Inhibition of respiratory reflexes by local anesthetic aerosols in dogs and rabbits.

The effects of inhalation of 100 breaths of bupivacaine hydrochloride (5 percent solution in saline) on the cough reflex, the Breuer-Hering inflation, reflex, and the duration of apnea and bronchoconstriction produced by histamine aerosol were studied in nine anesthetized dogs. Cough was abolished in every animal; the duration of the inflation reflex was shortened from 47 +/- 4.6 s (mean plus or minus SE) to 16 +/- 3.4 s. The duration apnea produced by histamine was abolished or shortened and the rise in resistance was diminished from 170 plus or minus 22 per cent (control) to 49 +/- 6 per cent (after bupivacaine). These reflexes returned toward control values within 45 min. Bupivacaine inhibited the bronchoconstriction produced by electrical stimulation of the distal ends of cut vagus nerves both in dogs and in rabbits, but it did not alter the rise in resistance produced by histamine aerosol in vagotomized dogs. We conclude that administration of bupivacaine aerosol produces a reversible blockage of both afferent and efferent nervous activity in airways without abolishing the ability of smooth muscles to contract.