Document Detail


Risk of decompression sickness during exposure to high cabin altitude after diving.
MedLine Citation:
PMID:  14620473     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
BACKGROUND: Postdive altitude exposure increases the risk of decompression sickness (DCS). Certain training and operational situations may require U.S. Special Operations Forces (SOF) personnel to conduct high altitude parachute operations after diving. Problematically, the minimum safe preflight surface intervals (PFSI) between diving and high altitude flying are not known. METHODS: There were 102 healthy, male volunteers (34 +/- 10 [mean +/- SD] yr of age, 84.5 +/- 13.8 kg weight, 26.2 +/- 4.2 kg x m(-2) BMI) who completed simulated 60 fsw (feet of seawater)/60 min air dives preceding simulated 3-h flights at 25,000 ft to study DCS risk as a function of PFSI. Subjects were dry and at rest throughout. Oxygen was breathed for 30 min before and during flight in accordance with SOF protocols. Subjects were monitored for clinical signs of DCS and for venous gas emboli (VGE) using precordial Doppler ultrasound. DCS incidence was compared with Chi-squared; VGE onset time and time to maximum grade with one-way ANOVA (significance at p < 0.05). RESULTS: Three cases of DCS occurred in 155 subject-exposures: 1/35 and 0/24 in 2 and 3 h flight-only controls, respectively; 0/23, 1/37, and 1/36 for 24, 18, and 12 h dive-PFSI-flight profiles, respectively. DCS risk did not differ between profiles (chi2 [4] = 1.33; crit = 9.49). VGE were observed in 19% of flights. Neither VGE onset time nor time to max grade differed between profiles (82 +/- 38 min [p = 0.88] and 100 +/- 40 min [p = 0.68], respectively). CONCLUSION: Increased DCS risk was not detected as a result of dry, resting 60 fsw/60 min air dives conducted 24-12 h before a resting, 3-h oxygen-breathing 25,000 ft flight (following 30 min oxygen prebreathe). The current SOF-prescribed minimum PFSI of 24 h may be unnecessarily conservative.
Authors:
Neal W Pollock; Michael J Natoli; Wayne A Gerth; Edward D Thalmann; Richard D Vann
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Publication Detail:
Type:  Case Reports; Clinical Trial; Comparative Study; Controlled Clinical Trial; Journal Article; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  Aviation, space, and environmental medicine     Volume:  74     ISSN:  0095-6562     ISO Abbreviation:  Aviat Space Environ Med     Publication Date:  2003 Nov 
Date Detail:
Created Date:  2003-11-17     Completed Date:  2004-03-23     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  7501714     Medline TA:  Aviat Space Environ Med     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1163-8     Citation Subset:  IM; S    
Affiliation:
Center for Hyperbaric Medicine and Environmental Physiology, Department of Anesthesiology, Duke University Medical Center, Durham, NC 27710, USA. neal.pollock@duke.edu
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MeSH Terms
Descriptor/Qualifier:
Adult
Altitude*
Decompression Sickness / etiology*
Diving / adverse effects*
Humans
Incidence
Male
Military Personnel
Risk Factors

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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