What issues can arise if the pressure drop is too high in an ECMO cannula?

A high pressure drop in an ECMO cannula can lead to hemolysis, which is the destruction of red blood cells. This occurs because a significant pressure drop indicates that the blood is encountering excessive turbulence or shear stress as it flows through the cannula. The mechanical forces exerted on the red blood cells can cause them to rupture, releasing hemoglobin into the plasma. Hemolysis can subsequently lead to several complications, including anemia, jaundice, and elevated levels of potassium, among other metabolic disturbances.

In contrast, while hypotension, cannula obstruction, and drops in oxygen saturation can be related to other issues within the ECMO circuit or patient condition, they are not direct consequences of a high pressure drop in the cannula itself. Hypotension could result from inadequate blood flow rather than the pressure drop. Cannula obstruction typically indicates physical blockage, and a drop in oxygen saturation is more likely related to other perfusion problems rather than directly from the effects of pressure dynamics in the cannula. Thus, hemolysis stands out as a critical and direct consequence of excessive pressure drop in ECMO systems.