GENERAL THERAPIES / HYPERTENSION

Hypertensive crisis

Created 03/11/2022, last revision 14/11/2022

Definition

  • a hypertensive crisis is a medical emergency characterized by a sudden and severe elevation in blood pressure
    • the levels of hypertension are not universally established and are arbitrary (usually > 180/120 mmHg)
    • the rate of BP elevation seems more important than its absolute value
    • the term crisis gets abandoned in favor of the two terms below
  • the presence of a target-organ lesion distinguishes:
    • hypertensive urgency – without target-organs damage
    • hypertensive emergency – with acute target-organs complications (heart, kidneys, brain, eyes)
  • hypertensive emergency has a mortality rate of up to 7% (Katz, 2009)

Etiology

  • decompensation of chronic hypertension
    • most commonly caused by sudden discontinuation of antihypertensive medication or drug interactions
    • perioperative
    • acute stroke (which can be a cause or a consequence of uncontrolled hypertension)
  • secondary hypertension
    • pheochromocytoma
    • preeclampsia/eclampsia
    • abuse of sympathomimetic drugs (amphetamine, LSD, cocaine)

Clinical presentation

  • cerebrovascular
    • hypertensive encephalopathy (confusion, headaches, nausea/vomiting, visual disturbances, seizures)
      • symptoms of hypertensive encephalopathy resolve after blood pressure is reduced and cerebral flow autoregulation is restored
    • posterior reversible encephalopathy syndrome (PRES)
    • intracerebral hemorrhage (focal symptoms)
    • subarachnoid hemorrhage (headache, meningeal syndrome)
  • cardiovascular (chest pain, shortness of breath)
    • acute left-sided heart failure (dyspnea, pulmonary edema)
    • acute MI/unstable AP
    • acute aortic dissection (acute and severe chest or back pain)
  • renal
    • acute renal failure
  • eye symptoms
    • hemorrhages, exudates, or edema of the papillae (signs of hypertensive retinopathy grade III or IV) are associated with hypertensive encephalopathy

Diagnostic evaluation

  • repeated BP measurement or continuous BP monitoring
    • start by measuring both arms’ blood pressure (aortic dissection or coarctation, subclavian artery stenosis)
    • if aortic dissection is being considered, measure BP in the lower limbs as well
  • search for organ damage
    • blood samples
      • CBC + coagulation
      • renal and hepatic tests
      • NT-proBNP (heart failure)
      • cardiac enzymes (in suspected ACS)
      • urine chemistry and urine sediment examination
      • D-dimers (when aortic dissection is suspected)
    • ECG
    • brain CT + CTA (in patients with acute neurologic complaints/signs or case of head injury)
    • chest x-ray (in patients with shortness of breath)
    • CTA of the chest and abdomen in suspected aortic dissection
    • fundoscopic exam (ophthalmoscopy)
  • exclude secondary hypertension
    • CT/MR angiography of renal arteries (renovascular hypertension)
    • plasma renin activity (PRA) and aldosterone, plasma or urinary metanephrines
  • arterial blood pressure (BP) monitoring is a mainstay of hemodynamic monitoring in neurocritical care
  • both hypotension and hypertension can impair the function of vital organs and worsen the outcome
  • BP monitoring techniques:
    • non-invasive BP measurement (more common)
      • intermittent (inflatable cuff) – the correct size of the cuff is crucial
        • manual (auscultatory, palpatory)
        • automated
      • continuous
        • volume clamp method
        • arterial applanation tonometry
    • invasive BP measurement via arterial cannulation (most commonly automated)
  • choice of blood pressure monitoring needs to be individualized
    • low-risk patients – intermittent oscillometric BP measurement
    • high-risk, hemodynamically unstable patients – continuous BP measurement (non-invasive or invasive)
    • critically ill patients/hypertensive emergency – continuous invasive BP monitoring via an arterial catheter is preferred

Proper cuff size

  • arm circumference < 33 cm: usually cuff 12 cm
  • arm circumference 33-41 cm: cuff 15 cm
  • arm circumference > 41 cm: cuff 18 cm
  • preeclampsia = new onset hypertension >140/90 mmHg + proteinuria > 500 mg/24 h or 300 mg/l occurring after 20 weeks gestation or during the second half of pregnancy
    • most often, it occurs during the 3rd trimester of pregnancy and may occur before, during, or after delivery
  • eclampsia = elevation of BP is accompanied by seizures, multi-organ damage (aspiration pneumonia, cerebral hemorrhage, kidney failure, pulmonary edema, HELLP syndrome), and coagulopathy

Classification

The severity of a hypertensive crisis depends on:

  • current BP values
  • presence of acute target-organ damage
  • the rate of BP increase (how long it took for BP to increase from the baseline values to the current values)
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Management of hypertensive emergency

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