Tracheal dilatation by halothane and enflurane in man

The effect of halothane and enflurane on tracheal tone were studied in 21 patients during the induction of anesthesia. Endotracheal tube cuff pressure was used to measure tracheal tone. Anesthesia, maintained by nitrous oxide 70% in oxygen, was supplimented with succinylcholine drip infusion to immobilize the patient. Ventilation was controlled by a Volume-preset ventilator. In the halothane group, the initial cuff pressure was 14.8 +/- 1.3 (mean +/- SE) cmH(2)O but 10 min after 0.15 mg/kg of pancuronium injection, it increased to 21.7 +/- 2.3 cmH(2)O (control). Ten min after inhalation of 0.75% of halothane, cuff pressure decreased to 14.7 +/- 2.3 cmH(2)O (34 +/- 11% decrease from the control value). In the enflurane group, the initial cuff pressure was 17.6 +/- 1.8 cmH(2)O and it increased to 21.0 +/- 1.7 cmH(2)O (control) 10 min after pancuronium injection. Ten min after 1.7% of enflurane inhalation, cuff pressure decreased to 17.1 +/- 2.3 cmH(2)O (23.9 +/- 6% decrease from the control value). Halothane and enflurane produced similar tracheal dilatation in healthy individuals.