title: [Inspiratory support versus spontaneous breathing during preoxygenation in healthy subjects. A randomized, double blind, cross-over trial].
abstract: OBJECTIVE
  Applying an inspiratory support (AI) and a positive end expiratory pressure (PEP) could increase the effectiveness of the preoxygenation.
  
  
  METHODS
  This randomized double blinded controlled study compares the impact on the expiratory oxygen fraction (FEO(2)) of two levels of AI with PEP to a traditional preoxygenation.
  
  
  METHODS
  Twenty healthy volunteers were studied. The criteria of exclusion were a body mass index >30, the presence of beard or moustache and the claustrophobia. Each subject went through three modes of preoxygenation during 3 minutes each in a random order: 1-spontaneous ventilation (VS), 2-preoxygenation with AI with 4 cmH(2)O/PEP 4 cmH(2)O (AI-4/PEP-4), 3-preoxygenation with AI with 6 cmH(2)O/PEP 4 cmH(2)O (AI-6/PEP-4). Subject's tolerance and leaks were also noted.
  
  
  RESULTS
  The FEO(2) at the end of the 3 minutes of preoxygenation was higher (p<0,001) with AI-4/PEP-4 (94+/-3%) and AI-6/PEP-4 (94+/-4%) than with technique VS (89+/-6%). One hundred percent and 90% of the participants reached one FEO(2)=90% with AI-4/PEP-4 and AI-6/PEP-4 respectively vs 65% with VS (p=0.0013). The participants tolerated better the VS and the AI-4/PEP-4 than the AI-6/PEP-4. More leaks were noted with the AI-6/PEP-4 than with the VS and the AI-4/PEP-4.
  
  
  CONCLUSIONS
  This study shows applying AI plus PEP during preoxygenation improves its effectiveness in the healthy subjects. It also suggests that, in a population of healthy volunteers, combination AI-4/PEP-4 is preferable to AI-6/PEP-4 because so effective, but better tolerated.
authors.affiliation: Département d'anesthésie, hôpital Maisonneuve-Rosemont, centre hospitalier, université de Montréal, 5415, boulevard de l'Assomption, Montréal, QC, Canada, H1T 2M4. i.tanoubi@umontreal.ca
authors.forename: I
authors.initials: I
authors.lastname: Tanoubi
authors.forename: P
authors.initials: P
authors.lastname: Drolet
authors.forename: L P
authors.initials: LP
authors.lastname: Fortier
authors.forename: F
authors.initials: F
authors.lastname: Donati
mesh_terms: D000328:Adult; D000399:Air Pressure; D015992:Body Mass Index; D002245:Carbon Dioxide / Q000378:metabolism; D018592:Cross-Over Studies; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008297:Male; D010100:Oxygen / Q000097:blood; D010101:Oxygen Consumption / Q000502:physiology; D010102:Oxygen Inhalation Therapy / Q000009:adverse effects; D011175:Positive-Pressure Respiration; D012121:Respiration, Artificial / Q000009:adverse effects; D015656:Respiratory Mechanics; D055815:Young Adult
chemical_list: D002245:Carbon Dioxide; D010100:Oxygen