The effect of head rotation on efficiency of face mask ventilation in anaesthetised apnoeic adults: A prospective, randomised, crossover study.

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 prospective 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[degrees] 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

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