Influence of neuromuscular blockade on the airway leak pressure of the ProSeal® laryngeal mask airway

Background: The ProSeal (R) laryngeal mask airway (PLMA) is increasingly used for surgical procedures that might require the intraoperative use of neuromuscular blocking agents. The airway seal of the PLMA depends on the interplay of the surrounding soft tissue of the neck and the cuff of the mask. An intraoperative neuromuscular blockade could lead to a decrease of the airway leak pressure (P-leak) secondary to the relaxation of the muscles of the neck. With this study we tested the hypothesis that a neuromuscular blockade can result in a decreased Pluk of the PLMA. Methods: The P-leak of the PLMA was studied in 73 female patients under total intravenous anaesthesia with propofol (0,1-0,15 mgkg(-1) min(-1)) and remifentanil (0,1 - 0,3 tgkg(-1) min(-1)) before and after a complete neuromuscular blockade produced by intravenous injection of 0.6mgkg(-1) Rocuronium. Results: The P-leak decreased by more than 10% of the baseline Pleak in 8 out of 73 patients (11 %); however, in the entire study population there was no significant difference between the mean baseline P-leak (28,5 +/- 7,3 cm H2O) and the mean P-leak after complete neuromuscular blockade (29,1 +/- 7,0 cm H2O); (p = 0,128). Conclusion: No general correlation between application of a neuromuscular blocking agent and a decrease of the mean Pleak was found. However, the decrease of the Pleak by more than 10% in 11 % of the patients shows that in certain patients the application of neuromuscular blocking agents can result in a decreased Pluk of the PLMA and indicates the necessity to control the Pleak of the PLMA under complete muscle paralysis preoperatively when neuromuscular blocking agents are used.