Dextromethorphan premedication in the alleviation of cough during flexible bronchoscopy in adults: A randomized double-blind placebo-controlled trial

Cough is invariably encountered during flexible bronchoscopy despite sedation and topical anaesthetics. The ideal cough suppressant during flexible bronchoscopy is not known. We assessed the role of dextromethorphan premedication in relieving the cough during flexible bronchoscopy in adults.

In this single-centre study, we randomized patients aged ≥18 years to receive dextromethorphan syrup 30 ml (90 mg) or an equal volume of placebo 1 h before the procedure. Patients rated their cough severity and discomfort on a visual analogue scale at the end of the procedure. Bronchoscopists also rated cough severity at the end of the procedure.

Out of 112 patients screened, 94 patients (median (interquartile range [IQR]) age 51 (36.25-60.75) years, male: female 2.13:1) were randomized to either the dextromethorphan (n = 47) or placebo (n = 47) groups. The patients-rated median (IQR) cough scores at the end of the procedure were 15 (10-23) mm in dextromethorphan versus 20 (12-45.5) mm in placebo groups (p = 0.03). Patients-rated median cough scores at 1 h (5 mm vs. 6 mm, p = 0.21), discomfort scores (12.5 mm vs. 12.5 mm, p = 0.49), and midazolam and lignocaine usage were similar between the two groups. The bronchoscopist-rated median cough score was non-significantly lower in the intervention compared to the placebo (26 mm vs. 35 mm, p = 0.09) groups.

Dextromethorphan premedication 1 h before flexible bronchoscopy may have an additive effect on cough suppression under conscious sedation and topical lignocaine. Further trials are needed to reiterate our findings with certainty.