The effect of head rotation on efficiency of face mask ventilation in anaesthetised apnoeic adults

BACKGROUND Upper airway obstruction occurs commonly after induction of general anaesthesia. It is the major cause of difficult mask ventilation. OBJECTIVES The aim of this study was to determine whether head rotation improves the efficiency of mask ventilation of anaesthetised apnoeic adults. DESIGN A randomised, crossover study. SETTING Single university teaching hospital. PATIENTS Forty patients, aged 18 to 75 years with a BMI 18.5 to 35.0 kg m−2 requiring general anaesthesia for elective surgery were recruited and randomised into two groups. INTERVENTIONS Once apnoeic after induction of general anaesthesia, face mask ventilation began with pressure controlled ventilation, at a peak inspiratory pressure of 15 cmH2O. Each patient was ventilated for three 1-min intervals with the head position alternated every minute: group A, mask ventilation was performed with a neutral head position for 1 min, followed by an axial head position rotated 45° to the right for 1 min and then returned to the neutral position for another 1 min. In group B, the sequence of head positioning was rotated → neutral → rotated. MAIN OUTCOME MEASURES Expiratory tidal volume, measured with a respiratory inductive plethysmograph. RESULTS Two patients were excluded due to protocol violation; thus, data from 38 patients were analysed. The mean expiratory tidal volume was significantly higher in the rotated head position than in the neutral position (612.6 vs. 544.0 ml: difference [95% confidence interval], 68.6 [46.8 to 90.4] ml, P < 0.0001). CONCLUSION Head rotation of 45° in anaesthetised apnoeic adults significantly increases the efficiency of mask ventilation compared with the neutral head position. Head rotation is an effective alternative to improve mask ventilation if airway obstruction is encountered. TRIAL REGISTRATION ClinicalTrials.gov identifier: NCT02755077.