Randomized crossover comparison of the ProSeal with the classic laryngeal mask airway in unparalysed anaesthetized patients

Background. The ProSeal is a wire-reinforced laryngeal mask airway with an additional drain tube that leads to the distal tip of the laryngeal cuff. The design should improve the seal with the larynx. Methods. The ProSeal and classic laryngeal mask airways were compared in 180 patients in a randomized crossover study. Patients were anaesthetized without neuromuscular blocking drugs. Results. The ProSeal took more time and more attempts to insert successfully than the classic laryngeal mask airway. Insertion was successful on the first attempt in 81% of cases with the ProSeal and 90% with the classic laryngeal mask airway. The ProSeal required more air to achieve an intracuff pressure of 60 cm H2O (6 ml more for size 4 and 12 ml more for size 5). Laryngeal seal pressure was better with the ProSeal than the classic laryngeal mask airway. Median seal pressure was 29 cm H2O with the ProSeal and 18 cm H2O with the classic laryngeal mask airway. Laryngeal seal pressure was greater than 20 cm H2O in 87% of patients with the ProSeal and 41% with the classic laryngeal mask airway. Laryngeal seal pressure was greater than 40 cm H2O in 21% of patients with the ProSeal and in none of the patients with the classic laryngeal mask. Once placed, the ProSeal remained a stable and effective airway. Gastric tube insertion through the drain tube was attempted in 147 cases and was successful in 135 (92%). Conclusion. The ProSeal is more difficult to insert than the classic laryngeal mask airway but allows positive pressure ventilation more reliably than the classic laryngeal mask airway.