Decompression sickness: risk factors and the monoplace chamber--a case report.

Discussions regarding the use of monoplace chambers for the treatment of decompression sickness (DCS) have continued for some time. Recently the role of these chambers has been reviewed by Kindwall (12) and critiqued by Moon (13). Various principles and concerns presented in their articles are illustrated by this case presentation of type II (serious) DCS with pulmonary and neurologic manifestations. Closely timed recurrent altitude exposure is discussed as a risk factor for DCS. Also, a newly defined risk factor (menstrual phase) is considered relevant to this case. Finally, we recommend that arrangements be made early in the management of DCS cases for transfer to a chamber which can provide definitive therapy.

The risk of developing decompression sickness during air travel following altitude chamber flight.

Approximately 35,000 students are trained annually in United States Air Force (USAF) altitude chambers. Students who depart the training site via aircraft on the same day as their altitude chamber exposure may place themselves at increased risk for decompression sickness (DCS). Air travel as a passenger in the immediate post-chamber flight period is unrestricted by current USAF regulations. A retrospective study was conducted to assess the potential risk involved in such post-chamber flight travel. During the years 1982-87, there were 292 cases of DCS involving altitude chamber students which were subsequently treated with hyperbaric oxygen therapy. Only seven cases were found wherein the student was asymptomatic prior to air travel and subsequently developed DCS. Because the percentage of students who postpone travel is unknown, a precise relative risk could not be determined. Although the number of cases where sequential chamber and aircraft hypobaric exposures has initiated DCS is small, the potential for such occurrences remains a health concern.

Type II altitude decompression sickness (DCS): U.S. Air Force experience with 133 cases.

Type II altitude-related decompression sickness (DCS), due to its wide spectrum of symptoms, is often difficult to diagnose. This difficulty sometimes leads unnecessarily to the permanent grounding of an experienced aviator. So that this condition could be better understood, a total of 133 cases of Type II altitude DCS (on file at the United States Air Force Hyperbaric Medicine Division, School of Aerospace Medicine, Brooks AFB, TX) were reviewed. Most cases (94.7%) followed altitude chamber training. The most common manifestation was joint pain (43.6%), associated with headache (42.1%), visual disturbances (30.1%), and limb paresthesia (27.8%). The next most common symptoms were, in order of decreasing frequency: mental confusion (24.8%), limb numbness (16.5%), and extreme fatigue (10.5%). Spinal cord involvement, chokes, and unconsciousness were rare (6.9%, 6%, and 1.5%, respectively). Hyperbaric oxygen treatment produced fully successful results in 97.7% of the cases. Only 2.3% of the cases resulted in residual deficit; no deaths occurred. A thorough knowledge of the differential diagnosis and predisposing factors is essential to narrow the margins of error in the diagnosis and prevention of decompression sickness in the operational or training environment. A recommendation for favorable consideration of waiver action for those aviators who suffered Type II DCS is presented. These recommendations are based on a unique classification of the severity of symptoms.