[abstract] RISK IN SUBMARINE ESCAPE MINIMIZED BY RESCUE DECOMPRESSION: UW SHEEP MODEL OUTCOMES.

Rubicon Research Repository/Manakin Repository

[abstract] RISK IN SUBMARINE ESCAPE MINIMIZED BY RESCUE DECOMPRESSION: UW SHEEP MODEL OUTCOMES.

Show full item record


Title: [abstract] RISK IN SUBMARINE ESCAPE MINIMIZED BY RESCUE DECOMPRESSION: UW SHEEP MODEL OUTCOMES.
Author: Lehner, CE; Dueland, RT; Wilson, MA; Nordheim, EV; Vaicekavicius, L; Crump, PM; Gendron-Fitzpatrick, AP; Quigley, PD
Abstract: BACKGROUND: Personnel in a disabled submarine may be exposed to increased pressure for 24 h or longer before they can evacuate to the surface. Direct ascent to the surface or "drop-out" can entail high mortality due to chokes or respiratory decompression sickness (RDCS) and CNS-DCS. A rescue submersible or bell used to evacuate submariners provides a slower rate of decompression that can reduce lethal DCS during rescue. The UW sheep model was used to evaluate decompression outcomes. METHODS: Thirty-six adult sheep experienced 24-h hyperbaric exposures of 60 fsw (2.81 atm abs) pressure followed by 3 rates of decompression on air: 2-min "drop-out" vs. 1-h and 4-h decompressions, with decompression stops proportional to U.S. Navy Treatment Table 7. Clinical signs were used to evaluate potentially-lethal DCS: CNS-DCS and RDCS. Fisher's exact test was used to evaluate survival, and logistic regression was used to predict probabilities of lethal DCS with 95percent confidence limits. RESULTS: Sheep decompressed from 60 fsw in 2 min resulted in 62.5percent (5/8) lethal outcomes; in 1 h in 36percent (5/14); and in 4 h in 0percent (0/14), with a significant dose-response (P = 0.0022, Fisher's exact test). Overall, CNS-DCS with a 17percent incidence (6/36) was less frequent than RDCS with a 69percent incidence (25/36). In 4-h decompression, non-lethal CNS-DCS and RDCS occurred in 0/14 vs. 6/14, respectively. Logistic regression of outcome vs. decompression time as sq rt (P less than 0.01) provided estimates of percentage lethal DCS +/- 95percent confidence limits: 2-min, 71percent (38-90percent); 30-min, 42percent (23-64percent); 60-min, 27percent (13-49percent); 90-min, 18percent (7-40percent); 120-min, 13percent (4-35percent); 180-min, 6.7percent (1.3-28percent); and 240-min decompression, 3.8percent (0.5-24percent). CONCLUSION: Emergency evacuation of personnel from a disabled submarine after a prolonged hyperbaric exposure can involve fatal DCS risk which can be mitigated by slower decompression on air in a rescue submersible. (Research was funded by the U.S. Navy.)
Description: Undersea and Hyperbaric Medical Society, Inc. (http://www.uhms.org )
URI: http://archive.rubicon-foundation.org/900
Date: 2001

Files in this item

Files Size Format View
abstract.txt 259bytes Text file View/Open

This item appears in the following Collection(s)

  • UHMS Meeting Abstracts
    This is a collection of the published abstracts from the Undersea and Hyperbaric Medical Society (UHMS) annual meetings.

Show full item record

Browse

My Account