How quickly should blood pressure (BP) be lowered in a hypertensive emergency?

From the Guidelines

In a hypertensive emergency, blood pressure should be lowered rapidly, but carefully, with a goal to reduce systolic blood pressure to <140 mm Hg within the first hour, and then to normal levels over the next 24-48 hours, depending on the specific comorbidity and clinical presentation. The speed of blood pressure reduction is crucial, as it can impact morbidity, mortality, and quality of life. According to the 2017 ACC/AHA/AAPA/ABC/ACPM/AGS/APhA/ASH/ASPC/NMA/PCNA guideline for the prevention, detection, evaluation, and management of high blood pressure in adults 1, the therapeutic goal is to minimize target organ damage safely by rapid recognition of the problem and early initiation of appropriate antihypertensive treatment.

Some key considerations for blood pressure reduction in hypertensive emergencies include:

• The presence of comorbidities, such as acute aortic dissection, severe preeclampsia or eclampsia, and pheochromocytoma with hypertensive crisis, which require rapid lowering of systolic blood pressure to <140 mm Hg within the first hour 1
• The use of intravenous antihypertensive drugs, such as esmolol, labetalol, nicardipine, and nitroglycerin, which can be titrated to achieve the desired blood pressure reduction 1
• The importance of tailoring the medication choice to the patient's presentation, with consideration of contraindications such as avoiding beta-blockers like labetalol in acute heart failure or bronchospasm 1

A more recent guideline from the ESC Council on Hypertension 1 also emphasizes the importance of careful blood pressure reduction in hypertensive emergencies, with a focus on the type of acute organ damage and the target blood pressure. However, the 2017 ACC/AHA/AAPA/ABC/ACPM/AGS/APhA/ASH/ASPC/NMA/PCNA guideline 1 provides more specific guidance on the speed of blood pressure reduction and the use of intravenous antihypertensive drugs.

The specific medication choice and dosage should be individualized based on the patient's clinical presentation and comorbidities. For example, in patients with acute aortic dissection, esmolol or labetalol may be preferred, while in patients with acute coronary syndromes, esmolol, labetalol, nicardipine, or nitroglycerin may be used 1. Ultimately, the goal is to reduce blood pressure rapidly, but carefully, to minimize target organ damage and improve patient outcomes.

From the FDA Drug Label

With constant infusion, blood pressure begins to fall within minutes. It reaches about 50% of its ultimate decrease in about 45 minutes

• The speed to bring down BP in a hypertensive emergency with nicardipine (IV) is:
  • Within minutes for blood pressure to begin to fall
  • About 45 minutes to reach 50% of its ultimate decrease 2

From the Research

Hypertensive Emergency Management

• The goal in managing hypertensive emergencies is to lower blood pressure (BP) quickly to prevent further target-organ damage, but not so quickly that it causes hypoperfusion 3, 4, 5, 6, 7.
• The rate of BP reduction depends on the specific clinical situation, with most authors suggesting a reduction in mean arterial pressure of approximately 10% during the first hour and a further 10% to 15% during the next 2 to 4 hours 3, 4.
• In cases of aortic dissection, the systolic BP target is lower than 120 mm Hg, to be achieved during the first 20 minutes using a beta-blocker and a vasodilator 3, 4.
• For other hypertensive emergencies, parenteral antihypertensive therapy is typically used, with agents such as sodium nitroprusside, fenoldopam, nicardipine, and labetalol being commonly used 3, 4, 5.
• Oral antihypertensive therapy can usually be instituted after 6 to 12 hours of parenteral therapy, and the patient can be moved out of the intensive care unit 3, 4.

Hypertensive Urgency Management

• In contrast to hypertensive emergencies, hypertensive urgencies are characterized by an acute increase in blood pressure without signs or symptoms of acute target-organ damage 5, 6.
• In these cases, blood pressure should be lowered within 24 to 48 hours to avoid hypertensive target-organ damage, and hospitalization is not usually required 5, 6.
• Oral antihypertensive therapy is often sufficient, but further and continuing outpatient care is necessary to ensure adequate control of hypertension 6.

Special Considerations

• Patients with chronic hypertension have an altered autoregulation curve, and acute normotension can lead to hypoperfusion, so blood pressure should not be reduced too quickly or too far 3, 5.
• Certain conditions, such as aortic dissection or pulmonary edema, require rapid reduction of blood pressure to normal values, regardless of the risk of hypoperfusion 5.
• The selection of antihypertensive agents depends on the existing organ failure, as well as the reliable effectiveness and regulability of the applied antihypertensive 5.