Hypochondria, or hooked on O2?
There's an interesting case report from New Zealand in the June 2005 issue of the South Pacific Underwater Medicine Society (SPUMS) Journal. Here's the abstract:

A young man presented to hospital on 15 occasions over eight months. Five of these were with presumed decompression illness (DCI) and for four he received recompression therapy. Each time, he presented with joint pains and non-specific symptoms, but never had objective neurological signs of DCI. His other presentations were for a wide range of complaints and multiple specialties were involved in his management. These presentations followed a characteristic pattern, always at night and mostly after midnight, and in most instances he was discharged without specific treatment, although he received normobaric or hyperbaric oxygen on almost every occasion. His diving-related presentations were initially plausible but on the last occasion he used an alias and, when challenged, discharged himself. What was driving this young man? The psychiatric differential diagnosis is wide, or was he just hooked on oxygen?

"The psychiatric differential diagnosis is wide" is doc-speak for "gee, there are a BUNCH of things that could be wrong in this guy's head." Possibilities include DCI, hypochondriasis, Munchausen syndrome and factitious disorder.

His first visit for an ostensible diving injury was after a couple of dives within the no-stop limits of the DCIEM tables. On this occasion, he got three HBO treatments over 3 days. Six weeks later he showed up again and again got 3 rides. Ten weeks after that, he came in under an alias but was recognized by a staff member in the emergency department, at which point he was referred for psychiatric assessment.

Full reference:
Inglis, S. Hooked on oxygen ... hypochondriasis perhaps? SPUMS Journal 205; 35:89-91.

It's certainly not unusual to be treated for DCS only to find out that it wasn't really DCS at all (of course, the case described above is extreme). For example, of 104 people treated for decompression illness among the U.S. military community on Okinawa, 10 were reassigned another diagnosis in retrospect by the attending physician after treatment. There was one case each of musculo-skeletal injury, herniated disc, acute gastroenteritis, traumatic neuropathy, Crown of Thorns envenomation, hysterical malingering (this one had 8 fruitless treatment cycles before getting a psychiatric consultation), hyperventilation, inner ear injury, sinus barotrauma, and cerebral hemorrhage.

Arness, M. K. (1997). Scuba decompression illness and diving fatalities in an overseas military community. Aviation Space Environmental Medicine, 68(4): 325-33.

Yer tootsies are TOO warm
This case report was presented at the 2005 Annual Meeting of the Undersea and Hyperbaric Medical Society. An interesting cautionary tale for drysuit divers in cold climates:

Anderson GP
Oregon Medical Group, Eugene, Oregon
BACKGROUND: This is a case report of burns suffered by a diver when commercial hand warmers were used in the feet of a dry-suit while using EAN32 (Nitrox 32%). An UHMS literature search has no previous reference of this problem.
CASE REPORT: A forty-one year old female assistant instructor with 1300 logged dives dove in cold water off the coast of Vancouver Island in 2003. She was using a dry-suit and 32% Nitrox as breathing gas. During a surface interval, she used two commercial hand-warmer pouches to warm her hands and she then slipped them into her dry-suit feet to stay warm diving. The maximum depth on the next dive was 135 fsw at the base of a wreck. After only two minutes at 135fsw, she ascended to 90 fsw and her feet began hurting. Thinking it was due to a squeeze, she added more gas into her dry-suit, and her foot pain worsened. She aborted the dive. Second-degree burns on the arches of her feet were found.
RESULTS: Commercial hand-warmers oxidize iron powder to produce heat. At atmospheric pressure, 1ATA, the heat is not excessive. At depth, the partial pressure of Oxygen was 1.63ATA and increased the oxidation to cause the burns. An UHMS literature search failed to discover previous citations regarding this problem, although it is known that hyperbaric chamber fires have been caused by these products as ignition sources.
CONCLUSIONS: Commercial hand-warmers should not be used in dry-suits especially when hyperoxic breathing mixtures are used. Divers should be aware of this problem, which has no previous mention in the UHMS literature.

My comment:
The instructions on these hand warmers state not to apply directly to the skin for extended periods of time, not to use on parts of the body other than the hand, and that if used incorrectly higher temperatures may occur causing burns. Manufacturers also make these warmers specifically for feet -- these reach a lower temperature (around 95 degrees F rather than 140 degrees for the hand warmers). The foot warmer directions state they are intended for use inside a shoe or boot where oxygen is restricted, and they are not to be used with bare feet.

Here's some information on why you should never take one of these pocket warmers into a hyperbaric chamber.

There's also a different kind of hand warmer that doesn't work with oxidation. It's that reusable kind with a gel and a metal disk inside.
Here's an explanation of how they work.
RSA meeting abstract
A poster my colleagues and I did for presentation at the Annual Meeting of the Research Society on Alcoholism in June 2005 (full copy can be downloaded here)


Decompression sickness (DCS), a rare but serious illness, is caused by the formation and/or growth of nitrogen gas bubbles in the body following a reduction in ambient pressure. These bubbles may become lodged in tissue or block blood flow, causing pain, motor weakness, sensory deficit, and paralysis. DCS is the most common scuba diving injury requiring treatment.

Diver training and safety organizations suggest that the consumption of alcohol before or after diving increases the risk of DCS by contributing to dehydration and affecting peripheral blood flow, thereby altering the absorption and elimination of nitrogen. However, there is no empirical evidence that drinking increases DCS risk, and in the absence of available data about alcohol consumption in both injured and non-injured divers, an association of drinking to DCS risk cannot be established.

