Hepatic clearance of lidocaine during N2O anesthesia in dogs

Lidocaine catabolism under N2O anesthesia was evaluated in 5 dogs given a lidocaine infusion of 2 mg/kg/min for 20 minutes. Comparison of results with those of a prior similar study with halothane to be significantly faster in the animals given N2O. The extraction ratio for lidocaine, which did not vary with its arterial concentration, was significantly lower with halothane than with N2O. Decreased hepatic catabolism of drugs such as lidocaine should be anticipated in patients anesthetized with potent inhalation agents such as halothane.