From the Guidelines
Impella signals are managed in a patient through continuous monitoring of the device's console display and waveforms, with a focus on optimizing device function and patient safety during mechanical circulatory support. The healthcare team should regularly assess the placement signal, motor current, and purge system parameters to ensure proper device functioning. According to the American Heart Association's scientific statement on invasive management of acute myocardial infarction complicated by cardiogenic shock 1, the placement signal should show appropriate aortic and ventricular waveforms to confirm correct positioning.
Key parameters to monitor include:
- Motor current, which typically ranges between 300-700 mA during normal operation
- Purge system pressure, which should be maintained between 300-1100 mmHg with flow rates of 2-30 mL/hr
- Suction events, indicated by flat ventricular waveforms, which require immediate attention
- Hemolysis markers and device alarms, which should be regularly checked to prevent complications
If signal abnormalities occur, immediate actions include repositioning the device under imaging guidance, adjusting the performance level (P-levels), or troubleshooting the purge system 1. Anticoagulation with heparin, with a target activated clotting time (ACT) of 160-180 seconds or partial thromboplastin time (PTT) of 45-60 seconds, is typically required to prevent thrombus formation 1. Regular assessment of the patient's hemodynamics, including cardiac output, blood pressure, and end-organ perfusion, should guide adjustments to the Impella support level to ensure optimal patient outcomes.
In terms of specific management strategies, the Detroit Cardiogenic Shock Initiative encouraged an aggressive protocol of early mechanical circulatory support (MCS) in the management of patients with acute myocardial infarction complicated by cardiogenic shock, with 85% of patients surviving to device explantation 1. However, the IABP-Shock II trial found no difference in 30-day all-cause mortality between patients treated with an intra-aortic balloon pump (IABP) and those receiving conservative care 1. Therefore, the choice of MCS device and management strategy should be individualized based on patient-specific factors and clinical judgment.
From the Research
Impella Signal Management
Impella signals are managed in patients through various methods, including:
- Monitoring of purge flow rates and pressures to detect potential thrombosis or hemolysis 2
- Use of anticoagulation protocols, such as unfractionated heparin (UFH) purge solutions and intravenous UFH continuous infusion, to prevent thrombosis 3
- Targeting specific anti-Xa goals, such as 0.3 to 0.5 units/mL, to minimize bleeding and thrombotic complications 3
- Adjusting whole activated clotting time (ACT) levels, with a recommended range of 160 to 180 seconds, to prevent pump thrombosis and bleeding 4
Alternative Purge Solutions
In patients with heparin-induced thrombocytopenia (HIT) or coagulopathy, alternative purge solutions may be used, such as:
- Sodium bicarbonate purge solution, which has been shown to be effective in preventing device dysfunction and thrombosis in patients with HIT 5
- Bicarbonate-based purge solution, which has been used successfully in a coagulopathic patient with minimal systemic effects 6
Signal Detection and Response
Impella signals, such as decreased purge flow rates and increased purge pressures, can indicate potential thrombosis or hemolysis, and prompt response is necessary to prevent complications, including: