title: Techniques of preoxygenation in patients with ineffective face mask seal.
abstract: BACKGROUND
  Ineffective face mask seal is the most common cause for suboptimal pre-oxygenation. Room air entrainment can be more with vital capacity (VC) breaths when the mask is not a tight fit.
  
  
  OBJECTIVE
  This study was designed to compare 5 min tidal volume (TV) breathing and eight VC breaths in patients with ineffective face mask seal.
  
  
  METHODS
  Twenty eight ASA I adults with ineffective face mask seal were randomized to breathe 100% oxygen at normal TV for 5 min (Group TV) and eight VC breaths (Group VC) in a cross over manner through circle system at 10 L/min. End tidal oxygen concentration (EtO2) and arterial blood gas analysis was performed to evaluate oxygenation with each technique.
  Data were analysed using SPSS statistical software, version 16. Friedman's two-way analysis of variance by ranks was used for non-parametric data.
  
  
  RESULTS
  Significant increase in EtO2 (median 90) and PaO2 (228.85) was seen in group TV when compared to group VC (EtO2 median 85, PaO2 147.65), P<0.05. Mean total ventilation volume in 1 min in group VC was 9.4±3.3 L/min and more than fresh gas flow (10 L/min) in seven patients. In group TV, the fresh gas flow (50 L/5 min) was sufficient at normal TV (mean total ventilation in 5 min 36.7±6.3 L/min).
  
  
  CONCLUSIONS
  TV breathing for 5 min provides better pre-oxygenation in patients with ineffective mask seal with fresh gas flow of 10 L/min delivered through a circle system.
authors.affiliation: Department of Anaesthesiology and Critical Care, Jawaharlal Institute of Postgraduate Medical Education and Research Centre, Pondicherry, India.
authors.forename: Pankaj
authors.initials: P
authors.lastname: Kundra
authors.forename: Shirley
authors.initials: S
authors.lastname: Stephen
authors.forename: Stalin
authors.initials: S
authors.lastname: Vinayagam
keywords: Face mask; pre-oxygenation; tidal volume; vital capacity