EFFECT OF TOPICAL ANESTHESIA 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 ri se to its peak (cough peak flow rate) and the time taken to I each the peak (peak velocity time) is determined by the laryngeal opening at t he onset of cough. Cough peak flow and peak velocity time were measure d in 10 healthy volunteers before and after topical anaesthesia of the larynx with lignocaine 100 mg sprayed under indirect laryngoscopy. Ad equacy of anaesthesia was established by touching the colds deliberate ly with a fibreoptic laryngoscope. All subjects had excellent anaesthe sia of the larynx. However, cough peak flow rate and peak velocity tim e remained unchanged following topical anaesthesia. We conclude that t opical anaesthesia of the larynx does not impair the motor performance of the vocal cords during a voluntary cough.