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Record 6 of 177339
Relationship of Exercise, Age, and Gender on Decompression Sickness and Venous Gas Emboli During 2-Hour Oxygen Prebreathe Prior to Hypobaric Exposure
Author and Affiliation:
Conkin, J.(Baylor Univ., United States)
Gernhardt, M. L.(NASA Johnson Space Center, Houston, TX United States)
Foster, P. P.(Baylor Univ., United States)
Pilmanis, A. A.(Armstrong Lab., San Antonio United States)
Butler, B. D.(Texas Univ., Galveston, TX United States)
Beltran, E.(Texas Univ., Galveston, TX United States)
Fife, C. E.(Texas Univ., Galveston, TX United States)
Vann, R. D.(Duke Univ., Medical Center, Durham, NC United States)
Gerth, W. A.(Duke Univ., Medical Center, Durham, NC United States)
Loftin, K. C.(Wyle Labs., Inc., Life Sciences, Systems and Services, United States) Show more authors
Abstract: We evaluated four 2-hour oxygen prebreathe protocols combining adynamia (non-walking) and 4 different amounts of exercise for potential use with extravehicular activity (EVA) on the International Space Station. Phase I: upper and lower body exercises using dual-cycle ergometry (75% VO2 max for 10 min). Phase 11: same ergometry plus 24 min of light exercise that simulated space suit preparations. Phase III: same 24 min of light exercise but no ergometry, and Phase IV: 56 min of light exercise without ergometry. After 80 min on 100% O2, the subjects breathed 26.5% O2 - 73.5% N2 for 30 min at 10.2 psi. All subjects performed a series of upper body exercises from a recumbent position for 4 hrs at 4.3 psi to simulate EVA work. Venous gas emboli (VGE) were monitored every 12 min using precordial Doppler ultrasound. The 39 female and 126 male exposures were analyzed for correlations between decompression sickness (DCS) or VGE, and risk variables. The duration and quantity of exercise during prebreathe inversely relates to DCS and VGE incidence. The type and distribution of the 19 cases of DCS were similar to historical cases. There was no correlation of age, gender, body mass index, or fitness level with greater incidence of DCS or all VGE. However there were more Grade IV VGE in males > 40 years (10 of 19) than in those =< 40 years (3 of 107), with p<0.01 from Fisher's Exact Chi square The latency time for VGE was longer (103 min +/- 56 SD, n = 15 versus 53 min +/- 31, n =13) when the ergometry occurred about 15 min into the prebreathe than when performed at the start of the prebreathe, but the order of the ergometry did not influence the overall DCS and VGE incidence. An increasing amount of exercise during prebreathes reduced the risk of DCS during subsequent exposures to 4.3 psi. Age, gender, or fitness level did not correlate with the incidence of DCS or VGE (combination of Grades I-IV). However males greater than 40 years had a higher incidence of Grade IV VGE.
Publication Date: Jan 01, 2000
Document ID:
(Acquired Nov 09, 2000)
Document Type: Preprint
Meeting Information: 18-22 Jun. 2000; Stockholm; Sweden
Meeting Sponsor: Undersea and Hyperbaric Medical Society
Financial Sponsor: NASA Johnson Space Center; Houston, TX United States
Organization Source: NASA Johnson Space Center; Houston, TX United States
Description: 1p; In English
Distribution Limits: Unclassified; Publicly available; Unlimited
Rights: No Copyright
Availability Source: Other Sources
Availability Notes: Abstract Only
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