GENERAL THERAPIES / HYPERTENSION

Hypertensive crisis

Created 03/11/2022, last revision 25/01/2023

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 following two terms
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)

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

cerebrovascular
- hypertensive encephalopathy (confusion, headaches, nausea/vomiting, visual disturbances, seizures)
  - symptoms of hypertensive encephalopathy resolve after blood pressure is lowered and autoregulation of cerebral flow 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

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 suspected, also measure BP in the lower limbs
look 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 neurological complaints/signs or case of head injury)
- chest x-ray (in patients with shortness of breath)
- CTA of the chest and abdomen for 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 urine metanephrines

arterial blood pressure (BP) monitoring is a mainstay of hemodynamic monitoring in neurocritical care
both hypotension and hypertension can impair vital organ function and worsen the outcome
BP monitoring techniques:
- non-invasive BP monitoring (more common)
  - intermittent (inflatable cuff) – the proper cuff size is critical
    - manual (auscultatory, palpatory)
    - automated (oscillometric)
  - continuous
    - volume clamp method
    - arterial applanation tonometry
- invasive BP measurement via arterial cannulation (most commonly automated)
choice of BP monitoring must be individualized
- low-risk patients – intermittent oscillometric BP monitoring
- high-risk, hemodynamically unstable patients – continuous BP monitoring (noninvasive or invasive)
- critically ill patients/hypertensive emergencies – continuous invasive BP monitoring via an arterial catheter is preferred

Proper cuff size

the cuff bladder length should be at least 80% of the upper arm circumference
- arm circumference < 35 cm – cuff 16×30 cm (suitable for most patients)
- arm circumference 35-44 cm – cuff 16×36 cm
- arm circumference > 45 cm – cuff 16×42 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 commonly occurs during the 3rd trimester of pregnancy and may occur before, during, or after delivery
eclampsia = elevated BP associated with seizures, multi-organ damage (aspiration pneumonia, cerebral hemorrhage, kidney failure, pulmonary edema, HELLP syndrome), and coagulopathy

The severity of a hypertensive crisis depends on:

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

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