A 52-year-old man presents with a blood pressure of 228/136 mmHg, severe headache, and fundoscopy reveals papilloedema with flame-shaped haemorrhages (hypertensive encephalopathy). His serum creatinine has risen from a baseline of 0.9 to 2.4 mg/dL acutely. What is the target blood pressure reduction in the first hour of treatment?
- A Normalise BP to < 130/80 mmHg within the first hour
- B Reduce systolic BP by 50–60 mmHg within 15 minutes
- C Reduce mean arterial pressure (MAP) by no more than 20–25% within the first hour ✓
- D Reduce MAP by 40–50% in the first 2 hours to rapidly relieve encephalopathy
Explanation
In hypertensive emergencies with end-organ damage, abrupt normalisation of blood pressure is dangerous due to impaired cerebral autoregulation — rapid lowering can cause watershed infarction, myocardial ischaemia, and renal ischaemia. Current JNC 8 and ESC 2023 hypertension guidelines recommend reducing MAP by no more than 20–25% within the first 1–2 hours, with subsequent gradual reduction over 24–48 hours toward < 160/100 mmHg. Exception: aortic dissection requires more aggressive reduction (systolic < 120 mmHg within 20 minutes). A 40–50% MAP reduction would be harmful. Normalising BP within 1 hour risks ischaemic complications.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
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Written and medically reviewed by the StethoPrep medical team.