Randomized crossover comparison of the ProSeal™ laryngeal mask airway with the Laryngeal Tube® during anaesthesia with controlled ventilation

Background. The Laryngeal Tube (LT(R)) performs similarly to the classic laryngeal mask airway during controlled ventilation but with an improved airway seal. We compared the laryngeal tube with the ProSeal(TM) laryngeal mask airway (PLMA) throughout anaesthesia. Methods. Thirty-two patients were studied using a randomized cross-over design. The primary outcome measure was airway seal pressure. Secondary outcome measures included peak and plateau airway pressures, time to achieve an airway, ease of insertion, airway manipulations required to achieve a patent airway and grade of fibre-optic laryngoscopy. The proportion of patients in whom good, fair or failed ventilation was achieved was also calculated. Results. No significant difference was found in regard to seal pressure (PLMA, median 26.5 cm H2O, range 10-40; LT, median 24, range 6-40; P=0.7, 95% confidence interval of the difference 3.5 to -4.0). There were two failures of insertion or ventilation in the LT group and none in the PLMA group. The peak airway pressure with the PLMA was lower than with the LT but the difference was clinically unimportant (PLMA, mean 16.2 cm H2O, sd 3.52; LT, mean 17.9, sd 5.21; P=0.02, 95% confidence interval of the difference -3.1 to -0.28). The PLMA took significantly less time to insert than the LT (PLMA, median 18.5 s, interquartile range 14-26; LT, median 22, interquartile range 15-36.5; P<0.02, 95% confidence interval of the difference -21.5 to -1.0). The PLMA gave a significantly better view on fibre-optic laryngoscopy than the LT (P<0.001, 95% confidence interval of the difference in grade -2.0 to -1.0). In the 16 patients in whom the PLMA was used during maintenance of anaesthesia ventilation was good in 15, fair in none and failed in one. The equivalent figures for the LT were good in nine, fair in six and failed in one (P=0.009). There was no significant difference in the plateau airway pressure, ease of insertion of the devices, number of manipulations required to achieve or maintain an airway, or in overall complications. Conclusion. The two devices performed equally well in terms of seal pressure. The PLMA was quicker to insert. Efficacy of ventilation was significantly better with the PLMA than the LT. The PLMA allowed a significantly better view of the larynx with a fibre-optic laryngoscope, and may therefore be of more use in cases where visualization of the larynx is required.