Vasopressors and inotropes

From IDWiki

Receptors

  • Alpha-adrenergic receptors:
    • Alpha-1 agonists cause vasoconstriction
    • Alpha-2 agonists causes vasodilatation especially of coronary arteries
  • Beta-adrenergic receptors:
    • Beta-1 agonists increases HR and cardiac contractility --> increased CO
    • Beta-2 agonists dilate small coronary A's, visceral organ A's, skeletal muscle A's and increase bronchodilation
  • Dopaminergic receptors:
    • 7 types of dopamine receptors
    • D4 agonists increase cardiac contractility
    • D1 and D2 agonists increase renal diuresis and naturesis
  • Vasopressin receptors:
    • V1 agonists cause vasoconstriction mostly in peripheral arterioles and increased sensitivity to catecholamines
Pressor Alpha Beta-1 Beta-2 Notes
Dobutamine ++ + More of an inotrope, really.
Dopamine, moderate +++ +++ Precursor to norepi/epi. Higher risk of tachyarrhythmias than norepi.
Dopamine, high ++ +++ +++ More alpha with high doses.
Epinephrine +++ ++++ +++ Increases lactate.
Norepinephrine +++ +
Phenylephrine +++ Beware reflex bradycardia.
Vasopressin Acts on V1 receptors. Increase SVR and can cause ischemia.
Milrinone Phosphodiesterase III inhibitor. Avoid in renal failure. Long half-life.

Treatment Algorithms

  • Distributive shock: norepinephrine, then add vasopressin or epinephrine, then add dopamine or dobutamine
  • Cardiogenic shock
    • If left heart failure and BP can tolerate: Dobutamine
    • If right heart failure and BP can tolerate: Milrinone
  • Opioid-induced hypotension: phenylephrine