Effects of Hydralazine Pretreatment on Esmolol-induced Controlled Hypotension during Spine Surgery

Background: Controlled hypotension improves surgical field and decreases transfusion requirement in surgical patients and can be induced with various kinds of drugs including esmolol and hydralazine. Methods: This study examined the effect of a combination of esmolol and hydralazine as hypotensive agents in spine surgery. In the esmolol group (n = 15), after boluses of esmolol (0.5 mg/kg) injection, esmolol was infused to maintain the mean arterial pressure of 55-65 mmHg. In the hydralazine-esmolol group (n = 15), hydralazine (0.3 mg/kg) was administered 15 minutes before esmolol injection which was done in the same way as that of the esmolol group. Results: The mean arterial pressure decreased to the target range more rapidly in the hydralazine-esmolol group. The heart rate was increased by hydralazine, but reduced by esmolol. The cardiac output remained elevated after hydralazine injection in the hydralazine-esmolol group, and decreased significantly by esmolol in the esmolol group. The administered dose of esmolol was much less in the hydralazine-esmolol group than in the esmolol group. Conclusions: Our data suggest that hydralazine can enhance the efficacy of esmolol-induced controlled hypotension. It can reduce the requirement of esmolol and maintain a higher cardiac output during hypotension. (Korean J Anesthesiol 2006; 50: S 31~5)