Clearance by voluntary coughing and its relationship to subjective assessment and effect of intravenous bromhexine.

The elimination of 6 micrometers radioactively tagged teflon particles by 1-2 min of voluntary coughing was studied by profile scanning in 12 patients with tracheobronchial hypersecretion. The patients were tested on 2 different days 40-50 min after receiving 8 mg bromhexine (4 mg in two patients) and placebo intravenously according to a double blind cross-over design. Bromhexine did not influence the elimination of test particles in the nine patients in whom the measurements were technically satisfactory. When asked to identify the day they received bromhexine, the patients failed to do so. However, eight of the nine patients, in whom clearance measurements could be performed, believed they had received bromhexine on the day when most particles were eliminated (P less than 0.01), which coincided with the day on which coughing was easiest. It is suggested that self-assessment of the efficacy of coughing might be a simple, yet reliable technique for studying the short-term influence of drugs on tracheobronchial clearance by coughing.