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Resident Survival Guide |
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Aarti Narayan, M.B.B.S [2]
Synonyms and keywords: Hypertensive emergency; hypertensive urgency; severe hypertension
Overview
Hypertensive crisis is a term used to describe a severe elevation in the blood pressure which may or may not be associated with end-organ damage.[1] Noncompliance with antihypertensive medications is the most common cause of hypertensive crisis.[2] Hypertensive crisis includes both hypertensive emergency and hypertensive urgency. Hypertensive urgency is the severe elevation in the blood pressure without any evidence of acute end-organ damage. Hypertensive emergency mostly falls into stage 2 of hypertension. It is usually the severe elevation in the blood pressure (systolic blood pressure >180 mm Hg, or diastolic blood pressure >120 mm Hg) complicated by acute end-organ dysfunction, such as hypertensive encephalopathy, eclampsia, dissecting aortic aneurysm, acute left ventricular failure with pulmonary edema, acute myocardial infarction, acute renal failure, or symptomatic microangiopathic hemolytic anemia.[3] The treamtnet of hyperetensive urgency requires a gradual reduction in blood pressure over 24 to 48 hours. In hypertensive emergency, the treatment should be targeted to reduce the blood pressure by not more than 25% within the first hour; when blood pressure is stable, it should be reduced to 160/100-110 mmHg within the next 2 to 6 hours.[3]
Causes
Life Threatening Causes
Hypertensive crisis is a life-threatening condition and must be treated as such irrespective of the cause.
Common Causes
- Antihypertensive medications withdrawal ( beta blockers, clonidine)
- Noncompliance with antihypertensive medications[2]
- Pheochromocytoma
- Side effects of monoamine oxidase inhibitors
- Stimulants (cocaine, methamphetamine, phencyclidine)
Treatment
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 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 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 hypertension may not tolerate a "normal" blood pressure.
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 calcium channel blockers. The former use of oral nifedipine, a calcium 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
- ↑ "The fifth report of the Joint National Committee on Detection, Evaluation, and Treatment of High Blood Pressure (JNC V)". Arch Intern Med. 153 (2): 154–83. 1993. PMID 8422206. Unknown parameter
|month=ignored (help) - ↑ 2.0 2.1 Stewart, DL.; Feinstein, SE.; Colgan, R. (2006). "Hypertensive urgencies and emergencies". Prim Care. 33 (3): 613–23, v. doi:10.1016/j.pop.2006.06.001. PMID 17088151. Unknown parameter
|month=ignored (help) - ↑ 3.0 3.1 Chobanian AV, Bakris GL, Black HR, Cushman WC, Green LA, Izzo JL; et al. (2003). "The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure: the JNC 7 report". JAMA. 289 (19): 2560–72. doi:10.1001/jama.289.19.2560. PMID 12748199.