Duration and toxicity of bupivacaine for topical anesthesia of the airway in the cat.

To assess bupivacaine as a topical anesthetic of the airway, 0.5 ml of 1, 2, and 4% bupivacaine was sprayed down the trachea of lightly anesthetized cats and the duration of anesthesia, systemic toxicity, and local toxicity was compared to that produced by 4% lidocaine. Two percent bupivacaine suppressed the cough reflex longer than 4% lidocaine with no increase in either local or systemic toxicity. Four percent bupivacaine produced arrhythmias in 5 of 10 cats in two groups and apnea in 4 of 6 cats. This study indicates that 2% would be an appropriate concentration to assess bupivacaine as a topical anesthetic of the airway in humans.