Hypertensive Emergencies Definition
Hypertensive emergencies is a severe elevation in blood pressure complicated by acute target organ dysfunction, such as coronary ischemia, stroke, intracerebral or subarachnoid haemorrhage, pulmonary oedema, acute renal failure, accelerated malignant hypertension, hypertensive encephalopathy, acute aortic dissection, acute left ventricular failure, acute myocardial infarction, acute glomerulonephritis, eclampsia, severe epistaxis, perioperative hypertension, etc.
Hypertensive emergency is different from hypertensive crisis and hypertensive urgencies. Hypertensive crisis is a severe elevation in blood pressure, generally a systolic blood pressure more than 220 mm Hg and or diastolic blood pressure more than 120 mm Hg (JNC-VII, 2003). And, hypertensive urgency is a severe elevation in blood pressure without evidence of target organ deterioration.
Hypertensive Emergencies Prevalence
Hypertensive crisis represented 27 % of all medical emergencies encountered over a year interval (Zampaglione et al, Turin, Italy, 1996).
In Patients with untreated primary hypertension before the availability of modern antihypertensive therapies, the incidency of accelerated hypertension with pupil-oedema was 7 % (Cahhoun D.A, Oparil S, N. Engl. J. Med 332: 1029, 1995).
Hypertensive emergencies occur most frequently in patients previously diagnosed with primary hypertension but who are non compliant. At present, there are about 1 % of patient with primary hypertension will progress to an accelerated-malignant form.
Hypertensive Emergencies Prognosis
In 1939, Keith et al found that patients with hypertension and grade IV retinopathy had a mean survival of 10.5 months, with no survivors at 5 years.
In 1958, Dustan et al found that among 84 patients being treated for malignant hypertension, 70 % survived 1 year and 33 % survived 5 years.
In the 1960s, with use of more effective and better tolerated anti hypertensive agents, 5 year survival rates were 50 to 60 %.
In the 1970s, with increase use of dialysis 5 year survival rates about 75 %. Current survival of patients with severe hypertension approaches that of patients with uncomplicated primary hypertension.
Hypertensive Emergencies Evaluation
Initial evaluation of patients with a hypertensive emergency is divided into history, physical examination and laboratory evaluation.
In history, we have to ask our patient about prior diagnosis and treatment of his (her) hypertension; intake of pressor agent, such as street drugs, sympathomimetics; and also symptom of cerebral, cardiac, and visual dysfunction.
In physical examination, we have to examine their blood pressure, neurological status, cardiopulmonary status, body fluid volume assessment, peripheral pulses, and we can also take funduscopy.
In laboratory evaluation, we have to evaluate packed cell volume and blood smear; urine analysis; chemistry, such as creatinine, glucose and electrolytes; electrocardiogram; PRA and aldosterone if primary aldosteronism is suspected; PRA before and 1 hour after 25 mg Captopril if renovascular hypertension is suspected; spot urine for metanephrine if pheochromocytoma is suspected; and, chest radiograph if heart failure or aortic dissection is suspected.
Hypertensive Emergencies Treatment
The goal of hypertensive emergencies therapy is to reduce systemic vascular resistance. The approach is to initially reduce mean arterial pressure by about 25 % with further reductions accomplished more gradually. In general, the initial reduction should be achieved over a period of 1 to 2 hours with less rapid reduction over the ensuring 6 hours to a diastolic blood pressure of about 100 mm Hg. With the exception of patients with aortic dissection, the blood pressure should not be reduce to normotensive and especially hypotensive levels, as target organ hypoperfusion may results.
Current Recommendation of the AHA
- hypertension in the setting of acute ischemic stroke should only be treated rarely and cautiously;
- for diastolic blood pressure more than 120-130 mm Hg, objective reduction 20 % in the first 24 hours;
- abandon oral nifedipine;
- short acting intravenous such as labetalol, nicardipine, and fenoldopam;
- SNP increase intracranial pressure, cyanide poisoning.
