UMEM Educational Pearls

Title: Back 2 Basic Series: Under Pressure - Vasopressors Part I

Posted: 9/2/2014 by Haney Mallemat, MD (Updated: 10/1/2014)
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Vasopressors are used in shock-states to increase mean arterial pressure (MAP) and improve distal tissue perfusion. Additionally, some agents have effects on the heart to augment cardiac output.

Receptors that vasopressors work on include:

Alpha-1: increase arterial tone (increases MAP) and venous tone to reduce venous pooling and augment cardiac preload
Beta-1: increase inotropy and chronotropy on heart muscle; also increases arterial tone
Beta-2 and Dopamine: cause vasodilation but may actually be beneficial because this increases perfusion to cardiac, renal, and GI tissues.
V1: arterial vasoconstriction to increase MAP
The chart below is a summary; please note that quoted receptor effects vary depending on the source reviewed

Norepinephrine (NE): excellent vasopressor for most types of shock and recommended as a first-line agent in the Surviving Sepsis Guidelines.

Works on alpha-1, beta-1, and beta-2 receptors.
Initial dosing 0.05 mcg/kg/min with a maximum dose often cited as 0.5 mcg/kg/min (though there is technically no maximum dose).

Epinephrine (a.k.a. Adrenaline): in several countries the first-line agent for shock (including sepsis).

Works similarly to NE on alpha-1, beta-1 and beta-2; it is a more potent inotrope than NE.
One downside is the production of lactic acid, which can sometimes lead to confusion when following serial lactates during resuscitation.

References

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