Surgical Critical Care: Vasopressor Pharmacology

Vasopressor Pharmacology

Comparison Chart

  α-1 α-2 β-1 β-2 D Effects
Midodrine X BP
Phenylephrine X BP
Norepinephrine X (Some) BP
Epinephrine High High Low Low Heart/Hypotension (Low) & BP (High)
Dopamine High High Med Med Low Renal (Low), Heart (Med) & BP (High)
Dobutamine X (Some) Heart
Isoproterenol X X Heart/Hypotension
Vasopressin BP
Angiotensin II BP
Milrinone Contractility & Pulmonary Vasodilation

Midodrine

  • Receptors: α-1
  • Effects: Increase BP
  • Given Orally, Often When Unable to Fully Wean from Other IV Vasopressors
  • General Dosing: 2.5-10 mg PO Every 8 Hours

Phenylephrine (Neo-Synephrine)

  • Receptors: α-1
  • Effects: Increase BP
  • General Dosing:
    • Weight Based: 0.1-1.5 mcg/kg/min
    • Non-Weight Based: 10-200 mcg/min
  • May Cause Baroreceptor-Mediated Reflex Bradycardia (Due to Sole Alpha Stimulation)

Norepinephrine (Levophed)

  • Receptors: α-1 & β-1 (Less Pronounced at Higher Doses)
  • Effects: Increases BP
    • Also Cause Splanchnic Vasoconstriction
  • General Dosing:
    • Weight Based: 0.05-2.0 mcg/kg/min
    • Non-Weight Based: 2-64 mcg/min

Epinephrine (Adrenaline)

  • Low-Dose (0.1-0.3 mcg/kg/min):
    • Receptors: β-1/2
    • Effects: Increased Contractility but May See Decreased BP
  • High-Dose (0.3-1.0 mcg/kg/min):
    • Receptors: α-1/2
    • Effects: Vasoconstriction & Increase BP

Dopamine

  • Low-Dose (1-2 mcg/kg/min):
    • Receptors: Dopamine Receptors
    • Effects: Splanchnic Vasodilation (“Renal Dose Dopamine”)
  • Medium-Dose (2-10 mcg/kg/min):
    • Receptors: β-1
    • Effects: Positive Inotropy
  • High-Dose (10-20 mcg/kg/min):
    • Receptors: α-1
    • Effects: Vasoconstriction & Increase BP

Dobutamine

  • Receptors: β-1 (Primarily) & Some β-2
  • Effects: Increased Contractility & Heart Rate
    • Can Cause Hypotension
  • General Dosing: 1-20 mcg/kg/min

Isoproterenol (Isoprenaline)

  • Receptors: β-1/2
  • Effects: Increased Contractility & Heart Rate
    • Blood Pressure May Decrease Due to Vasodilation
  • General Dosing: 2-10 mcg/min
  • May Cause Cardiac Arrhythmia and Ischemia

Arginine Vasopressin (AVP)

  • Receptors: V-1 (Primary Vasoactive Receptor)
    • May Also Affect V-2 & V-3
  • Effects: Vasoconstriction & Increase BP
  • General Dosing: 0.03-0.04 U/min
    • Dose is Not Titrated

Angiotensin II

  • Receptors: AT-1 & AT-2
    • Part of the RAAS System
  • Effects: Vasoconstriction & Increased BP
    • Also Activates Adrenal Cortex to Stimulate Aldosterone Secretion
    • Also Activates Hypothalamus to Stimulate Vasopressin Secretion
  • General Dosing: 5-80 ng/kg/min

Milrinone

  • PDE Inhibitor
  • Effects: Increase Contractility & Pulmonary Vasodilation
  • Good for Long-Term, Chronic CHF
  • General Dosing: 0.375-0.75 mcg/kg/min