Acta Anaesthesiol Scand 2006; 50: 863–868 Printed in Singapore. All rights reserved Copyright # Acta Anaesthesiol Scand 2006 ACTA ANAESTHESIOLOGICA SCANDINAVICA doi: 10.1111/j.1399-6576.2006.01048.x The effect of esmolol-induced controlled hypotension in combination with acute normovolemic hemodilution on cerebral oxygenation S.-H. HAN 1 , J.-H. BAHK 1 , J.-H. KIM 1 , Y.-J. LIM 1 , C.-D. PARK 1 , S.-H. DO 1 and Y.-S. PARK 2 1 Department of Anesthesiology, Seoul National University, College of Medicine and 2 Laboratory of Statistical Information Analysis, Hanyang University, College of Natural Sciences, Seoul, South Korea Background: It is possible to perform acute normovolemic hemodilution (ANH) in combination with controlled hypotension (CH). In this randomized prospective study, we examined the effect of the combination of ANH and CH on cerebral oxygena- tion using near-infrared spectroscopy. Methods: Fifty-six patients undergoing major orthopedic surgery were randomly assigned to either group A (ANH only) or group CH (CH in combination with ANH). In group CH, CH was induced with esmolol. The regional cerebral oxygen saturation (rSO 2 ) was monitored continuously and was compared between the two groups before and after ANH, 30 min (OP 30 ) and 90 min (OP 90 ) after the beginning of surgery and after the completion of surgery. Results: The value of rSO 2 was the same in both groups in the absence of CH (at baseline: group A, 70.1  6.0%; group CH, 69.9  6.7%; after surgery: group A, 64.5  4.9%; group CH, 64.3  5.8%). However, in the presence of CH, rSO 2 values were significantly lower in group CH than in group A (at OP 30 : group A: 60.4  3.4%; group CH, 55.9  7.3%; P < 0.01; at OP 90 : group A, 58.3  5.2%; group CH, 53.5  6.5%; P < 0.001). The number of patients with rSO 2 < 50% was significantly higher in group CH (14.3%) than in group A (3.8%). Conclusion: ANH in combination with esmolol-induced CH causes a significant decrease in cerebral oxygen saturation compared with ANH alone. Accepted for publication 3 March 2006 Key words: acute normovolemic hemodilution; controlled hypotension; cerebral oxygenation. # Acta Anaesthesiologica Scandinavica 50 (2006) T HERE is an increasing need to reduce patients’ exposure to homologous blood as a result of transfusion-associated complications. Acute normo- volemic hemodilution (ANH) and controlled hypo- tension (CH) are commonly used techniques to reduce homologous transfusion. To minimize trans- fusion, ANH can be performed in combination with CH (1, 2). Esmolol, a selective b 1 blocker with a short duration of action, is used to induce CH (3). Although an effect of esmolol-induced CH in combination with ANH on systemic oxygen metabolic balance has been reported (2), their effect on cerebral oxygenation has not been investigated. When ANH and esmolol-induced CH are used simultaneously in a patient, cerebral oxygenation can be a problem, as the former decreases arterial oxygen content and the latter decreases cardiac output (CO) and cerebral perfusion pressure (2). Near-infrared spectroscopy (NIRS), which uses two wavelengths (730 and 810 nm) of near-infrared light, measures the ratio of oxyhemoglobin to total hemoglobin in a field beneath the sensor. This ratio is expressed as a percentage of regional cerebral oxygen saturation (rSO 2 ) (4, 5). NIRS has been used for non- invasive continuous assessment of cerebral oxygen- ation status during various procedures (6–8). We conducted a prospective randomized study to compare the changes in rSO 2 during major ortho- pedic surgery performed under ANH alone or under a combination of ANH and CH using NIRS. Methods This study was approved by the institutional ethics committee (Committee on Human Research of Seoul National University Hospital and Seoul National University Bundang Hospital), and written informed consent was obtained from all participants. Patients scheduled for elective posterior lumbar interbody 863