title: Use of the laryngeal mask for closed circuit anesthesia.
abstract: We examined whether the laryngeal mask could be used effectively in 70 patients breathings spontaneously during closed-circuit anesthesia. After administration of oxygen 101.min-1, anesthesia was induced and the laryngeal mask inserted. After 6 min of denitrogenation (3.51.min-1 nitrous oxide and 1.51.min-1 oxygen), the fresh-gas flow was decreased to the minimum required to maintain refilling of a ventilator bellows (Carden Ventmasta); nitrous oxide was turned off. A vaporiser outside the breathing system was set either by observing an end-tidal agent monitor or at 3-5 times greater than the required end-tidal concentration. The total fresh gas flow, hemodynamics and respiratory variables were monitored. Several types of operations were performed and lasted 9-126 min (mean 37 min). The average total fresh gas flow during the closed circuit period was 340 ml.min-1 (range 200-500 ml.min-1). Blood pressure, heart rate and respiration were stable throughout anesthesia and there were no major side effects attributable to the technique. We believe that closed-circuit anesthesia in patients breathing spontaneously through the laryngeal mask, as described here, can be used safely, conveniently and effectively. This technique is suitable for surgical operations of short duration.
authors.affiliation: University of Wales College of Medicine, Heath Park, Cardiff, United Kingdom.
authors.forename: M R
authors.initials: MR
authors.lastname: Stacey
authors.forename: S
authors.initials: S
authors.lastname: Morris
authors.forename: T
authors.initials: T
authors.lastname: Asai
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000764:Anesthesia, Closed-Circuit / Q000295:instrumentation* / Q000379:methods; D018685:Anesthetics, Inhalation; D004737:Enflurane; D005260:Female; D006801:Humans; D007530:Isoflurane; D017214:Laryngeal Masks; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic
chemical_list: D018685:Anesthetics, Inhalation; D004737:Enflurane; D007530:Isoflurane