Self-inflating bag or Mapleson C breathing system for emergency pre-oxygenation?

BACKGROUND: A crossover study was performed in healthy volunteers to compare the efficacy of a self-inflating bag with the Mapleson C breathing system for pre-oxygenation. METHOD: 20 subjects breathed 100% oxygen for 3 min using each device, with a 30 min washout period. The end tidal oxygen concentration and subjective ease of breathing were compared. RESULTS: There was a statistically significant difference in performance between the two devices, with the Mapleson C providing higher end expiratory oxygen concentrations at 3 min. The mean (SD) end expiratory oxygen concentration was 74.2 (3.8)% for the self-inflating bag (95% CI 72.4% to 75.9%) and 86.2 (3.7)% for the Mapleson C system (95% CI 84.5 to 88.0); p<0.0001. The 95% CI of the difference between the mean values for end expiratory oxygen concentration at 3 min was 10.0% to 14.2%. There was also a statistically significant difference in the subjective ease of breathing, favouring the Mapleson C system. CONCLUSION: The Mapleson C breathing system is more effective and subjectively easier to breathe through than a self-inflating bag when used for pre-oxygenation. However, these benefits must be weighed against the increased level of skill required and possible complications when using a Mapleson C breathing system.