Lidocaine sprayed down the endotracheal tube attenuates the airway-circulatory reflexes by local anesthesia during emergence and extubation.

Abstract

To determine whether lidocaine sprayed down the endotracheal tube (ETT) would attenuate airway-circulatory reflexes during emergence, we compared the reflex responses after endotracheal or IV lidocaine (IVL) in 75 patients receiving a standardized anesthetic protocol. At the end of surgery, the patients were divided into 3 groups (n = 25 for each group) and given no drug (Group 1), given 1 mg/kg of 2% lidocaine sprayed down the ETT 5 min before (Group 2), or given the same dose of IVL 3 min before extubation (Group 3). Blood pressure and heart rate were recorded at predetermined time points from 5 min (baseline) before until 5 min after extubation. The number of coughs per patient was continuously monitored during this period. The number (mean +/- SD) of coughs was decreased in Group 2 (4.5 +/- 3.7) compared with the control (10.2 +/- 6.0) (P < 0.01) with no difference for the control versus Group 3 (7.8 +/- 4.6). The increase in blood pressure was only attenuated immediately before extubation (P < 0.05), whereas the increase in heart rate was attenuated (P < 0.05) at all (except baseline) time points (P < 0.05) in Group 2 compared with the control with no difference for the control versus Group 3. The results indicate that lidocaine sprayed down the ETT suppresses the reflexes whereas using the same dose IVL does not, which is probably attributable to the mucosa-anesthetizing effect of lidocaine. Lidocaine sprayed down the endotracheal tube suppresses the airway-circulatory reflex responses whereas using the same dose IV lidocaine does not. This effect seems to be from the direct local anesthesia rather than from systemic absorption from the airway.