Best Practices for Patients Supported with Impella® (Part 4): Addressing Impella Alarms
Suction, low pulsatility, and placement signal blocked are 3 of the more common reasons for Impella® heart pump alarms. In this video, Behnam N. Tehrani, MD, FSCAI, discusses why these situations cause alarms and how to handle the alarms.
Several factors may cause a Suction alarm, including inadequate left ventricular filling, incorrect Impella position against the papillary muscle or the mitral valve in the left ventricle, or right ventricular failure. Suction can cause lower than expected Impella flow and increase the risk of hemolysis. If a suction alarm occurs, reduce the Impella P-level by 1 or 2 levels, or further, if suction continues. Assess the patient’s volume status, look at hemodynamics and confirm RV function, and evaluate catheter position using the placement signal, motor current, and imaging. Reposition Impella if necessary. When the suction alarm is resolved, resume pre-alarm flow rate.
Low native heart pulsatility
Patients with profound left ventricular dysfunction may have low native heart pulsatility. Decreased pulsatility, which is common and represents a low flow state in the ventricle, can trigger an Impella Position Unknown alarm.
In patients with low pulsatility, consider increasing Impella flow, assess Impella position using echo, and reposition if necessary. Dr. Tehrani also emphasizes checking other factors, such as high afterload, that may affect pulsatility. Notably, he states, “Treat the patient, not the device. It’s important to know how the device works, but at the end of the day, it’s very important to treat the patient.”
Dr. Tehrani also emphasizes the importance of getting results, such as lactate levels, every hour after a myocardial infarction. “We really want to make sure that we’re not falling behind on these patients’ hemodynamics, because all you need is a set of 3 or 4 numbers, and you basically have an idea of where the patient’s going to be the rest of the day.”
Placement signal lumen blocked
The Placement Signal Lumen Blocked alarm can occur if there is a clot in the placement signal lumen or it may occur if the roller clamp to the saline pressure bag is closed or partially closed or if the pressure in the bag is less than 300 mmHg. After checking the roller clamp and pressure in the bag, flush the luer. If flushing is not successful, use the motor current waveform to ensure proper positioning across the aortic valve. If, however, the line will not aspirate, do not flush the lumen as this may dislodge emboli. Be aware that the Impella catheter will still function properly without the placement signal.