title: Supplementation of standard pre-oxygenation with nasal prong oxygen or machine oxygen flush during a simulated leak scenario.
abstract: The presence of a facemask leak significantly reduces the effectiveness of pre-oxygenation and increases the risk of post-induction hypoxia. We randomly assigned 24 healthy volunteers to a six-period crossover trial with and without a simulated facemask leak. Pre-oxygenation was performed using a standard anaesthesia machine circuit supplemented either by nasal prong oxygen or by anaesthesia machine flush oxygen. Each intervention was completed with both 3-min tidal breathing and 8 deep breath techniques: end-tidal oxygen fraction was used as the measure of pre-oxygenation effectiveness. The presence of a stimulated mask leak significantly reduced the effectiveness of pre-oxygenation regardless of the breathing method used. With a simulated facemask leak introduced, the mean (SD) end-tidal oxygen fraction with the 3-min tidal breath technique was 74.7 (9.3)% compared with 57.5 (6.2%) for the 8 deep breath technique with 3-min tidal breathing and a leak. End-tidal oxygen fractions increased by 11.0% (95% CI 7.8-14.3%) (p < 0.0001) with the addition of nasal prong oxygenation and 16.8% (13.6-20.0%) (p < 0.0001) with machine oxygen flush compared with standard pre-oxygenation. When a leak is present, 3-min tidal breathing with either nasal prong or anaesthesia machine flush oxygenation is an effective pre-oxygenation method, and preferable to the 8 deep breath method.
authors.affiliation: King Edward Memorial Hospital, Western Australia, Australia; Sir Charles Gairdner Hospital, Nedlands, Western Australia, Australia.
authors.forename: T
authors.initials: T
authors.lastname: Russell
authors.forename: L
authors.initials: L
authors.lastname: Ng
authors.forename: E
authors.initials: E
authors.lastname: Nathan
authors.forename: E
authors.initials: E
authors.lastname: Debenham
mesh_terms: D000328:Adult; D000769:Anesthesia, Inhalation / Q000295:instrumentation* / Q000379:methods; D018592:Cross-Over Studies; D004868:Equipment Failure; D005260:Female; D006801:Humans; D008297:Male; D008397:Masks; D008875:Middle Aged; D010100:Oxygen / Q000008:administration & dosage*; D012119:Respiration
chemical_list: D010100:Oxygen