Does dextromethorphan premedication relieve cough during flexible bronchoscopy?

Premedication with dextromethorphan 1 hour prior to flexible bronchoscopy appears to alleviate cough slightly in patients under conscious sedation and on topical lignocaine, reports a recent study.

“Cough is invariably encountered during flexible bronchoscopy despite sedation and topical anaesthetics,” the investigators said, adding that the best cough suppressant during flexible bronchoscopy remains elusive.

In this single-centre study, the role of dextromethorphan premedication in relieving cough during flexible bronchoschopy was assessed in adults. The investigators randomized patients aged ≥18 years to receive dextromethorphan syrup 30 ml (90 mg) or an equal volume of placebo 1 hour before the procedure.

At the end of the procedure, the participants rated the severity of their cough, as well as discomfort, using a visual analogue scale. Bronchoscopists also rated the cough severity of the patients.

One hundred twelve patients were identified initially, of which 94 (median age 51 years, male-to-female ratio 2.13:1) were randomly assigned to either the dextromethorphan (n=47) or placebo (n=47) group.

The patient-rated median cough scores at the end of the procedure were 15 and 20 mm (p=0.03) in the dextromethorphan and placebo groups, respectively. No significant between-group differences were seen in patient-rated median cough scores at 1 hour (5 vs 6 mm; p=0.21), discomfort scores (12.5 vs 12.5 mm; p=0.49), and midazolam and lignocaine use.

In addition, the intervention group had a lower bronchoscopist-rated median cough score than the placebo group (26 vs 35 mm; p=0.09), but this did not reach significance.

“Further trials are needed to reiterate our findings with certainty,” the investigators said.