According to the American Heart Association and the American College of Cardiology, almost half of all American adults have elevated blood pressures, or hypertension (1). Hypertension, traditionally defined as a measured blood pressure persistently ≥140/90 mm Hg, is one of the major contributors to premature morbidity and mortality in the United States (2). Uncontrolled hypertension can lead to severe end-organ damage in the vasculature, heart, brain, kidneys, and eyes. Because of the growing public health concern that is associated with hypertension and the importance of hemodynamics to anesthesia and surgery, it is important that anesthesia providers are knowledgeable about the perioperative management of the hypertensive patient, especially in the case of uncontrolled hypertension.
Hypertension is the single greatest risk factor for cardiovascular disease, accounting for an estimated 50% of deaths from coronary artery disease and stroke. As a result of the nation’s aging population, obesity epidemic, and increasing adoption of sedentary lifestyles, the prevalence of hypertension will continue to rise (3). Uncontrolled hypertension during surgery and anesthesia can be harmful, and it is important to be prepared to quickly intervene.
The ideal pharmacologic agent for the treatment of uncontrolled hypertension during surgery and anesthesia should be rapid-acting, easily titrated, safe, and relatively inexpensive. Currently, many options are available, each with distinct advantages and disadvantages (4). Labetalol is a combined selective α1-adrenergic and nonselective β-adrenergic blocker, and is considered a first-line agent for uncontrolled hypertension. Labetalol works to reduce systemic vascular resistance without reducing total peripheral blood flow, thus preserving cerebral, renal, and coronary perfusion. Additionally, labetalol is often used in the setting of pregnancy-induced hypertensive crises, as it cannot cross the placenta (4). The hypotensive effect of labetalol begins within 2 to 5 minutes after IV administration, reaching a peak at 5 to 15 minutes following administration, and lasting for about 2 to 4 hours. However, labetalol should be used with caution in patients with heart failure and avoided in patients with severe sinus bradycardia, heart block, and/or asthma (4).
Nicardipine is a short-acting dihydropyridine calcium channel blocker (CCB) available for both IV and oral use. Likely due to its augmentation of both cardiac and systemic vasodilation, IV nicardipine has been shown to reduce both cardiac and cerebral ischemia. Typically, nicardipine dosage is independent of the patient’s weight, with an initial infusion rate of 5 mg/h, increasing by 2.5 mg/h every 5 minutes to a maximum of 15 mg/h until the desired BP reduction is achieved. The onset of action of IV nicardipine is from 5 to 15 minutes, with a duration of action of roughly 4 to 6 hours (4).
Enalaprilat, an ACE inhibitor available for intravenous (IV) administration, has been studied extensively in the perioperative setting (4). In general, ACE inhibitors have shown efficacy in treating hypertension associated with congestive heart failure and in the prevention of worsening renal function in patients with either diabetic or nondiabetic nephropathy. Enalaprilat is administered as an IV injection of 1.25 mg over 5 minutes every 6 hours, titrated by increments of 1.25 mg at 12- to 24-hour intervals up to a maximum of 5 mg every 6 hours (4). While the advantages of enalaprilat include a lack of reflex tachycardia and minimal effect on intracranial pressure, a disadvantage is that ACE inhibitors (in general) have the potential to cause acute renal failure in patients when mean arterial pressure is insufficient to support renal perfusion. Since surgical patients are often at an increased risk for circulatory decompensation in the postoperative period, ACE inhibitors should not be considered first-line agents in the treatment of acute intraoperative hypertension (4).
References
1. Gill R, Goldstein S. Evaluation and Management of Perioperative Hypertension. In: StatPearls. Treasure Island (FL): StatPearls Publishing; August 7, 2023.
2. Yancey R. Anesthetic Management of the Hypertensive Patient: Part I. Anesth Prog. 2018;65(2):131-138. doi:10.2344/anpr-65-02-12
3. Elliott WJ. Systemic hypertension. Curr Probl Cardiol. 2007;32(4):201-259. doi:10.1016/j.cpcardiol.2007.01.002
4. Varon J, Marik PE. Perioperative hypertension management. Vasc Health Risk Manag. 2008;4(3):615-627. doi:10.2147/vhrm.s2471