Hypertensive emergency

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Malignant hypertension
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Hypertensive emergency
Other namesMalignant hypertension, hypertensive crises
CT scan depicting intracranial hemorrhage, a possible complication of hypertensive emergency. Patients with spontaneous intracranial hemorrhage present with newfound headache and neurologic deficits.
SpecialtyCardiology

A hypertensive emergency is very

cutoff values.[1][2][3]

Signs and symptoms

Fundoscopic view of an eye with diabetic retinopathy. Similar to hypertensive retinopathy, evidence of nerve fiber infarcts due to ischemia (cotton-wool spots) can be seen on physical exam.

Symptoms may include headache,

acute kidney failure. People can have decreased urine production, fluid retention, and confusion.[citation needed
]

Other signs and symptoms can include:[citation needed]

The most common presentations of hypertensive emergencies are

congestive heart failure (12%).[4] Less common presentations include intracranial bleeding, aortic dissection, and pre-eclampsia or eclampsia.[5]

Massive, rapid elevations in blood pressure can trigger any of these symptoms, and warrant further work-up by physicians. Physical exam would include measurement of blood pressure in both arms. Laboratory tests to be conducted include urine toxicology, blood glucose, a basic metabolic panel evaluating kidney function, or a complete metabolic panel evaluating liver function, EKG, chest x-rays, and pregnancy screening.[6]

The eyes may show

bleeding in the retina, an exudate, cotton-wool spots, scattered splinter hemorrhages, or swelling of the optic disc called papilledema.[citation needed
]

Causes

Many factors and causes are contributory in hypertensive crises. The most common cause is patients with diagnosed, chronic hypertension who have discontinued anti hypertensive medications.[7]

Other common causes of hypertensive crises are autonomic hyperactivity such as

preeclampsia and eclampsia, hyperthyroidism and renovascular hypertension.[6][7] People withdrawing from medications such as clonidine or beta-blockers have been frequently found to develop hypertensive crises.[8] It is important to note that these conditions exist outside of hypertensive emergency, in that patients diagnosed with these conditions are at increased risk of hypertensive emergencies or end organ failure.[citation needed
]

Pathophysiology

Kidney Biopsy showing thrombotic microangiopathy, a histomorphologic finding seen in malignant hypertension

The pathophysiology of hypertensive emergency is not well understood. Failure of normal autoregulation and an abrupt rise in systemic vascular resistance are typical initial components of the disease process.[5]

Hypertensive emergency pathophysiology includes:[citation needed]

The resulting

multi-organ failure (failure of at least 3 organ systems) in about 3% of patients.[citation needed
]

In the brain,

blood flow. People with chronic hypertension can tolerate higher arterial pressure before their autoregulation system is disrupted. Hypertensives also have an increased cerebrovascular resistance which puts them at greater risk of developing cerebral ischemia if the blood flow decreases into a normotensive range. On the other hand, sudden or rapid rises in blood pressure may cause hyperperfusion and increased cerebral blood flow, causing increased intracranial pressure and cerebral edema, with increased risk of intracranial bleeding.[6]

In the heart, increased

systolic blood pressure, and widened pulse pressures, all resulting from chronic hypertension, can cause significant damage. Coronary perfusion pressures are decreased by these factors, which also increase myocardial oxygen consumption, possibly leading to left ventricular hypertrophy. As the left ventricle becomes unable to compensate for an acute rise in systemic vascular resistance, left ventricular failure and pulmonary edema or myocardial ischemia may occur.[5]

In the kidneys, chronic hypertension has a great impact on the kidney vasculature, leading to pathologic changes in the small arteries of the kidney. Affected arteries develop endothelial dysfunction and impairment of normal vasodilation, which alter kidney autoregulation. When the kidneys' autoregulatory system is disrupted, the intraglomerular pressure starts to vary directly with the systemic arterial pressure, thus offering no protection to the kidney during blood pressure fluctuations. The renin-aldosterone-angiotensin system can be activated, leading to further vasoconstriction and damage. During a hypertensive crisis, this can lead to acute kidney ischemia, with hypoperfusion, involvement of other organs, and subsequent dysfunction. After an acute event, this endothelial dysfunction has persisted for years.[5]

Diagnosis

The term hypertensive emergency is primarily used as a specific term for a hypertensive crisis with a diastolic blood pressure greater than or equal to 120 mmHg or systolic blood pressure greater than or equal to 180 mmHg.[9] Hypertensive emergency differs from hypertensive urgency in that, in the former, there is evidence of acute organ damage.[9] Both of these definitions had collectively been known as malignant hypertension, although this medical term is replaced.[citation needed]

In the pregnant patient, the definition of hypertensive emergency (likely secondary to pre-eclampsia or eclampsia) is only a blood pressure exceeding 160 mmHg systolic blood pressure or 110 mmHg diastolic blood pressure.[10]

Treatment

In a hypertensive emergency, treatment should first be to stabilize the patient's airway, breathing, and circulation per

antihypertensive agent. Documented goals for blood pressure include a reduction in the mean arterial pressure by less than or equal to 25% within the first 8 hours of emergency.[6] If blood pressure is lowered aggressively, patients are at increased risk of complications including stroke, blindness, or kidney failure.[5] Several classes of anti hypertensive agents are recommended, with the choice depending on the cause of the hypertensive crisis, the severity of the elevation in blood pressure, and the patient's baseline blood pressure prior to a hypertensive emergency. Physicians will attempt to identify a cause of the patient's hypertension, including chest radiograph, serum laboratory studies evaluating kidney function, urinalysis, as that will alter the treatment approach for a more patient-directed regimen.[citation needed
]

