ACEIs Before Surgery: Know When to Hold 'em

To say the least, the numbers are impressive: as many as 60 million Americans have hypertension!¹ Most of these persons are receiving antihypertensive therapy, often with more than one agent. Again, many in this cohort will require surgery, both electively and emergently. Since antihypertensive medications are designed to lower blood pressure, is it possible that some have been incriminated in lowering perioperative blood pressure too much? Angiotensin-converting enzyme inhibitors (ACEIs) seem to be mentioned in this regard frequently and, in fact, have been accused of leading to treatment-refractory hypotension in the setting of general anesthesia.

When ACEIs are ingested anywhere from 8 to 24 hours before general anesthesia, intraoperative hypotension is more common.^1,2 The consequent hypotension can, on occasion, be unresponsive to typical corrective maneuvers, such as volume expansion or administration of ephedrine or phenylephrine.^1,2 The hypotension can be especially problematic in persons undergoing cardiopulmonary bypass, and the critical hypotensive situation as a result has been called vasoplegic syndrome.^1,3 So, should this missive end here with an unequivocal recommendation regarding ACEIs in the perioperative period? Sorry, it is not that straightforward. Let us count the ways:
• Although the American College of Cardiology (ACC) and American Heart Association (AHA) guidelines on perioperative care recommend holding certain antihypertensives in particular surgical settings, the “unequivocal” statement for ACEIs is lacking.¹
• In general, the incidence of both hypotension and blood pressure lability during general anesthesia is increased in patients with hypertension per se (ie, even without therapy).¹
• Extrapolation of the evidence for the specific contributions of ACEIs, compared with other drugs, remains “controversial.”¹

Some of the missing puzzle pieces may appear in updates to the 2007 guidelines from the ACC and AHA. In the meantime, what should primary care physicians do?
• Since data suggest that only severe hypertension (> 180/> 110 mm Hg) should be strictly controlled before surgery,⁴ in most instances, holding ACEIs would be a good idea.
• Communicate with the surgeon and the anesthesiologist. What is their preference? The anesthesiologist is usually capable of treating high blood pressure in the operating room. This would make holding any antihypertensive much easier.
• Cardiac bypass surgery warrants a special caveat. Vasoplegic syndrome is a nightmare, although it may respond to vasopressin and/or methylene blue.¹ I would not feel comfortable without holding ACEIs before this variety of surgery.

When you see your patients for the assessment of risk before surgery, be cognizant that any antihypertensive, but especially ACEIs, may cause hypotension if not discontinued in the perioperative period. Share updated medication lists with surgeons and anesthesiologists. They are your consultants. In persons without severe hypertension, holding may be far better than continuing.

References
1. Thoma A. Pathophysiology and management of angiotensin-converting enzyme inhibitor-associated refractory hypotension during the perioperative period. AANA J. 2013;81:133-140.
2. Comfere T, Sprung J, Kumar MM, et al. Angiotensin system inhibitors in a general surgical population. Anesth Analg. 2005;100:636-644.
3. Papadopoulos G, Sintou E, Siminelakis S, et al. Perioperative infusion of low dose vasopressin for prevention and management of vasodilatory vasoplegic syndrome in patients undergoing coronary artery bypass grafting: a double-blind randomized study. J Cardiothorac Surg. 2010;5:17.
4. Rutecki GW. Treating hypertension in the hospital: a few scenarios that challenge primary care. http://www.consultantlive.com/conference-reports/ash2013/content/article/10162/2143447. May 22, 2013. Accessed September 7, 2013.