Comparison of three modes of positive pressure mask ventilation during induction of anaesthesia: a prospective, randomized, crossover study

Abstract

Mask ventilation of apnoeic patients may be associated with alveolar hypoventilation, hyperventilation and gastric insufflation, which may be affected by the mode of ventilation during induction of anaesthesia. This study is to compare the effect of three modes of positive pressure mask ventilation during induction of anaesthesia regarding ventilatory variables and gastric insufflation. Ninety (90) patients, ASA I-II were included in this prospective, randomized, crossover study. Patients were divided into three groups of different sequence of modes of ventilation. Each patient was ventilated with pressure-controlled ventilation (PCV), manual-controlled ventilation (MCV), and volume-controlled ventilation (VCV) during the induction of anaesthesia. Respiratory and haemodynamic variables were monitored. Gastric insufflation was detected with a stethoscope applied to epigastric area. Haemodynamic variables showed no significant differences between the three modes of ventilation. PCV was associated with lower peak airway pressures (11.4 +/- 1.2 cmH2O) compared with MCV and VCV (14.3 +/- 1.7 and 13.3 +/- 1.5 cmH2O; respectively P < 0.0001). Inspiratory and expiratory tidal volumes showed no significant differences between the three modes. Gastric insufflation was detected in one patient (1.1%) in the PCV group compared to three patients (3.3%) in the MCV group and three patients (3.3%) in the VCV group. We concluded that in this model of apnoeic patients with an unprotected airway, PCV was associated with lower peak airway pressure which may provide additional patient safety.