thank you for your time.
Sean Sheldrake, Deputy Dive Safety Officer USEPA, Region 10 Environmental Cleanup Office
1200 Sixth Avenue Mailstop: ECL-110 Seattle WA 98101-1128 sheldrake.sean@epa.gov Phone:
206/553-1220 / Fax: 206/553-0124 or -0910 http://yosemite.epa.gov/r10/oea.nsf/webpage/dive+team
http://yosemite.epa.gov/r10/cleanup.nsf/sites/ptldharbor
”
More about diving in polluted water on our web site here: http://www.scuba-doc.com/polwater.html

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There is one simple action that you can take to possibly save the life of a loved one or a good friend! That is to learn how to get an unconscious or weakened, exhausted person back aboard a boat if they have fallen overboard or have had a swimming or scuba accident. This might seem to be a simple thing to do but it can be almost impossible if person is unconscious and you have no one else to help.

Even if you have had rescue courses where you discuss or practice removal from the water, the scenario is often very different from the private boat situation. An unconscious swimmer or diver is a completely dead weight and is unable to help in any way. If it is a diver, you must remember to remove as much of the gear as possible, not wasting time saving the gear. Inflation of the BC is helpful while the person is still in the water and can be helpful in getting a grasp on the unconscious diver. Often the ladder is of no help, either too high or too mobile. Ropes and lines are often spliced or in use with an anchor and are not readily available.  We present here some tips that might help you get a person into a boat so that a timely resuscitation can be performed.

If you are using an inflatable boat, it might seem easy just to pull the swimmer over the side. This just does not happen however, since the person’s legs tend to float up under the boat and can stop the lift dead in it’s tracks. If the boat is underway as in the process of rescuing a swimmer, the forward motion of the boat keeps the legs from catching and assists in rolling the person into the boat. If the boat is anchored, the best method is to face the person away from you or side on so that the legs won’t catch under the inflation tube. An alternative would be to pull the person alongside flat and lift and roll him into the boat.

Small rigid boats, 12-21 feet in length, can pose similar problems with the same suggestions operable. Legs get caught under the hard chine of the boat. This is not a problem with displacement vessels that have a nice curve under the boat, but which have other more difficult rescue problems unless specially equipped with dive or marlin platforms. Small boats may tip when two or more rescuers stand on one side: add to this the weight of the unconscious victim and we may have a problem with all persons in the water. Getting the victim in the boat over the stern, sitting down to keep the center of gravity low, lifting and rolling the victim over the side may work. Another method is to have a seat that can act as a lifting board (see-saw) over the gunwale or transom. The bottom line is that practice of these methods will find a system that works for you.

Larger vessels usually have higher sides but have better stability and usually a larger crew. These boats usually have a rescue system of some sort stowed aboard. Even these systems require practice and knowledge of the workings of the method, learned only by trials. Lifting stretchers, rigging systems using the boom or mast may be elegant but if not practiced or used often can take too long to set up, negating any benefit to the unconscious victim. Remember that it only takes four minutes of anoxia to cause brain damage.

Systems that work best are the netted ropes or canvas and netting with plastic segments to roll the victim into the boat. Larger boats with marlin boards or dive platforms tend to have fewer problems. Larger crews also provide brute strength, good for simply pulling a diver aboard. Even this can be impossible if there is not a person in the water lifting the arms up for grasping by the onboard crew. Even so it becomes much easier if the victim is moving in the direction of the rescuer by bouncing and pulling the victim higher with each bounce.

The take home message is simple: plan and above all practice the rescue beforehand

Beer While Diving? There have been recent assertions in scuba magazines, chat rooms and scuba forums that it’s OK to drink beer between dives during a surface interval. 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! 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. Blood Alcohol Concentration (BAC) 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 reached 0.0%. This means that the risk for injury of a hung-over 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. Alcohol Impairment 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 attention 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. Alcohol is a diuretic In addition to these dangers is the definite danger of alcohol-produced dehydration. Dehydration is considered to be one of the prime causes of decompression illness. Alcohol in any form has a direct effect on the kidneys, causing an obligatory loss of body fluids. If your drinking buddy is an intelligent diver, surely he will understand that this is not preaching - a cool beer is appreciated by the author - but by drinking and diving he can turn a safe sport into a nightmare for himself and his family. I’m sure that when he considers that he is also endangering his buddy that he will think twice before drinking alcohol before and while diving. 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. As Lieber has stated in his study on the effects of small amounts of alcohol, “alcohol can never make you do a thing better, it can only make you less ashamed of your mistakes.” 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 headfirst 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.

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Fabio Spigno^a, Massimo De Lucchi^b, Luca Migliazzi^a and Leonardo Cocito^{c, ,
a}Department of Occupational Medicine, University of Genova, Genova, Italy
^bUnit of Hyperbaric Therapy, San Martino Hospital, Genova, Italy
^cDepartment of Neurosciences, Ophthalmology and Genetics, University of Genova, Genova, Italy
Received 5 June 2007;  revised 24 August 2007;  accepted 27 August 2007.  Available online 24 October 2007.

There is an article in the Los Angeles Daily News describing a program for training prisoners in diving skills, including diving medicine.

For the entire article see this link:
Prisoners endure diver’s training program