Randomised comparison of the laryngeal tube and the laryngeal mask during anaesthesia with controlled ventilation

The laryngeal tube has been evaluated for brief periods of anaesthesia only [1, 2]. The device has been modified since its introduction. This evaluation compares the new laryngeal tube with the classic laryngeal mask airway throughout anaesthesia with controlled ventilation. Seventy-two ASA 1-2 patients were studied. Anaesthesia was with total intravenous anaesthesia using propofol, fentanyl and rocuronium. Patients were randomised to airway management with the laryngeal tube or laryngeal mask airway. Manufacturer's instructions were followed for all aspects of airway use. Insertion was successful with 36/36 laryngeal mask airways and 35/36 laryngeal tubes. Insertion of the laryngeal tube required more manipulations than the laryngeal mask airway (p < 0.05), although the time taken was identical. Complications were infrequent. Airway seal pressure was 28 cm H2O with the laryngeal tube and 20 cm H2O with the laryngeal mask airway (p < 0.05). The peak airway pressure to deliver 7 ml.kg was 3 cm H2O higher with the laryngeal tube than the laryngeal mask airway (p < 0.05). Ventilation was perfect with the laryngeal tube in 32/35 cases and with the laryngeal mask airway in 29/32 (p > 0.05). Gas leak around the laryngeal mask airway occurred more frequently with the laryngeal mask airway than the laryngeal tube. There were more manipulations required in the laryngeal tube group during maintenance of anaesthesia. The airways were equally well tolerated during emergence and recovery and complications were equal in each group. Postoperative sequelae were similar in incidence, severity and number of patients affected with either device. The laryngeal tube allows an improved airway seal for lung ventilation compared to the laryngeal mask airway. However it requires a greater number of airway manipulations for insertion. Ventilation via the laryngeal tube requires a higher peak pressure than with the laryngeal mask airway.