Hypertensive emergencies differ from hypertensive urgency in that they are treated parenterally, whereas in urgency it is recommended to use oral anti hypertensives to reduce the risk of hypotensive complications or ischemia.[5] Parenteral agents are classified into beta-blockers, calcium channel blockers, systemic vasodilators, or other (fenoldopam, phentolamine, clonidine). Medications include labetalol, nicardipine, hydralazine, sodium nitroprusside, esmolol, nifedipine, minoxidil, isradipine, clonidine, and chlorpromazine. These medications work through a variety of mechanisms. Labetalol is a beta-blocker with mild alpha antagonism, decreasing the ability of catecholamine activity to increase systemic vascular resistance, while also decreasing heart rate and myocardial oxygen demand. Nicardipine, Nifedipine, and Isradipine are calcium channel blockers that work to decrease systemic vascular resistance and subsequently lower blood pressure. Hydralazine and Sodium nitroprusside are systemic vasodilators, thereby reducing afterload, however can be found to have reflex tachycardia, making them likely second or third line choices. Sodium nitroprusside was previously the first-line choice due to its rapid onset, although now it is less commonly used due to side effects, drastic drops in blood pressure, and cyanide toxicity. Sodium nitroprusside is also contraindicated in patients with myocardial infarction, due to coronary steal.[8] It is again important that the blood pressure is lowered slowly. The initial goal in hypertensive emergencies is to reduce the pressure by no more than 25% the mean arterial pressure. Excessive reduction in blood pressure can precipitate coronary, cerebral, or kidney ischemia and, possibly, infarction.[citation needed]

A hypertensive emergency is not based solely on an absolute level of blood pressure, but also on a patient's baseline blood pressure before the hypertensive crisis occurs. Individuals with a history of

chronic hypertension may not tolerate a "normal" blood pressure, and can therefore present symptomatically with hypotension, including fatigue, light-headedness, nausea, vomiting, or syncope.[citation needed
]

Blood pressure targets[6]
<1 hr 25% reduction in the mean arterial pressure, diastolic blood pressure above 100
2-6 hr Systolic BP < 160 mmHg or Diastolic BP <110 mmHg
6-24 hr monitor BP targets, ensure non-rapid drop in BPs below 160 SBP or 100 DBP
1-2 d if no end-organ damage, monitor out-patient and JNC8 Guidelines for maintaining BP control

Prognosis

Severe hypertension is a serious and potentially life-threatening medical condition. It is estimated that people who do not receive appropriate treatment only live an average of about three years after the event.[10]

The

morbidity and mortality of hypertensive emergencies depend on the extent of end-organ dysfunction at the time of presentation and the degree to which blood pressure is controlled afterward. With good blood pressure control and medication compliance, the 5-year survival rate of patients with hypertensive crises approaches 55%.[1]

The risks of developing a life-threatening disease affecting the heart or brain increase as the blood flow increases. Commonly, ischemic heart attack and stroke are the causes that lead to death in patients with severe hypertension. It is estimated that for every 20 mm Hg systolic or 10 mm Hg diastolic increase in blood pressures above 115/75 mm Hg, the mortality rate for both ischemic heart disease, cancer and stroke doubles.[citation needed]

Consequences of hypertensive emergency result after prolonged elevations in blood pressure and associated end-organ dysfunction. Acute end-organ damage may occur, affecting the neurological, cardiovascular, kidney, or other organ systems. Some examples of neurological damage include

brain cancer, leukemia and microangiopathic hemolytic anemia.[citation needed
]

Epidemiology

In 2000, it was estimated that 1 billion people worldwide have hypertension, making it the most prevalent condition in the world.[4] Approximately 60 million Americans have chronic hypertension, with 1% of these individuals having an episode of hypertensive urgency. In emergency departments and clinics around the U.S., the prevalence of hypertensive urgency is suspected to be between 3-5%.[8] 25% of hypertensive crises have been found to be hypertensive emergency versus urgency when presenting to the ER.[10]

Risk factors for hypertensive emergency include age, obesity, noncompliance to anti hypertensive medications, female sex, Caucasian race, preexisting diabetes or coronary artery disease, mental illness, and sedentary lifestyle.

elderly, it may occur in children (though very rarely), likely due to metabolic or hormonal dysfunction. In 2014, a systematic review identified women as having slightly higher increased risks of developing hypertensive crises than do men.[4]

With the usage of anti hypertensives, the rates of hypertensive emergencies has declined from 7% to 1% of patients with hypertensive urgency.[4]

16% of patients presenting with hypertensive emergency can have no known history of hypertension.[5]

See also

References

  1. ^
    PMID 21998228
    .
  2. PMID 30165588
    .
  3. PMID 30020723
    .
  4. ^
    PMID 25598731
    . A summary of recommendations from the selected guidelines is presented in Table 2.
  5. ^
    OCLC 915775025.{{cite book}}: CS1 maint: location missing publisher (link
    )
  6. ^
    OCLC 1029074059.{{cite book}}: CS1 maint: location missing publisher (link
    )
  7. ^
    PMID 20395943
    .
  8. ^
    PMID 29340938
    .
  9. ^
    PMID 29133356
    .
  10. ^
    OCLC 989157341.{{cite book}}: CS1 maint: location missing publisher (link
    )
  11. PMID 14283119
    .

External links

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