In this episode, I’ll discuss an alternative to a dextrose-based purge solution for patients with an Impella ventricular assist device that also need a PET scan.
Positron emission tomography (PET) scanning uses a tracer such as fluoro-deoxyglucose which gets picked up by cells in place of regular glucose for metabolism. Excess administration of glucose may compete with the tracer for uptake into cells and therefore IV dextrose containing solutions are stopped several hours before tracer administration to prevent interference with the PET scan.
Impella ventricular assist devices use a dextrose-based purge solution to keep blood from entering the device motor. This purge solution enters systemic circulation and therefore would create a potential for PET scan interference in the rare scenario that a patient on an Impella device also required a PET scan.
While saline is usually a suitable substitute for IV solutions in place of dextrose, saline solutions are contraindicated as purge solutions for the Impella device due to the chance of corrosion of the motor.
A group of authors recently published in AJHP a two patient case series looking at the use of a sterile water and sodium bicarbonate based purge solution for patients with an Impella device that required a PET scan. The patients were a 52 year old male and a 65 year old male both of which required the Impella for cardiogenic shock and the PET scan to rule out sources of infection and/or malignancy. Both patients also received systemic anticoagulation with a heparin infusion.
In both cases, 8 hours before the PET scan the dextrose-based purge solution was replaced with sodium bicarbonate 150 mEq in 1 liter of sterile water. In both patients the PET scan was completed without incident and no clinically significant changes in purge pressure, purge flow rate, or the performance level of the Impella were observed.
The authors conclude this sterile water and sodium bicarbonate based purge solution coupled with short-term restriction of dextrose is a practical option for PET imaging in patients with an Impella ventricular assist device.
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