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. Aims: 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 (EtO 2 ) and arterial blood gas analysis was performed to evaluate oxygenation with each technique. Statistical Analysis: 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 EtO 2 (median 90) and PaO 2 (228.85) was seen in group TV when compared to group VC (EtO 2 median 85, PaO 2 147.65), 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.

Keywords

• Face mask
• pre-oxygenation
• tidal volume
• vital capacity