Hypertensive crisis
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.  Noncompliance with antihypertensive medications is the most common cause of hypertensive crisis.  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.  The treatment of hypertensive 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.

# Classification
Hypertensive crisis can be further classified as hypertensive urgency and hypertensive emergency based on either the absence or presence of acute end-organ damage.

## Hypertensive Urgency
Hypertensive urgency is an acute severe elevation in the blood pressure without any evidence of acute end-organ damage.

## Hypertensive Emergency
Hypertensive emergency mostly falls into stage 2 of hypertension (systolic blood pressure greater >160 mm Hg or diastolic blood pressure >100 mm Hg).  It is usually an acute 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.

### 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).

# 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
- Pheochromocytoma
- Side effects of monoamine oxidase inhibitors
- Stimulants (cocaine, methamphetamine, phencyclidine)
- Phenylephrine

## Causes by Organ System

## Causes in Alphabetical Order

# Treatment
Management is directed by clinical practice guidelines:
- "Hypertensive emergencies are defined as severe elevations in BP (>180/120 mm Hg) associated with evidence of new or worsening target organ damage."
- "hypertensive urgencies are situations associated with severe BP elevation in otherwise stable patients without acute or impending change in target organ damage or dysfunction....Reinstitution or intensification of antihypertensive drug therapy and treatment of anxiety as applicable. There is no indication for referral to the emergency department, immediate reduction in BP in the emergency department, or hospitalization for such patients"

## Provide acute therapy for hypertensive emergency
For patients with end-organ damage and SBP >179 and DBP >119, the patient is suffering from hypertensive emergency. These patients should be admitted to the ICU and receive parenteral antihypertensive medications to avoid fluctuating drug levels from the oral or intramuscular routes.  The immediate goal is to decrease the DBP by 10-15 % or to approximately 110 mm Hg in the first 30-60 minutes, then when blood pressure is stable, reduce to 160/100-110 mmHg within the next 2-6 hours. Start the treatment with short-acting IV antihypertensive drugs depending on the type of the end-organ damage. Keep close monitoring to the blood pressure and in severely ill patients intra-arterial blood pressure monitoring is used. Once the blood pressure is stable we shift to oral antihypertensive drugs. When the patient is stable and the blood pressure is well tolerated, reduce the blood pressure to normal within 24-48 hours.

## Increase chronic therapy for hypertensive urgency
Another option is no acute treatment but initiate chronic treatment
Intensifying treatment of hospitalized patients in the absence of emergency may worse outcomes, at least for noncardiac patients. However, one study found better outcomes when treated. The prevalence of end-organ damage was not clear in this study.

## Intravenous Antihypertensive Drugs
Shown below is a table of the IV antihypertensive drugs and their appropriate doses.

## Oral Antihypertensive Drugs
Shown below is a table of the oral antihypertensive drugs and their appropriate doses.
- Other agents to consider include:
- PO frusemide 20mg (repeat as necessary)
- PO nifedipine SR 30mg, single dose
- PO felodipine 5 mg, single dose

## Management of Specific Hypertensive Emergencies