• Per Cajander, Lennart Edmark, Rebecca Ahlstrand, Anders Magnuson, and Alex de Leon.
• From the Department of Anaesthesia and Intensive Care, Faculty of Medicine and Health Örebro University, Örebro (PC), Department of Anaesthesia and Intensive Care, Västmanland Hospital, Västerås (LE), Department of Anaesthesia and Intensive Care, Faculty of Medicine and Health (RA), Clinical Epidemiology and Biostatistics, Faculty of Medicine and Health (AM), and Department of Anaesthesia and Intensive Care, Sahlgrenska University Hospital, Faculty of Medicine and Health, Örebro University, Örebro, Sweden (AdL).
• Eur J Anaesthesiol. 2019 Sep 1; 36 (9): 625-632.

BackgroundFace mask ventilation (FMV) during induction of anaesthesia is associated with risk of gastric insufflation that may lead to gastric regurgitation and pulmonary aspiration. A continuous positive airway pressure (CPAP) has been shown to reduce gastric regurgitation. We therefore hypothesised that CPAP followed by FMV with positive end-expiratory pressure (PEEP) during induction of anaesthesia would reduce the risk of gastric insufflation.ObjectiveThe primary aim was to compare the incidence of gastric insufflation during FMV with a fixed PEEP level or zero PEEP (ZEEP) after anaesthesia induction. A secondary aim was to investigate the effects of FMV with or without PEEP on upper oesophageal sphincter (UES), oesophageal body and lower oesophageal sphincter (LES) pressures.DesignA randomised controlled trial.SettingSingle centre, Department of Anaesthesia and Intensive Care, Örebro University Hospital, Sweden.ParticipantsThirty healthy volunteers.InterventionsPre-oxygenation without or with CPAP 10 cmH2O, followed by pressure-controlled FMV with either ZEEP or PEEP 10 cmH2O after anaesthesia induction.Main Outcome MeasuresA combined impedance/manometry catheter was used to detect the presence of gas and to measure oesophageal pressures. The primary outcome measure was the cumulative incidence of gastric insufflation, defined as a sudden anterograde increase in impedance of more than 1 kΩ over the LES. Secondary outcome measures were UES, oesophageal body and LES pressures.ResultsThe cumulative incidence of gastric insufflation related to peak inspiratory pressure (PIP), was significantly higher in the PEEP group compared with the ZEEP group (log-rank test P < 0.01). When PIP reached 30 cmH2O, 13 out of 15 in the PEEP group compared with five out of 15 had shown gastric insufflation. There was a significant reduction of oesophageal sphincter pressures within groups comparing pre-oxygenation to after anaesthesia induction, but there were no significant differences in oesophageal sphincter pressures related to the level of PEEP.ConclusionContrary to the primary hypothesis, with increasing PIP the tested PEEP level did not protect against but facilitated gastric insufflation during FMV. This result suggests that PEEP should be used with caution after anaesthesia induction during FMV, whereas CPAP during pre-oxygenation seems to be safe.Trial RegistrationClinicalTrials.gov, identifier: NCT02238691.

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