Terbutaline inhalation suppresses fentanyl-induced coughing

Purpose: To study the suppressive effect of inhalation of a selective β₂-adrenergic bronchodilator terbutaline, and the effect of an intravenous anticholinergic, atropine, on fentanyl-induced coughing. Methods: We studied 131 ASA class I patients, aged 16-45 yr, scheduled for elective surgery, randomized into four groups. Fifteen minutes before bolus fentanyl (5 μg · kg^-1, iv), patients inhaled either normal saline (4 ml; Group 1, n = 30) or terbutaline (5 mg in 2 ml normal saline; Group 2, n = 34) via a jet nebulizer. After inhalation of normal saline, patients in Group 3 (n = 32) received sterile water iv instead of fentanyl. Patients in Group 4 (n = 35) were pretreated with atropine (0.01 mg · kg^-1, iv) 10 min before iv fentanyl bolus. The onset, frequency and intensity of cough were observed immediately by an anaesthetist blinded to the study. Results: The cough frequency was higher in Groups 1 (43%) and 4 (46%) than in Groups 2 (3%) and 3 (0%) (P < 0.05). The onset time and intensity of cough showed no difference among groups. No truncal rigidity was observed in patients receiving fentanyl bolus iv. The blood pressure, heart rate, and peripheral oxygen saturation did not change in Groups 1, 2, and 3, while patients in Group 4 showed an increase in heart rate (25.5 ± 15.2%). Conclusions: The inhalation of a selective β₂-adrenergic bronchodilator, terbutaline, effectively inhibited fentanyl-induced cough, whereas atropine, an antimuscarinic vagolytic, had no efficacy. Our results suggest that bronchoconstriction may underlie the mechanism on fentanyl-induced cough.