Isoflurane anesthesia does not add to the bronchodilating effect of a beta 2-adrenergic agonist after tracheal intubation.
This double-blind study investigates whether isoflurane/N2O anesthesia adds to the bronchodilating effect of the beta 2-adrenergic agonist, fenoterol, after an endotracheal tube (ETT)-induced increase in airway resistance. Forty-five patients with ASA physical status I-II were randomly assigned to two groups: fenoterol-treated patients (n = 23) were given three metered-dose inhaler puffs (600 micrograms) of fenoterol 10 min before induction of anesthesia and placebo-treated patients (n = 22) received three puffs of an aerosol containing no medication. Anesthesia was induced with thiopental and vecuronium intravenously. Respiratory system resistance (Rrs) was measured using a CP-100 pulmonary function monitor 5 min after endotracheal intubation. Inhalation anesthesia was then begun using 50% N2O in O2 with end-tidal 1.3% isoflurane. Rrs measurements were repeated at 5, 15, and 30 min after the initiation of inhalation anesthesia. Postintubation Rrs was significantly lower in the fenoterol-treated patients than in the placebo-treated patients. Rrs declined by a mean of 17.1% after 30 min of inhalation anesthesia in the placebo-treated patients but declined by only 1.4% in the fenoterol-treated patients (P < 0.05 for fenoterol provides protection versus placebo). Our results confirm that fenoterol provides protection against ETT-induced increase of airway resistance. However, isoflurane, while a potent bronchodilator, does not add to the effect of fenoterol.
Wu
R S
RS
Department of Anesthesiology, Chang Gung Memorial Hospital, Linkou, Taiwan, Republic of China.
Wu
K C
KC
Wong
T K
TK
Tsai
Y H
YH
Cheng
R K
RK
Tan
P P
PP
Bishop
M J
MJ
D000318:Adrenergic beta-Agonists / Q000008:administration & dosage / Q000627:therapeutic use*; D000328:Adult; D000336:Aerosols; D000403:Airway Resistance / Q000187:drug effects; D000769:Anesthesia, Inhalation; D018685:Anesthetics, Inhalation / Q000008:administration & dosage*; D001980:Bronchi / Q000187:drug effects*; D001993:Bronchodilator Agents / Q000008:administration & dosage / Q000627:therapeutic use*; D004311:Double-Blind Method; D004357:Drug Synergism; D005260:Female; D005280:Fenoterol / Q000008:administration & dosage / Q000627:therapeutic use*; D006801:Humans; D007442:Intubation, Intratracheal; D007530:Isoflurane / Q000008:administration & dosage*; D008297:Male; D009330:Nebulizers and Vaporizers; D009609:Nitrous Oxide / Q000008:administration & dosage; D010919:Placebos
D000318:Adrenergic beta-Agonists; D000336:Aerosols; D018685:Anesthetics, Inhalation; D001993:Bronchodilator Agents; D010919:Placebos; D005280:Fenoterol; D007530:Isoflurane; D009609:Nitrous Oxide