Hypertensive emergency
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A '''hypertensive emergency''' is severe [[hypertension]] (high blood pressure) with acute impairment of an [[organ system]] (especially the [[central nervous system]], [[cardiovascular system]] and/or the [[renal system]]) and the possibility of [[irreversible]] organ-damage. In case of a hypertensive emergency, the [[blood pressure]] should be lowered aggressively over minutes to hours with an [[antihypertensive]] agent.
Several classes of antihypertensive agents are recommended and the choice for the antihypertensive agent depends on the cause for the hypertensive crisis, the severity of elevated blood pressure and the patients usual blood pressure before the hypertensive crisis. In most cases, the administration of an [[intravenous]] [[sodium nitroprusside]] [[Injection (medicine)|injection]] which has an almost immediate [[antihypertensive]] effect is suitable but in many cases not readily available. In less urgent cases, oral agents like [[captopril]], [[clonidine]], [[labetalol]], [[prazosin]], which have all a delayed onset of action by several minutes compared to sodium nitroprusside, can also be used.
It is also important that the blood pressure is lowered not too abruptly, but smoothly. The initial goal in hypertensive emergencies is to reduce the pressure by no more than 25% (within minutes to 1 or 2 hours) and then toward a level of 160/100 mm Hg within 2-6 hours. Excessive reductions in pressure may precipitate coronary, cerebral, or renal ischemia. <ref name=AMN>{{cite web | Brewster LM, MD; Michael Sutters, MD | title =Hypertensive Urgencies & Emergencies - Hypertension Drug Therapy | work =Systemic Hypertension | url=http://www.health.am/hypertension/hypertensive-urgencies-emergencies/ | year = 2006 | publsiher=Armenian Health Network, Health.am | accessdate=2007-12-02}}</ref>
The diagnosis of a hypertensive emergency is not only based on the absolute level of blood pressure, but also on the individual regular level of blood pressure before the hypertensive crisis. Individuals with a history of [[chronic (medicine)|chronic]] hypertension may not tolerate a "normal" blood pressure.
==Incidence==
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. <ref name=Cleveland>{{cite web | Vidt DG | title =Emergency room management of hypertensive urgencies and emergencies | work = | url=http://www.medscape.com/viewarticle/407727 | year = 2001 | publsiher=Cleveland Clinic Foundation | accessdate=2007-12-02}}</ref>
== Terminology ==
Generally, the terminology describing hypertensive emergencies can be confusing. Terms such as '''hypertensive crisis''', [[malignant hypertension]], '''hypertensive urgency''', [[accelerated hypertension]] and [[severe hypertension]] are all used in the literature and often overlap.
=== Hypertensive emergency as a specific term ===
The term hypertensive emergency is primarily used as a specific term for a hypertensive crisis with a diastolic blood pressure of 120 mm Hg and above plus end organ damage (brain, cardiovascular, renal) (as described above) in contrast to hypertensive urgency where as yet no end organ damage has developed. The former requires immediate lowering of blood pressure such as with sodium nitroprusside infusions (NOT injections) while urgencies (about 3/4 of cases with diastolic blood pressure of 120 mm Hg and above) can be treated with parenteral administration (NOT oral) of labetalol or some Ca-channel blockers. The former use of oral nifedipine, a Ca-channel antagonist, has been strongly discouraged or banned because it is not absorbed in a controlled and reproducible fashion and has led to serious and fatal hypotensive problems.
=== Hypertensive emergency as a generic term ===
Sometimes, although not very often, the term hypertensive emergency is also used as a generic term, comprising both hypertensive emergency as a specific term for a serious and urgent condition of elevated blood pressure and hypertensive urgency as a specific term of a less serious and less urgent condition (the terminology hypertensive crisis is usually used in this sense).
==References==
<references/>
== See also ==
* [[Malignant hypertension]]
* [[Hypertension]]
* [[Hypertensive retinopathy]]
[[Category:Cardiology]]
[[Category:Medical emergencies]]
[[de:Hypertensive Krise]]
[[uk:Гіпертензивний криз]]