Comparison of the endotracheal tube intracuff pressure with cylindrical and tapered cuffs during nitrous oxide exposure: a randomized single-blinded clinical study

Abstract

Background: Tracheal complications caused by excessive mucosal pressure from an inflated endotracheal tube are major concerns during anesthesia; hence, an intracuff pressure of 20–30 cmH2O is recommended as a clinically acceptable intracuff pressure. Diffusion of nitrous oxide (N2O) into the endotracheal tube cuff increases the intracuff pressure, which may also be influenced by the cuff shape. Therefore, we investigated whether the intracuff pressure of a tapered cuff was different from that of a cylindrical cuff in patients undergoing general anesthesia using 60% N2O. Methods: Twenty-six patients who underwent general anesthesia using 60% N2O in supine position were randomly allocated to the cylindrical cuff group (Group C) or tapered cuff group (Group T). The baseline intracuff pressure was set at 20 cmH2O, and measured every 10 minutes for 60 minutes. Results: The primary outcome was the intracuff pressure at 60 minutes after N2O exposure, which was 40 cmH2O in Group C (95% CI 36–44) and 40 cmH2O (95% CI 35–45) in Group T (P = 0.895). The lower confidence limit of the intracuff pressures in both groups exceeded 30 cmH2O at 60 minutes of N2O exposure, which is the upper limit for clinically acceptable intracuff pressure (20–30 cmH2O). Conclusions: There was no significant difference in the intracuff pressures between cylindrical and tapered cuffs. Continuous or frequent monitoring is recommended regardless of the duration of the 60% N2O exposure because the intracuff pressure can exceed 30 cmH2O within an hour.