Antihypertension Drugs for Emergency Hypertension

Understanding cerebral autoregulation provides a basis for treating a patient with emergency hypertension. Normally, cerebral autoregulation maintains a consistent blood flow to the brain and keeps cerebral perfusion pressure within normal limits despite variations in systemic arterial pressure. Normally, a mean arterial pressure (MAP) of 60 mm Hg is the lower limit at which cerebral autoregulation is effective. But in patients with chronic hypertension, the lower limit of effective autoregulation is a MAP of about 120 mm Hg. The upper limit of effective autoregulation is 160 mm Hg. And cerebral edema occurs when MAP is greater than 160 mm Hg.

So the goal of treatment for a patient with emergency hypertension is to lower MAP by 25% and to reduce diastolic blood pressure to 100 to 110 mm Hg over several hours, while maintaining cardiovascular, cerebral, retinal, and renal function . If the blood pressure drops too low or too quickly, the central nervous system's autoregulatory mechanism may not be able to respond fast enough. Cerebral perfusion may become inadequate, and emergency hypertension may be compounded by cerebral ischemia or a CVA. Further treatment should focus on slowly reducing the patient's blood pressure to a normal level over several days to several weeks.

However, if your patient has an aortic dissection, take steps to lower his blood pressure as quickly as possible to stop the progressive dissection. But remember that aggressive antihypertensive therapy is contraindicated for a patient with a cerebral infarction, intracerebral hemorrhage, or subarachnoid hemorrhage because of the risk of cerebral hypoperfusion.

Be Aware of these Facts

Assure your patient and his family that the prognosis is good after treatment for emergency hypertension. Reinforce the need for him to stay in the ICU to receive I.V. drugs and to have his blood pressure monitored continuously. And tell them that he'll be monitored constantly to reduce the risk of long-term organ damage.

After the crisis, teach the patient how to manage his blood pressure and reduce the risk of future episodes of emergency hypertension. Start with a review of lifestyle modifications. Obtain any necessary referrals to other health care professionals, such as a home care nurse, dietitian, or psychologist. And refer the patient to appropriate community resources, support groups, and educational programs.

The physician probably will prescribe antihypertensive drugs to control the patient's blood pressure after he leaves the hospital. So teach your patient the following:

name of each drug

prescribed dosage

relevant information about each drug, such as whether it should be taken with food

therapeutic effect of each drug

possible adverse effects of each drug

possible interactions with other drugs.

Warn the patient not to stop taking his antihypertensive drugs. Reducing his dosage even slightly could cause his blood pressure to rise, provoking a recurrence of emergency hypertension. So explain that because hypertension rarely causes symptoms, he should continue to take his drugs as prescribed-even when he feels well. Instruct him to report unpleasant adverse effects, such as GI distress, lethargy, and sexual dysfunction, to the physician, who may be able to eliminate them by prescribing a different drug or dosage. Also, tell the patient not to take other drugs, including nonprescription drugs, without his physician's permission.

Determine whether your patient can pay for his drugs. If not, consult with your facility's social services department about resources to assist in paying for his treatment.

Although diagnostic testing is performed throughout an episode of emergency hypertension, the full effects of the trauma may not be evident for several days or weeks. Instruct your patient to report any increase or decrease in his urine output. Also, tell him to report urine that is bloody or tea colored or contains white mucous threads. Tell him to notify his physician if he experiences any changes in vision, including cloudiness, blurred vision, or temporary blindness.

Instruct your patient to report any changes in neurologic or cardiovascular function and teach him the signs and symptoms of impaired function. Neurologic changes may include increased drowsiness, fatigue, confusion, forgetfulness, and difficulty waking from sleep. Cardiovascular changes may include palpitations, chest pain, swelling of the legs and feet, decreased tolerance to exercise, shortness of breath, dyspnea on exertion, productive cough, and pink-tinged frothy sputum.

Before your patient is discharged, inform him that he'll need frequent blood pressure monitoring and physical examinations by his physician and that his drug dosage may have to be adjusted. Periodically, he also may be asked for urine and blood specimens for laboratory tests and may have to undergo diagnostic testing to monitor his organ functions. Confirm that he knows the date and time of his follow-up appointment with his physician.

Teach him and his family the basics of home blood pressure monitoring. If a home care nurse will be visiting him after discharge, let him know that she'll routinely monitor his blood pressure and review the readings he has recorded between her visits. She'll monitor his compliance, make sure he takes his antihypertensive drugs properly, reinforce and support his lifestyle modifications, and regularly assess his organ functioning. The home care nurse also will reevaluate his plan of care to determine whether its goals are being met.

Article Written By Robert Baird, author for www.hypertensionblog.org/. Find useful medication for the treatment of hypertension available at our site.

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