Hypertensive Emergencies

Introduction

Hypertensive emergency is a condition where there is a severely elevated blood pressure (>180/120 mmHg) with evidence of target organ damage such as:

  • Neurologic (e.g. altered consciousness)
  • Cardiovascular (myocardial ischeamia, left ventricular failure)
  • Renal deterioration
  • Fundoscopic abnormalities

Presentations include:

  • Aortic dissection
  • Hypertensive encephalopathy
  • Malignant hypertension
  • Eclampsia

Aetiology of hypertensive emergencies

  1. Improperly managed hypertension
  2. Renal vascular disease
  3. Pheochromocytoma
  4. Accelerated essential hypertension

Clinical features of hypertensive emergencies

  1. Severely elevated blood pressure( >180/120mmHg)
  2. Headaches, malaise, vomiting, dizziness, blurred vision, chest pain, palpitations, dyspnoea, oliguria
  3. Fundoscopic changes
  4. Evidence of left ventricular failure
  5. Changes in level of consciousness

Complications of hypertensive emergencies

  1. Cerebrovascular accident
  2. Target organ damage
  3. Myocardial infarction
  4. Cardiac failure
  5. Renal failure
  6. Death

Investigations

  • Plain chest radiograph
  • Echocardiography
  • Full Blood Count
  • Urea, Electrolytes and Creatinine
  • Urinalysis

Treatment for hypertensive emergencies

Treatment objectives

  • 20 to 25% reduction in MAP in 1 to 2 hours
  • Further titration based on symptoms within 2 to 6 hours
  • Lower pressures may be indicated
    for patients with aortic dissection
  • Initiate/re-initiate long term therapy to normotensive levels

Drug treatment

Typical first-line drugs include nitroprusside, fenoldopam, nicardipine, and labetalol
Sodium nitroprusside:

  • 0.3 μg/kg/min intravenously initially, 0.5-6 μg/kg/min maintenance (maximum of 6 μg/kg/min)

Caution

  • Stop infusion if response is unsatisfactory after 10 minutes at maximum dose
  • Lower doses in patients already on antihypertensives
  • Hypotension may occur
  • Monitor blood cyanide and thiocyanate concentrations
  • Discontinue if adverse drug reaction to metabolites develop: tachycardia, sweating,
    hyperventilation, arrhythmias, acidosis)
  • Reduce infusion over 15 – 30 minutes to avoid rebound effect when stopping therapy