change ECMO circuit flow rate to help with hemolysis or clotting

The shear stress of blood passing through the ECMO circuit and across the oxygenator can result in hemolysis, sometimes significant enough to cause anemia and hyperbilirubinemia. Hemolysis may also occur due to clotting on the end of the drainage cannula or a hyperinflammatory state induced by the ECMO circuit or via nitric oxide dysregulation. Hemolysis can often be diagnosed by detecting elevated bilirubin levels, elevated lactate dehydrogenase levels, low haptoglobin levels, or falling hemoglobin levels. Decreasing platelet counts may also occur due to shear stress in the ECMO circuit. Hemolysis in the ECMO circuit has been associated with morbidity and mortality. Remedies for hemolysis in the circuit include decreasing pump speed (revolutions per minute; RPMs) in order to decrease ECMO circuit blood flow, changing the ECMO circuit, or increasing the degree of anticoagulation.

Oxygenators are foreign bodies and create a thrombophilic environment. Clotting is more common under lower ECMO circuit blood flows and at lower (or no) levels of anticoagulation. Increasing the ECMO circuit blood flow results in the blood spending less time touching the foreign surface of the oxygenator and reduces clotting risk. Decreasing blood flow through the ECMO circuit results in more contact time and less laminar flow, which increases the risk of clotting. Similarly, higher levels of anticoagulation also can reduce clotting risk.1234

Footnotes

  1. SEEK Questionnaires ↩

  2. Deatrick KB, Galvagno SM, Mazzeffi MA, et al. Pilot study evaluating a non-titrating, weight-based anticoagulation scheme for patients on veno-venous extracorporeal membrane oxygenation. Perfusion. 2020;35(1):13-18. PubMed ↩

  3. Patel B, Arcaro M, Chatterjee S. Bedside troubleshooting during venovenous extracorporeal membrane oxygenation (ECMO). J Thorac Dis. 2019;11(suppl 14):S1698-S1707. PubMed ↩

  4. Williams DC, Turi JL, Hornik CP, et al. Circuit oxygenator contributes to extracorporeal membrane oxygenation-induced hemolysis. ASAIO J. 2015;61(2):190-195. PubMed ↩