In the field of anesthesiology, there is wide debate on discontinuing angiotensin-converting enzyme inhibitor (ACEI) and angiotensin receptor blocker (ARB) therapy the day of noncardiac surgery. Although there have been many studies attributing perioperative hypotension to same-day ACEI and ARB use, there are many additional variables that play a role in perioperative hypotension. Additionally, restoring blood pressure in these patients presents a unique challenge to anesthesiologists. A case report is presented in which a patient took her ACEI the day of surgery and developed refractory hypotension during surgery. The evidence of ACEI use on the day of surgery and development of hypotension is reviewed, and additional variables that contributed to this hypotensive episode are discussed. Lastly, current challenges in restoring blood pressure are presented, and a basic model on treatment approaches for refractory hypotension in the setting of perioperative ACEI use is proposed. 1. Introduction Approximately 65 million Americans actively receive antihypertensive agents for elevated blood pressure . During surgery, beta-adrenergic blockers and alpha 2 agonists are routinely continued perioperatively because of their role in protecting the myocardium [2–5]. Additionally, calcium channel blockers are used in the perioperative period because of their reduction in myocardial ischemia, infarction, arrhythmias, and overall mortality [6, 7]. Since angiotensin-converting enzyme inhibitor (ACEI) attenuates the adrenergic response to stressful stimuli in cardiac, vascular, and cerebrovascular patients, ACEI is strongly recommended prior to and during these specific surgeries [8–11]. However, the use of ACEI and angiotensin receptor blocker (ARB) therapy in the preoperative period in noncardiac patients has been controversial because of its potential role in causing hemodynamic instability. Patients on chronic ACEI or ARB therapy have a dampened sympathetic response . Additionally, surgical patients can be volume depleted because of preoperative fasting, and this condition can cause additional stress during surgery. These combining factors result in reduced vascular capacitance and venous return, leading to decreased cardiac output and subsequent hypotension. To compensate for this hypotension, angiotensin II (ANG2) plays an important role in maintaining blood pressure through vasoconstriction. This vasoconstriction shunts blood away from the kidneys, bowels, and spleen [12, 13]. ANG2’s short-term effect is to maintain blood pressure through vasoconstriction
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