Inspiratory Support Improves Preoxygenation in Healthy Subjects

The Efficacy and Tolerability of Different Levels of Inspiratory Support and PEEP During Preoxygenation. A Randomized Controlled Trial.

Preoxygenation optimizes oxygen content in the functional residual capacity (FRC). Adequate preoxygenation is defined by an expiratory oxygen fraction (FEO2) > 90%. Inspiratory support and positive end expiratory pressure (PEEP) can create a better reservoir, improve gas exchange and shorten the time needed for adequate preoxygenation. The goal of the study is to evaluate the efficacy and tolerability of different levels of inspiratory support and positive end expiratory pressure during preoxygenation in healthy subjects.

We conducted a double blind prospective randomized trial on 20 healthy volunteers. Each subject went through three modes of preoxygenation in random order: normal breathing (SP), breathing under inspiratory support 4 cmH2O/PEEP 4 cmH2O (PSM-4) and inspiratory support 6 cmH2O /PEEP 4 cmH2O (PSM-6). Each mode lasted for 3 min and parameters were recorded every 10 s. We evaluated subject's tolerance, leaks and easiness of each mode of preoxygenation according to a simplified (1 to 4) scale. Two-way ANOVA was used to compare FEO2 while simple ANOVA was used for time to reach FEO2=90%.

Inclusion Criteria:

• Healthy volunteers
• Aged between 20 to 40 years

Exclusion Criteria:

• Body mass index > 30
• Mustache, beard
• Claustrophobia