#27 Vasopressors

Tina Vinsant, RN, host of the podcast Good Nurse Bad Nurse, joins us for a run through of all the major vasoactive agents given in the hospital. We minimized the jargon and maximized on practical cases, so join us for a memorable discussion of this fundamental subject.

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Phenylephrine

  • AKA: Neosynephrine, “Neo”
  • Pure α1 adrenergic agonist, increases SVR
  • Has no inotropic effect
  • What kind of patients do we see on this drip? Why?
    • Surgical patients being treated for anesthesia associated hypotension
    • Neurogenic shock, usually spinal cord injury
  • Notable SE: reflexive bradycardia
  • Drug interactions
    • MAOIs, tricyclic antidepressants, linezolid (enhanced HTN effect)
    • Acetaminophen: may increase serum concentration of phenylephrine
    • Fentanyl – may decrease serum concentration of Fentanyl; onset effect of fentanyl may be delayed

Norepinephrine

  • AKA: Levophed, “Levo”, Norepi
  • α1, α2, β adrenergic agonist. Used for multifactorial problems, like sepsis
  • Vasoconstriction effects greater than inotropic and chronotropic effects, but inotropic effects can help some with CO
  • Extravasation can cause ischemic tissue necrosis/sloughing (tx: phentolamine)
  • Notable SE: Decreased splanchnic and renal flow
  • Do not administer in same line as bicarb
  • Drug interactions
    • MAOIs, SSRI/SNRI, Linezolid, tricyclic antidepressants (may enhance hypertensive effect)

Epinephrine

  • AKA: Epi, Adrenalin
  • What kind of patients do we see on this drip? Why?
    • Anaphylaxis because it mimics our endogenous adrenalin
    • Adjunct to norepinephrine in septic shock
  • α1, α2, β1, β2 agonists: Increased SVR, inotropy and chronotropy
  • Notable SE: Can induce splanchnic (organs of the abdomen) flow, arrhythmia, Increases lactate levels and blood glucose

Dopamine

  • AKA: Dopa
  • Primary impact
    • Low dose: Increased inotropy and heart rate
    • Higher dose: Increased SVR and inotropy
  • Notable SE: Tachyarrhythmias
  • Drug interactions: MAOIs, Linezolid, SSRI/SNRI, tricyclic antidepressants (enhanced hypertensive effect)

Dobutamine

  • Positive lusitropic (myocardial relaxation), inotropic (contractility), & chronotropic (heart rate) effects
  • Tachyphylaxis w/ infusions > 72 hrs (diminishing effect of drug despite increasing dosage)
  • Can cause vasodilation
  • Minimal alpha effects
  • Decreases SVRIncreases CO
  • Most commonly used for severe HF and cardiogenic shock

Milrinone

  • What kind of patients do we see on this drip? Why?
    • Advanced HF
    • Bridge therapy
    • Palliative
  • Does not work on adrenergic receptors
  • Phosphodiesterase III inhibitor.  Phosphodiesterase III is present in the cardiac sarcoplasmic reticulum, smooth muscle in arteries and veins. 
  • Positive inotropy, positive lusitropy, and vasodilation
  • Similar to dobutamine with few SE

Vasopressin

  • This drug is not vasoactive drug – it increases BP by increasing blood volume
  • Vasopressin is indicated to increase blood pressure in adults in vasodilatory shock refractory to the application of fluids and catecholamines.

Midodrine

  • PO!
  • Midodrine is an alpha agonist and acts as a peripheral vasoconstrictor

Suggested Read

ALiEM: Choosing the right vasopressor agent in hypotension