What is the appropriate reduction in Blood Pressure (BP) in a hypertensive emergency?

From the Guidelines

In a hypertensive emergency, blood pressure should be lowered by 20-25% within the first hour, then gradually to 160/100 mmHg over the next 2-6 hours, as recommended by 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.

Key Considerations

• The goal is to reduce pressure enough to prevent further organ damage while maintaining adequate perfusion.
• Continuous monitoring of BP and organ function is essential during treatment.
• The specific target BP and rate of reduction may vary depending on the patient's condition and affected organs.

Initial Management

Initial management typically involves intravenous medications such as:

• Labetalol: 20-80 mg bolus every 10 minutes, or 0.5-2 mg/min infusion
• Nicardipine: 5-15 mg/hour infusion, titrated every 5-15 minutes
• Clevidipine: 1-2 mg/hour, doubled every 90 seconds until target BP, maximum 32 mg/hour

Special Considerations

• In aortic dissection, a more aggressive reduction to systolic BP <120 mmHg within 20 minutes may be necessary 1.
• In patients with acute ischemic stroke, BP lowering is generally withheld, unless the patient is a candidate for thrombolytic therapy, in which case the target BP is <185/110 mmHg 1.
• In patients with acute hemorrhagic stroke, the target BP is <180/105 mmHg 1.

Long-term Management

After initial stabilization, transition to oral medications for long-term management, with careful monitoring of BP and organ function to prevent further complications 1.

From the FDA Drug Label

The time course of blood pressure decrease is dependent on the initial rate of infusion and the frequency of dosage adjustment. For a gradual reduction in blood pressure, initiate therapy at a rate of 5 mg/hr. If desired blood pressure reduction is not achieved at this dose, increase the infusion rate by 2.5 mg/hr every 15 minutes up to a maximum of 15 mg/hr, until desired blood pressure reduction is achieved. In patients with mild-to-moderate chronic stable essential hypertension, nicardipine hydrochloride injection (0.5 to 4 mg/hr) produced dose-dependent decreases in blood pressure, although only the decreases at 4 mg/hr were statistically different from placebo. At the end of a 48-hour infusion at 4 mg/hr, the decreases were 26 mmHg (17%) in systolic blood pressure and 21 mmHg (20%) in diastolic blood pressure.

The appropriate reduction in Blood Pressure (BP) in a hypertensive emergency is not explicitly stated in the provided drug labels. However, based on the information provided, nicardipine hydrochloride injection can produce dose-dependent decreases in blood pressure.

• The decreases in blood pressure can be as much as 26 mmHg (17%) in systolic blood pressure and 21 mmHg (20%) in diastolic blood pressure at an infusion rate of 4 mg/hr.
• The infusion rate can be increased by 2.5 mg/hr every 15 minutes up to a maximum of 15 mg/hr until the desired blood pressure reduction is achieved 2.
• The mean time to therapeutic response for severe hypertension was 77 ± 5 minutes with an average maintenance dose of 8.0 mg/hr 2.

From the Research

Reduction in Blood Pressure in Hypertensive Emergency

The reduction in blood pressure (BP) in a hypertensive emergency is a critical aspect of management. According to various studies:

• 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 is suggested 3, 4.
• A maximum BP reduction of 20-25% within the first hour and then to 160/110-100 over the next 2-6 hours is considered appropriate, with a further gradual decrease over the next 24-48 hours to reach normal BP levels 5.
• The blood pressure should be reduced rapidly, but not to the normal value, by approximately 20-30% of the baseline value 6.
• However, in certain cases such as aortic dissection, the systolic BP target is lower than 120 mm Hg, to be achieved during the first 20 minutes 3, 6.

Key Considerations

Some key considerations in reducing blood pressure in a hypertensive emergency include:

• The rate and extent of BP level lowering should be tailored to the type and extent of organ damage 7.
• Patients with chronic hypertension have an altered autoregulation curve, and acute normotension would lead to hypoperfusion in these patients 6.
• Parenteral treatment is preferred in hypertensive emergencies, as it allows for rapid and regulated reduction in blood pressure 6.
• The selection of antihypertensive medication depends on the existing organ failure, as well as the reliable effectiveness and regulability of the applied antihypertensive 6.