Randomized comparison of laryngeal tube with classic laryngeal mask airway for anaesthesia with controlled ventilation

Background. Only a prototype laryngeal tube has been compared with the classic LMA(dagger) for brief periods of anaesthesia. We compared the new laryngeal tube (which had several improvements in design) with the classic LMA. Methods. We randomly allocated 72 patients to receive either the laryngeal tube or an LMA, and compared adequacy of controlled ventilation during anaesthesia (good: clear airway without complications; fair; clear airway with complications or suboptimal airway; or failed), leak pressure and the incidence of postoperative complications. Results. Insertion was successful within 2 attempts in all 36 patients for the classic LMA and in 35 patients for the laryngeal tube. The mean leak pressure for the laryngeal tube (28 cm H2O) was significantly greater than that for the classic LMA (21 cm H2O) (P<0.001; 95% CI 3.6-10.0 cm H2O). Ventilation was good in 25 cases, fair in 11, and failed in no patients with the classic laryngeal mask airway; and good in 23, fair in 11 and failed in two for the laryngeal tube. There was no significant difference in adequacy of ventilation between the groups. The median peak airway pressure for the laryngeal tube (17.5 cm H2O) was greater than that for the classic LMA (16 cm H2O) (difference: 2 cm H2O; 95% CI 0-5 cm H2O). There was no significant difference in the incidence and severity of the postoperative complications between the two groups. Conclusion. The laryngeal tube was as effective as the classic LMA during anaesthesia with controlled ventilation. There were similar operative and postoperative complications.