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Choosing Vasoactive Medications in the Postoperative Cardiac Surgery Patient

Posted by Liza Szelkowski, PA-C on Jul 19, 2016 9:21:24 AM

A patient enters the ICU after a redo repair of ascending aortic aneurysm, and total arch replacement.  He is in cardiogenic shock with unstable hemodynamics.  Another patient has been doing well after a straight forward aortic valve replacement, and has been on no vasoactive medications, but has become increasingly pale and cold.  Urine output is down, but he is hypertensive.  A third patient arrested on the step down unit, and was resuscitated.  She transfers to your ICU and needs to be stabilized.   First line therapy for all of these patients will be vasoactive medications.  Unfortunately, choosing the best fit for each patient is not always straight forward.

Clinicians new to cardiac critical care might be dismayed to find that there is no magic formula for choosing vasoactive medications.  In fact, a study of the literature will show that there is no one combination of drugs that decreases complications, or improves outcomes.  There is, however, a formula for success.  First, study and become familiar with the hemodynamic profiles of commonly used drugs.  Next, evaluate the hemodynamic profile of the patient in question.  Finally, apply the drug, or drug combination, that fits the patient’s clinical scenario.

For example, for a patient with low cardiac output, and low SVR, milrinone may not be the best choice.  Epinephrine would be a better inotrope for this patient.  However, if the same patient had a heart rate in the 120s, that would make epinephrine less of a practical choice because it is a positive chronotrope as well.  In this case, a combination of milrinone and phenylephrine, or vasopressin, would be a better choice.  In another example, a patient with low cardiac output and low heart rate, but adequate blood pressure, may be well served with Dobutamine because it is a positive inotrope and chronotrope. 

Although each patient is different, and the choices of drugs may be overwhelming, matching the hemodynamic profile of vasoactive medications with the clinical scenario of the patient provides the clinician with a basis to stabilize, and effectively treat, the many different types of patients seen in cardiac surgery.

HEMODYNAMIC PROFILES OF INOTROPES AND VASOPRESSORS USED IN THE CARDIAC ICU

DOPAMINE

VARIABLE EFFECT ON SVR, CHRONOTROPY INCREASES WITH DOSE, POSITIVE INOTROPE,  CAN INCREASE OR DECREASE MAP DEPENDING ON DOSE

DOBUTAMINE

DECREASES SVR, STRONG CHRONOTROPE, POSITIVE INOTROPE, VARIABLE EFFECT ON MAP DEPENDING ON DOSE

EPINEPHRINE

VARIABLE EFFECT ON SVR, MODERATE CHRONOTROPE, POSITIVE INOTROPE, MODERATE VASOPRESSOR

MILRINONE

DECREASES SVR, WEAK CHRONOTROPE, POSITIVE INOTROPE, VASODILATOR

ISOPROTERENOL

DECREASES SVR, VERY STRONG CHRONOTROPE, POSITIVE INOTROPE, CAN INCREASE OR DECREASE MAP DEPENDING ON DOSE

NOREPINEPHRINE

INCREASES SVR, MODERATE CHRONOTROPE, POSITIVE INOTROPE, STONG VASOPRESSOR

PHENYLEPHRINE

INCREASES SVR, NO EFFECT ON HEART RATE, NO EFFECT ON CARDIAC OUTPUT, MODERATE VASOPRESSOR

VASOPRESSIN

INCREASES SVR, NO EFFECT ON HEART RATE, NO EFFECT ON CARDIAC OUTPUT, STRONG VASOPRESSOR

 

SVR=SYSTEMIC VASCULAR RESISTANCE, MAP=MEAN ARTERIAL PRESSURE

 

Topics: CVT Surgery, Medications