Knowledge of the blood flow in the ECMO circuit is critical for managing the patient safely. If the circuit is driven by a positive displacement pump, the blood flow rates are determined solely by the pump. However, with centrifugal flow pumps, the flow rate is dependent not only on the pump rotational speed, but also upstream and downstream pressures. In this case, ultrasonic flow transducers provide are able accurate measurements on circuit blood flow.

With the Maquet ROTAFLOW Centrifugal Pump, the flow sensor is located on the downstream side of the pump. It clamps over the circuit tubing going to the oxygenator.