A Case with Intracerebral Hematoma
Hypertension serves to protect cerebral blood flow in the setting of high intracranial pressure. Treat if systolic blood pressure is more than 200 mm Hg or diastolic blood pressure is more than 110 mmHg. We have to remember that the rate of decline in blood pressure was independently associated with increased mortality.
Management of Hypertensive Emergencies Based on JNC-VII Recommendation
- Reduce mean arterial blood pressure no more than 25 % over 2 hours then reduce to 160 / 100 mm Hg within 2-6 hours;
- Avoid excessive falls in blood pressure; titrate with intravenous anti-hypertensive.
- Guideline of treatment based on consensus expert.
End-Organ Complication of Hypertensive Emergencies
Aortic. The complication of aortic is aortic dissection. The therapeutic considerations are beta-blockade, labetolol (decrease dp/dt), sodium nitroprusside with beta blockade, and avoid isolated use of pure vasodilators.
Brain. The complications of brain are hypertensive encephalopathy, cerebral infarction or hemorrhage. The therapeutic considerations are avoid centrally acting antihypertensive drugs such as clonidine, and avoid centrally acting agents in order to avoid rapid decreases in blood pressure.
Heart. The complications of heart are myocardial ischemia, myocardial infarction and heart failure The therapeutic considerations are intravenous glyceryl trinitrate, beta-blockade; diuretics and ACE inhibitors are useful; beta-BLOCKERS with caution.
Kidney. The complication of kidney is renal insufficiency. The therapeutic considerations are: diuretics with cautions; calcium antagonists is useful.
Placenta. The complication of Placenta is eclampsia. The therapeutic considerations are hydralazine, labetolol, calcium antagonists are useful; avoid sodium nitroprusside.
Intravenous Drugs for Hypertensive Emergencies Available In Indonesia
Vasodilators
- Clonidine
- Nitroglicerin
- Sodium nitropruside
Ca-Antagonist
- Diltiazem hydrochloride
Commonly Used Drug in Hypertensive Emergency
- Diltiazem intravenous (Herbesser): rapidly reduced blood pressure; useful for hypertensive emergency and urgency; acts as calcium slow channel blockers; dose-dependent with predictable onset of action; no rebound on withdrawn; the adverse effects are bradycardia, hypotension, headache, and flushing; has anti-ischemic and anti-arrhythmic effect (class-IV).
- Diltiazem injection: each ampoule of diltiazem injection should be dissolve in at least 5 millilitres aquadest or NaCl or glucose solution before use. The kinds of diltiazem-injection are:
§ Bolus intravenous injection: 0.20 – 0.35 mg/kg body weight; adult (50 kg): 1 ampoule (1 – 3 minutes)
§ Drip intravenous infusion (flat): 5 – 15 mcg/kg body weight/min; adult (50 kg): 15mg/hour – 45 mg/hour
§ Drip intravenous infusion (maintenance): 1 – 5 mcg/kg body weight/min; adult (50 kg): 5mg/hour – 15 mg/hour
- Clonidine intravenous: reduce peripheral sympathetic tone by central stimulation of alfa2 receptor; unpredictable onset of action; the adverse effect are sedation, dry mouth, constipation and a tendency to an overshoot or rebound hypertension on withdrawn.
- Nitrogliserin intravenous: strength vasodilator (arterial and venodilator); direct interacting with nitrate receptors on vascular smooth muscle; a rapid onset and duration of action; the adverse effects are headache, tachycardia, nausea, and vomiting.
Conclusion
- Hypertensive emergencies require immediate blood pressure reduction. This is most safely accomplished in the intensive care setting with use of an Intravenous agent.
- With the advent of better tolerated, long-acting anti hypertensive agents, hypertensive crisis become less common, with an estimated prevalence rate of 1 % among hypertensive patients.
- Diltiazem intravenous is scalable and predictable effective to lower blood pressure faster in avoiding complications of hypertensive emergency.
- In hypertensive urgencies blood pressure should be reduced more gradually with a fast-acting agent per o.s in an out patient setting.
Adapted from Lecture Note on Current Treatment of Hypertensive Emergencies by dr. Dhani Redhono, Sp.Pd
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