In this episode, I’ll discuss whether milrinone can be used in patients on CRRT.
Occasionally ICU patients undergoing continuous renal replacement therapy (CRRT) will also require inotropic support for conditions like heart failure with reduced ejection fraction in the setting of decreased cardiac contractility.
Dobutamine and milrinone are the two IV agents available for inotropic support in the US.
Dobutamine has no dose adjustment recommendations for patients in renal failure or receiving CRRT because it is metabolized in the tissues and liver and has a half-life of about 2 minutes.
Milrinone on the other hand is almost entirely excreted in the urine as unchanged drug and has a half-life of about 2 hours in patients with normal renal function. Milrinone labeling suggests a renal dose adjustment for patients with creatinine clearance between 10 and 50 mL/min but has no recommendations or data available for patients with ESRD or who are receiving CRRT.
A pair of articles consisting of a 6 patient case series published in 2000 and a single case report published in 2005 represents the entire published literature on using milrinone in patients on CRRT.
In the case series all 6 patients had severe congestive heart failure and received milrinone 0.25 mcg/kg/min while undergoing continuous venovenous hemofiltration.
Patients had milrinone concentrations checked and pharmacokinetics were analyzed. The half-life of milrinone in these patients was about 20 hours which is 10 times greater than would be expected in patients with normal renal function.
The authors noted that:
All patients died within 1 month after the injection of milrinone because of severe forms of arrhythmia, such as ventricular tachycardia and ventricular fibrillation.
The single case report was of a 79-year-old woman who was undergoing chronic hemodialysis. She received a continuous infusion of milrinone for about 5 days while she was also undergoing continuous venovenous hemofiltration. This patient’s only arrhythmia that developed while on milrinone was atrial fibrillation, but she did have a plasma level drawn that was about 4 times the upper limit of the normal therapeutic range.
Based on these patient cases and the known kinetics of milrinone, I advise providers that if dobutamine can be used to accomplish the same clinical goals that it is preferable to milrinone in patients undergoing CRRT.
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