We can investigate the role of alcohol in DCS risk by comparing the presence of alcohol in DCS injuries vs. another kind of diving injury, arterial gas embolism (AGE). The differences in the etiology and pathology of DCS and AGE (DCS is caused by rapid off-gassing of nitrogen leading to nitrogen gas bubbles in blood and tissue, AGE is caused by air bubbles in arterial blood resulting from lung overinflation) suggests that the postulated mechanisms for alcohol-related DCS risk are not relevant to AGE. If alcohol use is more often present in DCS relative to AGE, a hypothesis of increased DCS risk with drinking would be supported.

Analyses were conducted on a database of diving injuries maintained by the Divers Alert Network. The database includes information from recreational divers who were treated for a diving injury at hyperbaric chambers in North America or the Caribbean. We analyzed 2822 cases (28% female, mean age 34.7) treated between 1989 and 1994, 2499 of whom were diagnosed with DCS and 323 with AGE. Logistic regression analysis showed that while known risk factors for AGE (rapid ascent, running out of air) and for DCS (deep diving, exceeding tabled limits for depth and time) discriminated between DCS and AGE diagnosis, alcohol consumption did not. These findings do not support the contention that alcohol is a risk factor for DCS.
UHMS meeting abstract
A poster my colleagues and I did for presentation at the Annual Meeting of the Undersea and Hyperbaric Medical Society in June 2005:

CHARACTERISTICS OF DIVERS TREATED FOR DECOMPRESSION SICKNESS AT VIRGINIA MASON MEDICAL CENTER. Dunford RG, Oras MJ, Leigh BC, Hampson NB. Center for Hyperbaric Medicine, Virginia Mason Medical Center, Seattle, Washington. Explosive Ordnance Disposal Mobile Unit Eleven, NAS Whidbey Island, Oak Harbor, WA. Alcohol and Drug Abuse Institute, University of Washington, Seattle, WA.

INTRODUCTION: The Center for Hyperbaric Medicine at Virginia Mason Medical Center treated its first diving accident patient in April 5, 1969, and through Nov 13, 2003 has treated 1129 cases of decompression illness. This study examines specific characteristics of these recreational divers treated for decompression sickness.

METHODS: Data were extracted from existing paper charts. Multivariate logistic regression was used to estimate the relationship of DCS diagnosis (mild vs. severe DCS) to predictor variables of gender, age, location of dive, delay to treatment, worst symptom and type of dress (wetsuit or drysuit). The diagnosis entered into the chart was also compared to that assigned during review (USN Diving Medical officer).

RESULTS: Among recreational divers treated for decompression sickness (n= 604), agreement between initial diagnosis and revised diagnosis was excellent, (Kappa=.88) in particular, after dropping cases (n= 50) where subsequent medical reviews found etiologies unrelated to diving. Female divers (OR=1.9, 95% CI = 1.1, 3.4) and divers who were diving outside of Washington State (OR= 2.4, 95% CI = 1.2, 5.0) were more likely to be diagnosed with severe DCS. Diver age, dress, and delay to treatment were not significantly related to diagnosis.

CONCLUSIONS: Female divers were diagnosed more severely even when severity of symptoms was controlled. We speculate that severe cases of DCS occurring outside of Washington are likely to be treated at or near the diving location and report to the VM Chamber for follow up while milder cases are more likely resolved on location.
Speaking of hyperbaric chambers ...
While I was Googling for something else entirely, I ran across the Timken Tank. This is a must-see:

Monster steel ball
Timken tank

Here's a little more information about Orval J. Cunningham:

Orval J. Cunningham, a professor of anesthesia at the University of Kansas in Kansas City, was the last of the great compressed air enthusiasts. He started out legitimately enough, noting that people with heart disease and certain other circulatory disorders did poorly when living at altitude, but improved on return to sea level. Taking this concept one step further, he felt that increased atmospheric pressure would be still more beneficial. During the flu epidemic of 1918, he placed a moribund young resident physician in a chamber which had been used for animal studies and by compressing him to two atmospheres was able to successfully oxygenate him during his hypoxic crisis. Having thus proved to himself that his concept was sound, he constructed an 88-foot long chamber, 10 feet in diameter, in Kansas City and began to treat a multitude of diseases, most of them without scientific rationale.

Mr. Timken of the Roller Bearing Company came under his care and apparently had a spontaneous recovery from a uremia while in Cunningham's chamber. In gratitude to Dr. Cunningham, Timkin built him the largest hyperbaric chamber ever constructed. It was steel sphere six stories high and 64 feet in diameter. This "steel ball hospital," located in Cleveland, Ohio, accommodated a smoking room on the top floor, plush carpeting, dining rooms and individual rooms. It could reach three atmospheres pressure.

Cunningham felt that some anaerobic organism "which could not be cultured" was responsible for a host of diseases including hypertension, uremia, diabetes and cancer and that compressed air therapy helped inhibit this organism. The AMA and the Cleveland Medical Society, failing to receive any scientific evidence for his rationale, finally forced him to close in 1930. Unfortunately, the steel ball hospital was broken up for scrap during World War II. It would have made a magnificent museum.

(from Yutsis & Dimant, Hyperbaric Oxygen Therapy, Townsend Letter #209, p. 68-70
New hyperbaric chamber to open
Virginia Mason's new hyperbaric chamber is set to open for business on June 27. Although the photograph in this article makes it look like an igloo more than anything else, it really looks more like, well, a big tube.

Whatever it looks like, the thing is absolutely huge: 46 feet long by 10 feet in diameter. Those divers unlucky enough to have been treated for decompression illness in the old chamber will be astonished at the roominess of this baby.

The new chamber is across the street from the old one, in the main hospital building. I haven't seen the finished space, but I was able to take a quick tour while it was under construction. Some photos here.