The effect of nitrous oxide on intracuff pressure of the size 2 ProSeal Laryngeal Mask Airway

Study Objective: To investigate intracuff pressure changes in the ProSeal Laryngeal Mask Airway (PLMA) during 50% nitrous oxide (N(2)O) anesthesia. Design: Prospective, randomized study. Setting: Operating room of a university-affiliated hospital. Patients: 40 ASA 1 and 2 children, aged 2 to 6 years, weighing 10-20 kg, undergoing elective inguinal hemiorrhaphy with general anesthesia. Interventions and Measurements: Patients were assigned to two groups (n = 20). Patients in Group A were anesthetized with 50% N(2)O in oxygen and sevoflurane, while patients in Group B were anesthetized with 50% air in oxygen and sevoflurane. PLMA cuffs were inflated with air. PLMA intracuff pressures starting from a baseline pressure of 30 mmHg were recorded using a pressure transducer for 30 minutes. The occurrence of postoperative throat discomfort was recorded. Main Results: In Group A, who inhaled 50% N(2)O for 30 minutes, intracuff pressures reached 86.7 +/- 10.4 mmHg, while in Group B, who inhaled 50% air for 30 minutes, intracuff pressures were 29.7 +/- 1.0 mmHg. The postoperative throat complication rate in Group A was 45%, which was significantly higher than in Group B (5%). Conclusion: PLMA intracuff pressure increased significantly during 50% N(2)O anesthesia. The children's postoperative throat complication rate also was increased. (C) 2011 Elsevier Inc. All rights reserved.