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
- Improperly managed hypertension
- Renal vascular disease
- Pheochromocytoma
- Accelerated essential hypertension
Clinical features of hypertensive emergencies
- Severely elevated blood pressure ( >180/120mmHg)
- Headaches, malaise, vomiting, dizziness, blurred vision, chest pain, palpitations, dyspnoea, oliguria
- Fundoscopic changes
- Evidence of left ventricular failure
- Changes in level of consciousness
Complications of hypertensive emergencies
- Cerebrovascular accident
- Target organ damage
- Myocardial infarction
- Cardiac failure
- Renal failure
- 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