Comparison of laryngotracheal and ultrasonic nebulizer administration of lidocaine in local anaesthesia for bronchoscopy.

Inhalation of nebulized minute lidocaine droplets has been suggested to be a very safe and pleasant method to produce topical anaesthesia for bronchoscopy. We produced topical anaesthesia of the respiratory tract either by laryngotracheal spraying (LS) of lidocaine (439 +/- 85mg) or ultrasonic nebulizer administration (UNA) of lidocaine (462 +/- 81 mg) in 40 patients undergoing bronchoscopy. All patients also received an average of 15 mg of diazepam intravenously. Both modes of lidocaine administration produced adequate anaesthesia and were safe, but when rated on the visual analogue scale, both the efficacy of local anaesthesia and the cooperation of patients during bronchoscopy were better (P less than 0.05) after LS than those after UNA. The peak plasma concentrations of lidocaine (means +/- s.d.) were lower and occurred earlier after UNA (0.53 +/- 0.34 micrograms/ml at 5-15 min after administration) than those after LS (0.89 +/- 0.63 micrograms/ml at 15-25 min after spraying). The highest individual values measured (2.54 micrograms/ml after LS and 1.17 micrograms/ml after UNA) were much less than those reported toxic lidocaine plasma concentrations. It is concluded that bronchoscopy can be conducted under local anaesthesia as successfully and safely using inhalation of lidocaine droplets from an ultrasonic nebulizer as when using laryngotracheal spraying of lidocaine.