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Query: UMLS:C0022116 (ischemia)
 91,303 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Hypertensive crisis is a life-threatening situation caused by acute elevation of blood pressure. The rise in blood pressure is very rapid and thus overwhelms protective adaptive mechanisms in the arterioles which occur under physiological conditions. Endothelial damage results. Focal vessel wall ischemia, inappropriate constriction and dilatation of arterioles, and increase in vascular permeability develop and cause functional disturbances of the heart, central nervous system or kidneys. Without immediate treatment, irreversible organ damage results due to ischemia and hemorrhage. The goal of therapy is to lower blood pressure by 25% within one hour. Blood pressure should be maintained at this level for 24 hours. Thereafter, blood pressure may be reduced by an additional 25% or to 180/100 mm Hg. Initial reduction in blood pressure by 55% may provoke irreversible end organ ischemia and infarction although blood pressure still may be well above the normal range. Most frequently, hypertensive crisis is treated with sodium nitroprusside as it allows controlled reduction in blood pressure due to its very rapid onset but short duration of action. Cyanide toxicity may develop in patients treated with high doses of sodium nitroprusside or with renal or kidney failure. Other agents used may have disadvantages such as unpredictable antihypertensive effects (calcium channel blockers, angiotensin converting enzyme inhibitor [ACEI]), tachycardia (calcium channel blockers, phentolamine, dihydralazine) or reduced renal blood flow (betablocker, ACEI).
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PMID:[Hypertensive crisis]. 849 71

Hypertensive crisis affects upward of 500,000 Americans each year. Although the incidence of hypertensive crisis is low, affecting fewer than 1% of hypertensive adults, more than 50 million adult Americans suffer from hypertension. Presentation of a patient with severe hypertension to the emergency room demands immediate evaluation, prompt recognition of a hypertensive emergency or urgency, and the prompt institution of appropriate therapeutic measures to prevent progression of target-organ damage and to avoid a catastrophic event. Hypertensive emergencies are severe elevations in blood pressure that are complicated by evidence of progressive target-organ dysfunction such as coronary ischemia, disordered cerebral function, a cerebrovascular event, pulmonary edema, or renal failure. Although therapy with parenteral antihypertensive agents may be initiated in the emergency department, these patients warrant prompt admission to an intensive care unit where continuous monitoring of blood pressure can be assured during therapy.
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PMID:Emergency room management of hypertensive urgencies and emergencies. 1141 1