Pressure controlled versus volume controlled ventilation with laryngeal mask airway

Study Objective: To quantify tire impact on peak airway pressure of pressure-controlled and volume-controlled ventilation during Laryngeal Mask Airway (TM) (LMA) use. Design: Prospective, crossover clinical study. Setting: University-affiliated hospital. Patients: 32 ASA physical status I and II patients undergoing general anesthesia with the LMA. Interventions: Patients were ventilated for three minutes both with pressure-con trolled and volume controlled ventilation, provided that tidal volume (V-T) and inspiratory time (It) were constant. Measurements and Main Results: The monitored parameters were electrocardiography, arterial blood pressure, pulse oximetry, capnography, neuromuscular transmission, airway pressure and flow, and concentration of ventilated vapors and gases. The actually delivered V-T was similar with both types of ventilation (volume-controlled = 0.67 +/- 0.13 lt, pressure-controlled = 0.67 +/- 0.14 lt; p = 0.688). Peak airway pressure was lower during pressure-controlled ventilation (14.6 +/- 3.5 cmH(2)O) than during volume-controlled ventilation (16 +/- 4 cmH(2)O) (p < 0.001). Furthermore, we noted that the higher the airway pressure with volume-con trolled ventilation, the greater was the reduction in airway pressure during pressure-controlled ventilation. Conclusions: Pressure-con trolled rather than volume-controlled ventilation can improve the effectiveness of mechanical ventilation inpatients with high airway pressure. (C) 2001 by Elsevier Science Inc.