title: Rapid deflation of the bronchial cuff of the double-lumen tube after decreasing the concentration of inspired nitrous oxide.
abstract: Deflationary phenomena of the endotracheal tube cuff may occur after inspired nitrous oxide (N(2)O) 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% N(2)O, or 67% N(2)O (Air, N40, or N67 groups, respectively) in 24 patients undergoing thoracic surgery; 40 min later, O(2) was substituted for N(2)O in some of the patients in the N40 group (N40-c group). Intracuff gas volumes, N(2)O 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 N(2)O 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% N(2)O stabilizes cuff pressure during anesthesia with 67% N(2)O, but bronchial cuffs deflate more quickly than tracheal cuffs after cessation of N(2)O administration through smaller compliance.
  
  
  CONCLUSIONS
  We demonstrated that after cessation of nitrous oxide (N(2)O) administration, bronchial N(2)O-filled cuffs of the double-lumen tube deflate more rapidly than tracheal cuffs. To avoid insufficient separation of the lungs by the bronchial cuff, a frequent check of the cuff pressure is recommended after the inspired N(2)O concentration is decreased.
authors.affiliation: Department of Anesthesiology, National Defense Medical College, Tokorozawa, Saitama 359-8513, Japan. karasawa@me.ndmc.ac.jp
authors.forename: Fujio
authors.initials: F
authors.lastname: Karasawa
authors.forename: Akira
authors.initials: A
authors.lastname: Takita
authors.forename: Isao
authors.initials: I
authors.lastname: Takamatsu
authors.forename: Tomohisa
authors.initials: T
authors.lastname: Mori
authors.forename: Takashi
authors.initials: T
authors.lastname: Oshima
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Kawatani
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000769:Anesthesia, Inhalation / Q000295:instrumentation* / Q000379:methods; D018685:Anesthetics, Inhalation; D001980:Bronchi / Q000502:physiology; D005260:Female; D006801:Humans; D007442:Intubation, Intratracheal / Q000295:instrumentation* / Q000379:methods; D008170:Lung Compliance / Q000502:physiology; D008297:Male; D008875:Middle Aged; D009609:Nitrous Oxide; D011312:Pressure; D014132:Trachea / Q000502:physiology
chemical_list: D018685:Anesthetics, Inhalation; D009609:Nitrous Oxide