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Encephalopathy, Hypertensive: Treatment & Medication
Updated: Nov 17, 2009
- Overview
- Differential Diagnoses & Workup
- Treatment & Medication
- Follow-up
Treatment
Medical Care
In patients without hypertension, cerebral autoregulation preserves a relatively constant cerebral blood flow at a range of mean arterial blood pressures of 60-90 mm Hg. In chronically hypertensive patients, autoregulation is altered and shifted upward to maintain a relatively constant cerebral blood flow at a higher mean arterial blood pressure range.
- When initiating therapy, the baseline blood pressure must be considered to avoid excessive blood pressure lowering and prevent cerebral ischemia. Lowering the mean arterial pressure by 25% and the diastolic blood pressure to 100-110 mm Hg usually is a safe maneuver because of the pressure autoregulatory cerebral blood flow range.
- Acute monitoring in an intensive care unit with arterial blood pressure monitoring is required for adequate titration of pharmacologic agents and monitoring of end organ function.
Medication
Pharmacologic agents selected for use in hypertensive encephalopathy should have few or no CNS adverse effects. Avoid agents such as clonidine, reserpine, and methyldopa. Although the clinical impact has not been determined, diazoxide is avoided because of the impact of decreased cerebral blood flow. If neurological deterioration worsens with therapy, reconsider the extent of blood pressure lowering or consider alternate diagnoses.
Labetalol provides a steady consistent drop in blood pressure without compromising cerebral blood flow. Labetalol is frequently used as initial therapy. Because of nonselective beta-blocking properties, it should be avoided in severe reactive airways disease and cardiogenic shock.
Nitroglycerin has been used to provide a rapid reduction in blood pressure complicating myocardial ischemia. The reduction in blood pressure may be severe and can cause further complications due to venodilatory effects in volume-contracted individuals. Nitroprusside and hydralazine pose a theoretical risk of intracranial shunting of blood. Thus, these agents should be avoided in patients suspected of having increased intracranial pressure (ICP) because they may cause intracerebral shunting of blood, which increases ICP. An increasing number of authorities are considering labetalol, nifedipine, and esmolol as the preferred initial agent.
Trimethaphan camsylate is used to reduce the shearing force in the presence of aortic dissection. Hydralazine has a limited role, owing to reflex tachycardia, and it should not be used in patients with suspected coronary artery disease.
Antihypertensive Agent
These agents are used to reduce blood pressure.
Labetalol (Normodyne)
Competitive and selective alpha1-blocker and nonselective beta-blocker with predominantly beta effects at low doses. Onset of action is 5 min, with half-life of 5.5 h. Provides a steady, consistent drop in BP without compromising cerebral blood flow.
Adult
20 mg IV bolus, then 20-80 mg IV bolus q10min; not to exceed 300 mg; 2 mg/min IV infusion alternatively, titrate to desired BP; not to exceed 300 mg
Pediatric
Not established
Labetalol decreases the effect of diuretics and increases toxicity of methotrexate, lithium, and salicylates; may diminish reflex tachycardia resulting from nitroglycerin use without interfering with hypotensive effects; cimetidine may increase labetalol blood levels; glutethimide may decrease labetalol effects by inducing microsomal enzymes
Documented hypersensitivity; cardiogenic shock, bradycardia, atrioventricular block, uncompensated congestive heart failure; pulmonary edema, reactive airway disease
Pregnancy
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions
Caution in impaired hepatic function; discontinue therapy if signs of liver dysfunction are present; in elderly patients, a lower response rate and higher incidence of toxicity may be observed
Nicardipine (Cardene)
Calcium channel blocker. Potent rapid onset of action, ease of titration, and lack of toxic metabolites. Effective but limited reported experience in hypertensive encephalopathy.
Adult
Loading dose: 5-15 mg/h IV
Maintenance dose: 3-5 mg/h IV
Pediatric
Not established
H2 blockers may increase bioavailability of nicardipine; coadministration with propranolol or metoprolol may increase cardiac depressant effects on AV conduction
Documented hypersensitivity; severe hypotension; cardiogenic shock; atrial fibrillation; CHF
Pregnancy
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions
Adjust dose in hepatic and renal impairment; may increase frequency and duration of angina attacks
Esmolol (Brevibloc)
Ultra — short-acting agent that selectively blocks beta 1 receptors with little or no effect on beta 2 receptor types. Particularly useful in patients with elevated arterial pressure, especially if surgery is planned. Shown to reduce episodes of chest pain and clinical cardiac events compared with placebo. Can be discontinued abruptly if necessary.
Useful in patients at risk for experiencing complications from beta-blockade; particularly those with reactive airway disease, mild-moderate LV dysfunction, and/or peripheral vascular disease. Short half-life of 8 min allows for titration to desired effect and quick discontinuation if needed.
