Effect of lidocaine on the ventilatory and airway responses to exercise in asthmatics.

An aerosol of 4% lidocaine was delivered during the last third of inspiration to patients with bronchial asthma while they were quietly breathing. After this procedure, both cough reflex (inhalation of 10% citric acid) and gag reflex (mechanical irritation of the larynx) were absent in all patients for 15 to 20 min. This type of anesthesia was tolerated well by all patients, and did not significantly influence baseline pulmonary function tests. On another day, this procedure was used prior to treadmill exercise testing. Anesthesia blocked the development of exercise-induced bronchoconstriction (EIB) after the exercise period, as measured by FEV1, FEF25-75%, Vmax70% TLC, and specific airway conductance (SGaw). It was also found that the degree of minute ventilation (VE), as measured during exercise with airway anesthesia, significantly decreased (p < 0.01) compared with VE measured during exercise without lidocaine. The results suggested that local anesthesia of the upper and large airways in patients with bronchial asthma can significantly inhibit EIB and significantly decrease VE during moderate exercise. It can be postulated that mucosal receptors in the upper and large airways are directly involved in the initiation of EIB, and that their stimulation may be responsible for increased ventilation during exercise.