title: Operation Everest III (Comex'97): altitude-induced decompression sickness during a hypobaric chamber experiment: necessity for circulating venous gas emboli monitoring for the investigators.
abstract: BACKGROUND
  Acute exposure to altitude changes increases the risk of decompression sickness (DCS). Altitude-induced DCS incidence is from 15 to 20% and > 30% above 8,000 m. A particular risk occurs for scientific investigators during hypobaric chamber experiments.
  
  
  OBJECTIVE
  In the present study, we assess whether the detection of nitrogen venous gas emboli (VGE) could help to screen the investigators at risk for altitude-induced DCS.
  
  
  METHODS
  During a 32-day hypobaric chamber experiment, we collected clinical episodes of DCS symptoms in the investigators, and performed detection of VGE using two-dimensional (2D) echocardiography and pulsed Doppler ultrasonography guided by 2D images, graded from 0 to 5.
  
  
  RESULTS
  Eight investigators made a total of 32 flights, including 8 flights above 8,000 m, with a 15.6% overall incidence of DCS symptoms and a 50% incidence above 8,000 m. VGE detections were systematically performed at or above 8,000 m (eight detections), and some detections were performed at 5,000 m, 6,000 m, and 7,000 m. VGE grades 3 and 4 were present in all but one subject with DCS symptoms and preceded the "bends" in all cases. VGE detection thus confirmed, in a more sensitive way compared to clinical examination, that our precautionary measures for DCS were not optimized.
  
  
  CONCLUSIONS
  VGE monitoring for investigators during hypobaric chamber experiments increased the sensitivity for the detection of subjects at risk for DCS.
authors.affiliation: Service de réanimation médico-chirurgicale, Center Hospitalier du pays d'Aix, Aix-en-Provence. France.
authors.forename: Florence
authors.initials: F
authors.lastname: Molenat
authors.forename: Alain
authors.initials: A
authors.lastname: Boussuges
mesh_terms: D000328:Adult; D000532:Altitude Sickness / Q000000981:diagnostic imaging*; D001274:Atmospheric Pressure; D003665:Decompression Sickness / Q000000981:diagnostic imaging*; D004452:Echocardiography; D004618:Embolism, Air / Q000000981:diagnostic imaging*; D006352:Heart Ventricles / Q000000981:diagnostic imaging; D006801:Humans; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic; D011655:Pulmonary Embolism / Q000000981:diagnostic imaging*; D011667:Pulmonary Veins / Q000000981:diagnostic imaging; D012307:Risk Factors; D018608:Ultrasonography, Doppler