This study was designed to evaluate airway and intubating conditions without muscle relaxants after administration of
fentanyl and
propofol in 55 patients aged 20-60 years for elective surgery. Patients were randomly assigned to one of four groups to receive
fentanyl 0, 2, 3, or 4 micrograms.kg-1, respectively. Three minutes after the administration of
fentanyl,
propofol (2 mg.kg-1) was given for induction of
anesthesia. After the
loss of consciousness, laryngoscopy and tracheal intubation, supplemented with topical
anesthesia of
lidocaine (2 mg.kg-1), were attempted. In control group, without administration of
fentanyl, all patients were judged to provide poor intubating conditions. Increasing doses of
fentanyl reduced the incidences of movement and persistent coughing on laryngoscopy and intubation in a dose-related manner. However, visualization of the vocal cord was significantly. (P < 0.05) more likely to be impossible in patients in 4 micrograms.kg-1
fentanyl group (40%) compared with patients in 2 micrograms.kg-1
fentanyl group (7%). There were no significant differences among groups receiving
fentanyl with respect to vocal cord position. The vocal cords were closed in 26% of patients receiving
fentanyl and
propofol for intubation. Tracheal intubation without muscle relaxants is not recommended because of the potential unacceptable intubating conditions.