Anticoagulation, Impella Education, Patient Management
Calculating Total Heparin Rate
When supporting a patient with an Impella® heart pump, it is important to account for the heparin in the purge fluid when calculating the total heparin rate to avoid supertherapeutic dosing. In this video, Jo Kajewski, an advanced Impella® trainer, discusses how to account for the Impella delivered heparin.
Jo explains that the primary purpose of the purge fluid is to prevent blood from entering the Impella motor. The purge fluid creates a pressure barrier, which must always be greater than 300 mmHg.
The Automated Impella Controller™(AIC) controls the purge fluid rate, attempting to maintain the rate between 2 and 30 mL/hr. Heparin is added to the purge fluid for additional motor protection. D5W with heparin 25 U/mL or 50 U/mL is acceptable.
While a patient is supported with Impella, clinicians should strive to maintain the activated clotting time (ACT) between 160 and 180 seconds. To meet this requirement, patients may require an IV heparin drip in addition to the heparin in the purge fluid. Therefore, when calculating the total heparin rate for a patient, clinicians must be sure to include both the heparin in the systemic drip and the heparin the purge fluid.
The Infusion History screen on the AIC provides information to help you account for heparin administered to the patient in the purge fluid. To see this information, press the Display soft button and then select Infusion. The Infusion History screen provides an hourly breakdown of the fluid and heparin given to the patient.
Jo shows a systemic IV heparin rate calculator to assist in calculating the systemic IV heparin rate. First, calculate the Impella delivered heparin rate by multiplying the heparin concentration in the purge fluid (U/mL) by the infusion rate (mL/hr) shown on the AIC. Then, subtract the Impella delivered heparin rate from the total patient heparin rate recommended by the hospital protocol or pharmacy. This will provide you with the systemic IV heparin rate.