Adult
Loading dose: 250-500 mcg/kg infused over 1 min
Maintenance infusion: 50 mcg/kg/min over 4 min
If adequate effect not observed within 5 min, repeat loading dose and follow with maintenance infusion using increments of 50 mcg/kg/min (for 4 min); regimen may be repeated up to 4 times if necessary
As desired BP approached, skip loading infusion and reduce dose increments in maintenance infusion from 50 mcg/kg/min to 25 mcg/kg/min; may increase interval between titration steps from 5-10 min
Pediatric
Not established
Aluminum salts, barbiturates, NSAIDs, penicillins, calcium salts, cholestyramine, and rifampin may decrease bioavailability and plasma levels of esmolol, possibly resulting in decreased pharmacologic effect; cardiotoxicity of esmolol may increase when administered concurrently with sparfloxacin, astemizole, calcium channel blockers, quinidine, flecainide, and contraceptives; toxicity of esmolol increases when administered concurrently with digoxin, flecainide, acetaminophen, clonidine, epinephrine, nifedipine, prazosin, haloperidol, phenothiazines, and catecholamine-depleting agents
Documented hypersensitivity; uncompensated congestive heart failure, bradycardia, cardiogenic shock, and A-V conduction abnormalities
Pregnancy
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions
Beta-adrenergic blockers may mask signs and symptoms of acute hypoglycemia and clinical signs of hyperthyroidism; symptoms of hyperthyroidism, including thyroid storm may worsen when medication is abruptly withdrawn; withdraw drug slowly and monitor patient closely
Nitroprusside sodium (Nitropress)
Decreases systemic vascular resistance via direct dilatation of arterioles and veins. Should be avoided in patients suspected of having increased ICP. May cause intracerebral shunting of blood, increasing ICP.
Adult
0.5-1 mcg/kg/min IV infusion, titrate to desired BP
Pediatric
Not established
None reported
Documented hypersensitivity; idiopathic hypertrophic subaortic stenosis, atrial fibrillation or flutter
Pregnancy
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions
Potential for cyanide toxicity occurs with prolonged infusion (>72 h) and high infusion rate (>3 mcg/kg/min); suspect hyperreflexia, worsening mental status, and toxicity in the presence of metabolic acidosis; treatment for cyanide toxicity includes amyl nitrate, thiosulfate, and hydroxocobalamin; dialysis may be necessary for thiocyanate toxicity; hypoxia by inhibition of hypoxia-induced vasoconstriction in the pulmonary vasculature causes perfusion to nonventilated areas of the lung
Trimethaphan camsylate (Arfonad)
A ganglionic blocking agent primarily used in aortic dissection. Reduces heart rate and left ventricular ejection rate, thus lowering shearing force.
Adult
0.5-10 mg/min IV infusion, titrate to desired BP
Pediatric
Not established
Coadministration with anesthetic agents may cause hypotension; trimethaphan may potentiate neuromuscular blocking action of nondepolarizing agents and succinylcholine
Documented hypersensitivity; anemia; cerebral vascular disease; coronary artery disease; glaucoma; hypovolemia; MI; respiratory insufficiency; shock
Pregnancy
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions
Decreased cardiac output and peripheral vascular resistance may occur, causing orthostatic hypotension; ganglionic blockade causes dry mouth, visual changes, urinary retention, and ileus
Phentolamine (Regitine)
Alpha1- and alpha2-adrenergic blocking agent that blocks circulating epinephrine and norepinephrine action, reducing hypertension that results from catecholamine effects on the alpha receptors.
Adult
5-10 mg IV bolus
0.2-5 mg/min IV infusion
Pediatric
Not established
Concurrent administration of epinephrine or ephedrine may decrease phentolamine effects; ethanol increases phentolamine toxicity
Documented hypersensitivity; coronary or cerebral arteriosclerosis; renal impairment
Pregnancy
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions
Caution in tachycardia, peptic ulcer, and gastritis; cerebrovascular occlusions and myocardial infarctions can occur following phentolamine administration
Nitroglycerin (Nitro-Bid)
Provides arteriolar dilation and venodilation. Used in emergencies involving myocardial ischemia due to the dilatory effects of nitroglycerin on coronary arteries.
Adult
5-300 mcg/min IV infusion, titrate to desired BP
Pediatric
Not established
Aspirin may increase nitrate serum concentrations; marked symptomatic orthostatic hypotension may occur with coadministration of calcium channel blockers (dose adjustment of either agent may be necessary)
Documented hypersensitivity; severe anemia; shock; postural hypotension; head trauma, cerebral hemorrhage; closed-angle glaucoma
Pregnancy
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions
Caution in coronary artery disease and low systolic and diastolic blood pressure
Hydralazine (Hydrea)
Direct arteriolar dilator. Limited role because of reflex tachycardia causing increased cardiac oxygen demand. Should be avoided in patients suspected of having increased intracranial pressure.
Adult
5-20 mg IV bolus
0.5-1 mg/min IV infusion
Pediatric
Not established
MAOIs and beta-blockers may increase hydralazine toxicity; pharmacologic effects of hydralazine may be decreased by indomethacin
Documented hypersensitivity; mitral valve rheumatic heart disease
Pregnancy
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Precautions
Hydralazine has been implicated in MI; caution in suspected coronary artery disease
More on Encephalopathy, Hypertensive |
| Overview: Encephalopathy, Hypertensive |
| Differential Diagnoses & Workup: Encephalopathy, Hypertensive |
 Treatment & Medication: Encephalopathy, Hypertensive |
| Follow-up: Encephalopathy, Hypertensive |
| References |
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Further Reading
Keywords
hypertension, encephalopathy, hypertensive encephalopathy, hypertensive crisis, hypertensive emergency, hypertensive urgency, accelerated hypertension, malignant hypertension, arteriolar damage, necrosis, atherosclerosis
