Airway anaesthesia and breathing pattern during exercise in normal subjects and in eucapnic patients with chronic...

In order to deprive vagal upper and large airway receptors, an aerosol of 4% lidocaine (240 mg) was delivered to eight normal subjects and to eight eucapnic patients with chronic obstructive pulmonary disease (COPD). After this procedure, gag reflex (mechanical irritation of the larynx) and cough reflex tested by an aerosol of 10% citric acid were absent in all subjects. The anaesthesia was tolerated well by all the subjects and did not influence baseline pulmonary function tests. Moreover, during exercise, before and after lidocaine, no significant difference in O2 intake (VO2) or in blood gases (measured in patients only) could be observed. After lidocaine administration, no significant changes were seen in any of the respiratory variables studied in normal subjects or in COPD patients compared to the basal conditions. This could indicate that vagal upper and large airway receptors do not play an important role for the breathing pattern and ventilatory drive during exercise either in normal subjects or eucapnic patients with COPD.