Hypertensive Emergencies

Basics

Description

  • Hypertensive crisis:
    • Severely elevated BP defined by an SBP ≥180/120 mm Hg or a DBP >109 mm Hg
  • Hypertensive emergency:
    • Severely elevated BP associated with acute end-organ damage
    • No set cut-offs, typically SBP ≥180/120 mm Hg or DBP ≥110 mm Hg
  • Severe hypertension:
    • Traditionally defined as acute severe hypertension in the absence of acute target-organ damage
  • Loss of autoregulation of blood flow in hypertensive emergency:
    • Arterioles vasoconstrict to counter pressure
    • High pressures overwhelm arterioles and endothelial damage occurs
  • Endothelial injury leads to increased permeability, activation of the coagulation cascade and platelets, and deposition of fibrin
  • Activation of the renin–angiotensin system and the sympathetic nervous system:
    • Leads to further vasoconstriction and production of proinflammatory cytokines
  • End-organ ischemia:
    • Renewed release of vasoconstrictors
    • Worsened by pressure natriuresis
    • Triggers a vicious cycle
  • Organs affected:
    • Brain (encephalopathy, CVA, ICH)
    • Retina (hemorrhage, papilledema)
    • Heart (MI, aortic dissection, acute HF)
    • Kidneys (acute renal failure)
    • Placenta (preeclampsia/eclampsia)

Etiology

  • Essential HTN
  • Renal:
    • Vascular disease
    • Parenchymal disease
  • Coarctation of the aorta
  • CNS disorders:
    • Head trauma
    • CVA/ICH
    • Brain tumor
    • Spinal cord injury
  • Endocrine:
    • Pheochromocytoma
    • Cushing syndrome
    • Primary hyperaldosteronism
    • Renin-secreting tumor
  • Drugs:
    • Antihypertensive medication withdrawal
    • Caffeine, cocaine, phencyclidine, amphetamines
    • Erythropoietin, tacrolimus, cyclosporine, corticosteroids, oral contraceptives
    • MAOI interactions lead to intoxication
  • Autonomic hyperreactivity:
    • Guillain–Barré syndrome
    • Acute intermittent porphyria
  • Postop pain and/or anesthesia complications
  • Pregnancy related:
    • Preeclampsia/eclampsia

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