• Shahbaz R Arain, Julie K Freed, Jutta Novalija, Paul S Pagel, and Thomas J Ebert.
• Anesthesia Department, Clement J. Zablocki Veterans Affairs Medical Center and the Medical College of Wisconsin, Milwaukee, WI.
• J. Cardiothorac. Vasc. Anesth. 2016 Dec 1; 30 (6): 1479-1484.

ObjectiveThe mechanism of perioperative hypotension in patients taking an angiotensin-receptor blocker up to the time of surgery remains unclear. This study tested the hypothesis that short-term angiotensin-receptor blocker treatment attenuated the sympathetic and vascular responses to autonomic stimuli in volunteers undergoing anesthesia.DesignRandomized, crossover, blinded, pilot design.SettingZablocki Veterans Affairs Medical Center, Milwaukee, WI.ParticipantsThe study comprised 8 male and 6 female healthy, young volunteers (age 23±1.2 years [mean±standard error of the mean]).InterventionsVolunteers were studied after receiving oral placebo or 50 mg of losartan (angiotensin-receptor blocker) for 3 days before each test day. The effectiveness of angiotensin-receptor blocker treatment was confirmed using the mean arterial blood pressure response to intravenous angiotensin II (1-µg bolus). Eight volunteers underwent direct mean arterial pressure and forearm bloodflow measurements during conscious baseline, a cold pressor test, induction of anesthesia, tracheal intubation, maintenance of anesthesia with 1 minimum alveolar concentration of sevoflurane, and airway irritation with 12% desflurane. Six volunteers experienced mean arterial pressure responses to 0.1 mg of phenylephrine at baseline and during 1 minimum alveolar concentration of sevoflurane.Measurements And Main ResultsComparisons were made over time and across groups. Angiotensin-receptor blocker treatment significantly reduced-mean arterial pressure and forearm vascular resistance (forearm blood flow/mean arterial pressure) over time and blocked the mean arterial pressure response to angiotensin-II challenge. The changes in mean arterial pressure and forearm vascular resistance in response to all stressors did not differ between treatments. Mean arterial pressure increases from phenylephrine were preserved.ConclusionsIn healthy, young volunteers, sympathetically-mediated responses from the short-term use of an angiotensin-receptor blocker were not altered and most likely did not contribute to perioperative hypotension during the intraoperative period.Published by Elsevier Inc.

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