Effects of inhaled lidocaine on exercise-induced asthma

Experiments were performed to determine if stimulation of afferent nerve endings in the respiratory mucosa plays a major role in the initiation of exercise-induced asthma. Five asthmatic subjects were studied in two sessions of 10 min treadmill exercise using an identical workload. In the control session the subjects were exercised without treatment; in the other session aerosol lidocaine (1.5 mg/kg) was inhaled from residual volume to total lung capacity before exercise was started. Pulmonary function tests were measured (1) to obtain baseline values before the aerosol inhalation or exercise was commenced, (2) 2-3 min after completion of lidocaine inhalation, and (3) 4 min after termination of exercise. In the control session the mean postexercise forced expiratory volume in 1 s (FEV1) and the mean forced expiratory flow during the middle half of forced vital capacity (FEF25-75%) were decreased to 61 and 44% of the baseline values, respectively. Similarly, with the lidocaine treatment the post-exercise FEV1 and FEF25-75% were decreased to 54 and 44% of the baseline values, respectively. These data indicate that the afferent nerves in the respiratory mucosa may not play a critical role in the development of exercise-induced asthma.