crucial component of ECMO circuits are the flow sensors. At minimum, they provide measurement of blood flow rate and bubble detection. Newer sensors can also estimate hematocrit and oxygen saturation. The flow sensor is incorporated into the downstream side of the centrifugal pump. An additional clip-on sensor is sometimes included downstream of the oxygenator. In more advanced compact systems such as the Maquet CARDIOHELP, the sensors are built into the pump/oxygenator disposable component.
Blood Flow Sensor
With positive displacement pumps, the blood flow flux through the pump is determined solely by the pump speed. However, with centrifugal flow pumps that rotate at set speeds, the flow rate through the pump also depends on the upstream and downstream pressures. Therefore, an external sensor is required to provide the blood flow rate information.