Small-Dose Dopamine Increases Epidural Lidocaine Requirements During Peripheral Vascular Surgery in Elderly Patients

摘要: UNLABELLED: We studied 20 patients over the age of 65 yr undergoing prolonged peripheral vascular surgery under continuous lidocaine epidural anesthesia, anticipating that increased hepatic metabolism caused by small-dose IV dopamine would lower plasma concentrations. Subjects were assigned (random, double-blinded) to receive either a placebo infusion or dopamine, 2 microg. kg(-1). min(-1) during and for 5 h after surgery. Five minutes was started, mL 2% injected through catheter. One-half hour later, at 10 mL/h begun. The temporarily decreased boluses added maintain T8 analgesic level. Arterial blood samples analyzed concentrations regularly Plasma continuously and, despite wide individual variation, similar two groups throughout observation period. During period, mean maximal concentration 5.8 +/- 2.3 microg/mL in control group 5.7 1.2 group. However, hourly requirement significantly different, 242 72 mg/h 312 60 (P < 0.03). At end Hour 4, last period when all still receiving infusion, total 1088 191 mg 1228 168 0.05). Despite very large doses (1650 740 mg, patients, 1940 400, patients) remained below 6 microg/mL, no patient exhibited signs symptoms toxicity. conclude requirements, presumably as consequence metabolism. IMPLICATIONS: tested drug increases liver local anesthetic determine if it prevent excessively amounts anesthesia elderly patients. Dopamine did not alter levels lidocaine, but increase dose adequate anesthesia.