Rapid Deflation of the Bronchial Cuff of the Double-Lumen Tube After Decreasing the Concentration of Inspired Nitrous Oxide

Deflationary phenomena of the endotracheal tube cuff may occur after inspired nitrous oxide (N2O) concentrations are reduced, but deflationary phenomena of the double-lumen tube (DLT) cuff have not been investigated. In this study, tracheal and bronchial cuffs of left-sided Mallinckrodt (Athlone, Ireland) DLTs were inflated with air, 40% N2O, or 67% N2O (Air, N40, or N67 groups, respectively) in 24 patients undergoing thoracic surgery; 40 min later, O2 was substituted for N2O in some of the patients in the N40 group (N40-c group). Intracuff gas volumes, N2O concentrations, and cuff compliance were also measured. Both tracheal and bronchial cuff pressures significantly increased in the Air group but decreased in the N67 group. Neither pressure significantly changed in the N40 group, but both decreased in the N40-c group after terminating N2O anesthesia; the time required for bronchial cuff pressures to decrease by half (12.0 ± 5.5 min) was less than that for tracheal cuff pressures (31.2 ± 11.0 min, P < 0.01). The volume change in the N40-c group was not significantly different between the tracheal and bronchial cuffs, but tracheal cuff compliance was significantly higher than bronchial compliance. Therefore, filling DLT cuffs with 40% N2O stabilizes cuff pressure during anesthesia with 67% N2O, but bronchial cuffs deflate more quickly than tracheal cuffs after cessation of N2O administration through smaller compliance.