Effect of topical anaesthesia on the motor performance of vocal cords as assessed by tussometry.

Tussometry involves a continuous measurement of airflow produced by a cough manoeuvre displayed as an airflow-time wave. There is a rapid rise to its peak (cough peak flow rate) and the time taken to reach the peak (peak velocity time) is determined by the laryngeal opening at the onset of cough. Cough peak flow and peak velocity time were measured in 10 healthy volunteers before and after topical anaesthesia of the larynx with lignocaine 100 mg sprayed under indirect laryngoscopy. Adequacy of anaesthesia was established by touching the cords deliberately with a fibreoptic laryngoscope. All subjects had excellent anaesthesia of the larynx. However, cough peak flow rate and peak velocity time remained unchanged following topical anaesthesia. We conclude that topical anaesthesia of the larynx does not impair the motor performance of the vocal cords during a voluntary cough.