Topical lidocaine through the bronchoscope reduces cough rate during bronchoscopy

Topical lidocaine is often administered through the flexible bronchoscope in an attempt to reduce excessive coughing and patient discomfort. With the increasing use of sedation, including opiates that possess central cough suppressant effects, and the potential for serious clinical toxicity, the need for evidence regarding the efficacy of topical lidocaine is important. This study assessed whether topical lidocaine through the bronchoscope could reduce cough and stridor rate.

A randomized controlled trial of 49 patients undergoing flexible bronchoscopy was conducted. Following sedation and topical anaesthesia to the upper airway, patients were randomized to receive either lidocaine 2% or placebo (N-saline) through the bronchoscope to the vocal cords and tracheobronchial tree. Cough and stridor rates were recorded by audiotape. Bronchoscopists and nurses assessed coughing with visual analogue scales.

There were no significant differences in baseline demographics and level of sedation between the two groups. The cough rate per minute (mean (SD)) was lower (P < 0.001) in the lidocaine group, 12.20 (7.99), n = 18, than in the placebo group, 27.50 (10.74), n = 31. The stridor rate was lower with lidocaine, 0.22 (0.60) per minute than with placebo 0.80 (1.35), but the difference was non-significant at P = 0.095. Both doctors' and nurses' scores for cough were significantly lower in the lidocaine group (P < 0.001 for both). Less midazolam 2.1 mg (1.1) was used with lidocaine than with placebo 3.4 mg (1.9), P = 0.02 and less fentanyl 81.9 mg (34.1) versus 98.4 mg (20.4), P = 0.04.

Topical lidocaine through the bronchoscope significantly decreased cough frequency and the total dose of sedation required during flexible bronchoscopy.