A 52-year-old man presents with a hypertensive emergency: BP 228/134 mmHg, GCS 13, papilloedema and retinal haemorrhages (hypertensive encephalopathy), creatinine rising from 1.2 to 2.8 mg/dL over 24 hours, and microangiopathic haemolytic anaemia on blood film. This represents hypertensive crisis with TMA (thrombotic microangiopathy). The most critical target for BP reduction in the first hour is:
- A Reduce mean arterial pressure by no more than 20–25% in the first hour, aiming for BP ~160/100 mmHg ✓
- B Reduce BP to < 120/80 mmHg within 1 hour using labetalol infusion
- C Immediate sodium nitroprusside infusion to normalise BP within 30 minutes to prevent further end-organ damage
- D BP should not be aggressively reduced; await autoregulation to restore cerebral flow before treatment
Explanation
ESC 2018 hypertensive emergency guidelines recommend reducing mean arterial pressure by no more than 20–25% in the first hour (to approximately 160/100 mmHg). Over-rapid reduction can precipitate cerebral, coronary, or renal ischaemia because cerebral autoregulation is chronically reset at higher pressures and sudden normalisation impairs perfusion. In hypertensive encephalopathy, the upper limit of autoregulation has been breached (cerebral oedema) but the lower limit is also shifted upward; rapid normalisation can paradoxically worsen ischaemia. Sodium nitroprusside carries cyanide toxicity risk and is generally avoided in preference for IV nicardipine, labetalol, or clevidipine.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
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Written and medically reviewed by the StethoPrep medical team.