Attenuation of circulatory response to laryngoscopy and tracheal intubation: a comparison of two methods of topical anaesthesia.

Circulatory responses to laryngoscopy and endotracheal intubation were compared between three groups of patients, two of which were subjected to a procedure of topical anaesthesia before induction of general anaesthesia. Topical anaesthesia, achieved with either a lidocaine dose aerosol or by gargling with viscous lidocaine, attenuated the magnitude of the pressor response to laryngoscopy and intubation but had no effect on the heart rate response. Lidocaine aerosol had some advantages over viscous lidocaine; these were the significantly smaller haemodynamic response to the local anaesthetic procedure itself and probably shorter duration of the circulatory changes produced by intubation. It is concluded that both of these simple methods are relatively ineffective in preventing haemodynamic changes associated with laryngoscopy and intubation and should probably be combined with another preventive method.