Updated July 2026 · 11 min read

Impella: An ICU Nurse's Guide to the Heart Pump

Part of the ICU Devices Hub — browse every related guide in one place.

The Impella is a tiny axial-flow pump that sits across the aortic valve and actively pulls blood out of the left ventricle and pushes it into the aorta. Unlike the balloon pump, it doesn't assist the heart's own beat — it does the pumping. That makes it powerful in cardiogenic shock and high-risk PCI, and it makes position and flow the two things a nurse guards constantly.

How it unloads the heart

By continuously moving blood from the LV to the aorta, the Impella lowers LV volume and pressure. That does two good things at once: it reduces myocardial oxygen demand (a less-distended ventricle works less) and it maintains forward cardiac output and coronary/end-organ perfusion. It's used in cardiogenic shock, to protect the heart during high-risk percutaneous coronary intervention, and sometimes as a bridge to recovery or to a durable device.

P-levels and the flow you're delivering

The console runs at a set performance level (P-level) — higher P means faster rotor speed and more flow. Each device model has its own maximum flow. The team titrates the P-level to balance the support the patient needs against position stability and hemolysis. As a nurse you'll document the P-level, the flow (L/min), and the alarms, and you'll never change the P-level outside of orders/protocol.

The three waveforms/values that tell you where the pump is

Suction alarms — the most common problem

A suction event happens when the inlet doesn't have enough blood to pull — the ventricle is under-filled or the inlet is pinned against the LV wall or septum. The console alarms and flow drops. Think through the causes:

Persistent suction isn't just a nuisance — it shreds red cells and worsens hemolysis, and it means the patient isn't getting the support the number claims.

The purge system

A continuous purge fluid (typically a dextrose solution, often heparinized per protocol) runs through the motor to keep blood from entering and clotting the rotor. The console manages purge pressure automatically, but you monitor it: a rising purge pressure can signal thrombus forming in the system, and a falling pressure can signal a leak. Never let the purge run dry — a stopped purge risks pump thrombosis. Anticoagulation (systemic, plus the purge) is standard, so bleeding vigilance runs alongside.

Hemolysis and the assessment that catches it

Emergencies you cannot miss

Weaning and removal

As the heart recovers — improving output, falling pressor and inotrope needs, better echo function — the team weans the P-level in steps while watching that hemodynamics hold. Once support is no longer needed, the device is removed and the access site managed (manual pressure or a closure device), with careful post-removal limb checks.

Bottom line

The Impella does the pumping the sick ventricle can't, and it lives or dies on two things you watch minute to minute: position (placement signal + motor current) and filling (suction alarms). Keep the purge running, catch hemolysis by the urine and the labs, guard the access limb, and treat any loss of the aortic waveform or the motor current as the position emergency it is.

This article is general educational information for licensed clinicians and students, not medical advice or a substitute for your institution's protocols or a provider's orders. Always follow facility policy.