Controlled-analysis of the effects of inhaled lignocaine in exercise-induced asthma

Abstract

To determine whether anaesthesia of the intrathoracic airways would attenuate the development of exercise-induced asthma, we studied eight symptomless asthmatic patients by cycle ergometry after saline or lignocaine pretreatment while they were breathing air at 24 degrees C with 9.1 mg of H2O/l. Pulmonary mechanics were measured before and after the administration of each agent, and again five minutes after cessation of exercise. Sufficient lignocaine was administered to abolish the gag reflex and the cough response to aerosols of citric acid. Before exercise there were no significant differences for any lung function variable between the saline and lignocaine results. Equally, there were no significant differences between these agents for minute ventilation (VE) during exercise (VE lignocaine = 71.0 +/- 7.4 (SEM) l/min; VE saline 67.2 +/- 8.1 l/min;), or in the severity of the subsequent bronchospastic response (for example, the FEV1 with saline was 22.6 +/- 2.9% decrease, and with lignocaine 23.6 +/- 8.5%). Thus these results do not support the idea that there are thermally sensitive neural receptors in intrathoracic airways that play a role in the pathogenesis of exercise-induced asthma.