According to JNC-7, the goal of therapy in hypertensive emergency is to reduce the mean arterial pressure (MAP) by no more than 25% of initial BP within minutes to 1 to 2 hours, and 10% to 15% of this reduction should occur in the first 30 to 60 minutes. For example, in a patient with a BP of 225/150 and the presence of TOD, the BP should be lowered to ~ 200/140 in the first 30 to 60 minutes and to 169/112 in the next 1 to 2 hours. The primary objective is to terminate ongoing TOD, but not to return the BP to "normal levels." The main danger of reducing the BP too rapidly is the possibility of precipitating coronary or renal ischemia. In hypertensive patients with cerebral hemorrhage, SAH, or acute brain infarction, lowering the BP too quickly reduces cerebral perfusion even further, thereby worsening hypoxia and causing death of brain tissue.
Immediate actions, if the patient is not already in an acute care setting, should follow the mantra of acute care nursing: IV, O2, and Monitor. In other words, ensure intravenous (IV) access, place patients on exogenous oxygen depending on O2 saturation levels or arterial blood gas results, place severely hypertensive patient on continuous EKG monitoring, insert an indwelling arterial line, and transfer immediately to an ICU setting. Remember to assess the patient's fluid status because, despite an elevated BP, he or she may be volume depleted. The drug of choice will depend on the clinical situation ( Table 4 ).
ACE Inhibitors (Enalapril, Oral or Enalaprit, IV)
These are the preferred drugs of choice in most forms of hypertensive crisis. The IV form, Enalaprit, is preferred in hypertensive emergency for acute BP reduction. For hypertensive urgency, an oral dose will take 30 to 60 minutes to achieve effect, and lowering of the BP indicates an "R" type HTN. ACEIs are effective in decompensated heart failure and acute coronary syndromes, but are contraindicated in pre-eclampsia and eclampsia.
Loop Diuretics (Furosemide Oral, IV)
These are effective as add-on treatments for afterload reduction in patients with hypertensive emergency and urgency due to heart failure, pulmonary edema, and renal failure. Doses should be increased until diuresis is achieved.
This is a potent second-generation calcium-channel blocker. It is useful in the management of severe HTN associated with chronic or acute renal failure, hemorrhagic and ischemic stroke, eclampsia, pheochromocytoma, hypertensive encephalopathy, and aortic aneurysm. It produces arterial vasodilation and decreases cardiac and cerebral ischemia. Nicardipine has the potential to precipitate reflex tachycardia and should not be used in patients with wide complex tachycardias. When given IV, the onset of action is 1 to 5 minutes; duration of action is 3 to 4 hours. It is considered as effective as nitroprusside but is easier to titrate and has fewer toxicities.
Labetolol (Oral, IV)
Labetolol is an α-1, β-1 adrenergic blocker that is effective in reducing BP in hypertensive crises. When given IV, the onset of action is 5 to 10 minutes; with an action duration of 3 to 6 hours. One advantage of labetolol is that it maintains cardiac output while reducing systemic vascular resistance. It is used for hypertensive emergency resulting from acute MI, aortic dissection, hemorrhagic and ischemic stroke, hypertensive encephalopathy, acute and chronic renal failure, and eclampsia.
Nitroprusside (Nipride, IV)
Nitroprusside is a commonly used direct-acting arterial and venous dilator, with a rapid onset of action that is frequently used as first-line therapy in hypertensive emergencies. The venous dilation reduces cardiac preload and produces profound reduction in BP. It is given IV at 0.25 to 10 μ/kg/min and requires continuous BP monitoring via an indwelling arterial line. Nipride must always be administered in a monitored setting (see Box). The onset of action is immediate and the duration of effect is 3 to 5 minutes. Careful titration of Nipride is required, as the BP will rebound within seconds to minutes once the drug is discontinued. An ACEI or a β-blocker must be on-board before discontinuing Nipride. Nipride may also be used with labetolol or esmolol in acute aortic dissection ( Table 5 ).
This is a newer selective peripheral dopamine receptor agonist. The onset of action is 4 to 5 minutes, with a duration of action of less than 10 minutes. It is used for short-term treatment, up to 48 hours. Fenoldopam lowers BP, improves renal profusion, and promotes dieresis; however, it does not affect cardiac preload. There are indications that fenoldopam may be as effective as Nipride in hypertensive emergency, but without the tolerance or rebound BP problems of Nipride. It remains nonformulary in many institutions due to the higher cost.
Esmolol (Brevibloc, IV)
Esmolol is a cardio-selective, short-acting β-adrenergic blocker given IV to acutely lower systolic BP, SVR, heart rate, MAP, cardiac output, and stroke volume. Esmolol is approved only for the treatment of supraventricular tachycardia, but is often used for treating HTN emergencies related to coronary insufficiency and aortic dissection. It is also useful in peri- and postoperative HTN associated with anesthesia. The onset of action occurs 1 to 2 minutes after bolus and the duration of action is 10 to 30 minutes. Due to its rapid onset and short half-life, it is a drug that can be readily titrated for the desired BP. It should not, however, be used in patients with diabetes, HF, or COPD due to their sensitivity to β-blocking agents.
Central Alpha-receptor Agonists (Clonidine, Aldomet, Guanfacine, Oral)
These older oral antihypertensive agents are still widely used in the community setting. Abrupt discontinuation results in severe rebound HTN. If this is the case, the first step should be to reinstate the drug and to further reduce the BP with IV or oral labetolol, phentolamine, or esmolol.
Journal for Nurse Practitioners. 2010;6(5):338-346. © 2010 Elsevier Science, Inc.
Cite this: Hypertensive Crisis in an Era of Escalating Health Care Changes - Medscape - May 01, 2010.