[The effects of intravenous nicardipine on jugular venous oxygen saturation]

We investigated the effects of intravenous nicardipine on jugular venous oxygen saturation (SjO2) in patients undergoing superficial temporal artery-middle cerebral artery anastomosis. Anesthesia was induced with intravenous thiamylal and fentanyl, and maintained by isoflurane and nitrous oxide in oxygen. In the presence of stable condition after the induction, nicardipine 0.5 microgram.kg-1.min-1 was administered intravenously for 180 minutes. Mean arterial pressure, heart rate, SjO2 and bladder temperature were recorded. Three hours after continuous infusion of nicardipine, plasma levels of nicardipine in artery and jugular vein were measured by liquid chromatography. The arterial concentration of nicardipine reached 23.9 +/- 8.06 ng.ml-1. The area under the curve between the arterial and jugular venous nicardipine during infusion was significantly different. Mean arterial pressure was reduced in response to administration of nicardipine. There were no significant changes in heart rate, bladder temperature and SjO2. We concluded that the current dose of nicardipine reached effective concentration for systemic hypotension without influencing SjO2.