Hypertensive emergency and urgence

Abstract

DEFINITION, PATHOPHYSIOLOGY, THERAPY: The hypertensive crisis is characterized by a massive, acute rise in blood pressure. Patients with underlying hypertensive disease usually have an increase in systolic blood pressure values > 220 mmHg and diastolic values > 120 mmHg. The severity of the condition, however, is not determined by the absolute blood pressure level but by the magnitude of the acute increase in blood pressure. Thus, in the presence of primarily normotensive baseline values (such as those in eclampsia), even a systolic blood pressure > 170 mmHg may lead to a life-threatening condition. The most important causes are non-compliance (reduction or interruption of therapy), inadequate therapy, endocrine disease, renal (vessel) disease, pregnancy and intoxication (drugs). The management of this condition greatly depends on whether the patient has a hypertensive crisis with organ manifestation (hypertensive emergency) or a crisis without organ manifestation (hypertensive urgency). By documenting the medical history, the medical status and by simple diagnostic procedures, the differential diagnosis can be established at the emergency site within a very short period of time. In the absence of organ manifestations (hypertensive urgency) the patient may have non-specific symptoms such as palpitations, headache, malaise and a general feeling of illness in addition to the increase in blood pressure. In a hypertensive urgency the patient's blood pressure should not be reduced within a few minutes but within a period of 24 to 48 hours. Such adjustment can be achieved on an out-patient basis, however, only if the patient can be followed up adequately for early detection of a renewed attack. In the absence of follow-up facilities, the patient's blood pressure should be reduced over a period of 4 to 6 hours, if necessary in an out-patient emergency service. While intravenous medication is given preference when a rapid effect is desired, oral medication may be used for gradual reduction on an out-patient basis, depending on the patient's medical history and on any underlying chronic disease. Organ manifestations in the course of a hypertensive emergency concern the cardiovascular system and are associated with the symptoms of acute left-ventricular heart failure, the acute coronary syndrome or acute aortic dissection. In the brain the patient may have symptoms of hypertensive encephalopathy, hemorrhage, ischemia; in the kidney he/she may develop acute failure. The patient's blood pressure should be reduced rapidly during the treatment. It should not be reduced to the normal value, but by approximately 20-30% of the baseline value. The reason for a stepwise reduction in blood pressure is the fact that patients with chronic hypertension have an altered autoregulation curve. Acute normotension would lead to hypoperfusion in these patients. Those with aortic dissection or pulmonary edema are excepted from the rule of gradual blood pressure reduction. In the presence of these diseases, blood pressure must be reduced rapidly to normal values. Patients with a hypertensive emergency should always be admitted to the hospital. Parenteral treatment is given preference, since the effect of the treatment is rapid and occurs within a calculable period of time. Thus, parenteral treatment can also be better regulated than medication administered orally or by the sublingual route. Several antihypertensives are available for this purpose. The selection of the substance greatly depends on the existing organ failure as well as the reliable effectiveness and the regulability of the applied antihypertensive.