title: Enriched Air Nitrox Breathing Reduces Venous Gas Bubbles after Simulated SCUBA Diving: A Double-Blind Cross-Over Randomized Trial.
abstract: To test the hypothesis whether enriched air nitrox (EAN) breathing during simulated diving reduces decompression stress when compared to compressed air breathing as assessed by intravascular bubble formation after decompression.
  
  
  
  Human volunteers underwent a first simulated dive breathing compressed air to include subjects prone to post-decompression venous gas bubbling. Twelve subjects prone to bubbling underwent a double-blind, randomized, cross-over trial including one simulated dive breathing compressed air, and one dive breathing EAN (36% O2) in a hyperbaric chamber, with identical diving profiles (28 msw for 55 minutes). Intravascular bubble formation was assessed after decompression using pulmonary artery pulsed Doppler.
  
  
  
  Twelve subjects showing high bubble production were included for the cross-over trial, and all completed the experimental protocol. In the randomized protocol, EAN significantly reduced the bubble score at all time points (cumulative bubble scores: 1 [0-3.5] vs. 8 [4.5-10]; P < 0.001). Three decompression incidents, all presenting as cutaneous itching, occurred in the air versus zero in the EAN group (P = 0.217). Weak correlations were observed between bubble scores and age or body mass index, respectively.
  
  
  
  EAN breathing markedly reduces venous gas bubble emboli after decompression in volunteers selected for susceptibility for intravascular bubble formation. When using similar diving profiles and avoiding oxygen toxicity limits, EAN increases safety of diving as compared to compressed air breathing.
  
  
  
  ISRCTN 31681480.
authors.affiliation: Department of Medical Intensive Care and Hyperbaric Medicine, University Hospital, Angers, France.
authors.forename: Vincent
authors.initials: V
authors.lastname: Souday
authors.affiliation: Department of Medical Intensive Care and Hyperbaric Medicine, University Hospital, Angers, France.|INSERM U1083, CNRS UMR 6214, University Hospital, Angers, France.|Department of Anesthesiology. Institute for Cardiovascular Research, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: Nick J
authors.initials: NJ
authors.lastname: Koning
authors.affiliation: Department of Medical Intensive Care and Hyperbaric Medicine, University Hospital, Angers, France.
authors.forename: Bruno
authors.initials: B
authors.lastname: Perez
authors.affiliation: Department of Medical Intensive Care and Hyperbaric Medicine, University Hospital, Angers, France.
authors.forename: Fabien
authors.initials: F
authors.lastname: Grelon
authors.affiliation: Department of Medical Intensive Care and Hyperbaric Medicine, University Hospital, Angers, France.
authors.forename: Alain
authors.initials: A
authors.lastname: Mercat
authors.affiliation: Department of Anesthesiology. Institute for Cardiovascular Research, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: Christa
authors.initials: C
authors.lastname: Boer
authors.affiliation: Interactions Cellulaires et Applications Thérapeutique and DRCI Data management, SFR du pôle Santé; University Hospital, Angers, France.
authors.forename: Valérie
authors.initials: V
authors.lastname: Seegers
authors.affiliation: Institut für Anästhesiologische Pathophysiologie und Verfahrensentwicklung, Universitätsklinikum Ulm, Ulm, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Radermacher
authors.affiliation: Department of Medical Intensive Care and Hyperbaric Medicine, University Hospital, Angers, France.|INSERM U1083, CNRS UMR 6214, University Hospital, Angers, France.
authors.forename: Pierre
authors.initials: P
authors.lastname: Asfar
mesh_terms: D000328:Adult; D018592:Cross-Over Studies; D003664:Decompression / Q000379:methods*; D003665:Decompression Sickness / Q000209:etiology / Q000473:pathology / Q000517:prevention & control*; D004242:Diving / Q000009:adverse effects*; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D018496:Hyperoxia / Q000209:etiology / Q000473:pathology / Q000517:prevention & control*; D008297:Male; D008875:Middle Aged; D009584:Nitrogen / Q000627:therapeutic use*; D010100:Oxygen / Q000627:therapeutic use*; D010101:Oxygen Consumption / Q000187:drug effects; D011446:Prospective Studies; D011651:Pulmonary Artery; D012123:Pulmonary Ventilation; D012119:Respiration / Q000187:drug effects; D018617:Ultrasonography, Doppler, Pulsed
chemical_list: C041364:nitrox; D009584:Nitrogen; D010100:Oxygen