Hemolysis, Impella Education
Troubleshooting Suspected Hemolysis in Patients Supported with Impella® Heart Pump
In this educational video, Jessica Page, an advanced Impella trainer with Abiomed, defines hemolysis, reviews the clinical signs and symptoms for diagnosing hemolysis, and provides tips to reduce the risk of hemolysis with Impella heart pumps.
Definition. Hemolysis is the destruction of red blood cells and subsequent release of hemoglobin in the bloodstream. Hemolysis can be caused by certain medical conditions and medications as well as by mechanical damage to red blood cells from sources including artificial heart valves, hemodialysis, and mechanical circulatory support devices. If left untreated, hemolysis can lead to acute kidney and liver failure.
Impella pumps are designed to be blood compatible with a low risk of clinically significant hemolysis. It is, however, important to recognize clinical signs and symptoms of hemolysis and troubleshoot if needed.
Clinical signs and symptoms. Clinical signs and symptoms include blood in the urine, increased levels of lactate dehydrogenase (LDH), also known as lactic acid dehydrogenase, increased indirect bilirubin, decreased haptoglobin, and increased plasma free hemoglobin (pfHgb). Jess briefly discusses each of these, noting that blood in the urine is the least specific indication of hemolysis and plasma free hemoglobin is the most specific clinical indicator of hemolysis. PfHgb is a direct measurement of hemoglobin liberated from red blood cells in the plasma. Clinically significant hemolysis is defined as two pfHgb test results greater than 40 mg/dL in a 24-hour period.
Jess explains that the shear forces that Impella places on the red blood cell are well below the shear forces needed to damage red blood cells. She shows clinical data demonstrating that Impella heart pumps pose a lower risk of hemolysis than the standard bypass pump used in open-heart surgery.
Troubleshooting tips. If hemolysis is suspected, Jess offers the following troubleshooting tips:
- Address and correct any active position or suction alarms to help prevent hemolysis.
- If Impella malposition is suspected, use echo to look for inlet or outlet obstructions.
- If the urine is red, rule out blood in the urine with a simple urinalysis looking for whole red blood cells.
- Check whether there has been a drop in hemoglobin or if lab samples are hemolyzed.
- Check plasma free hemoglobin or spun plasma color for evidence of suspected hemolysis.
- Consider giving volume if suspected hemolysis is accompanied by a CVP or wedge pressure <10 mmHg.
In summary, the risk of clinically significant hemolysis with Impella is low when Impella is properly positioned and when suction alarms are addressed in a timely manner.