Probably blood clots such as bruises.
Cardiopulmonary bypass (CPB) provides a bloodless field for cardiac surgery. It incorporates an extracorporeal circuit to provide physiological support in which venous blood is drained to a reservoir, oxygenated and sent back to the body using a pump. Team effort between surgeon, perfusionist and anaesthesiologist is paramount for the successful use of CPB. However, it also has its share of complications and strategies to reduce these complications are the area of the current research. You can use a pump, Roller pump includes two rollers positioned on a rotating arm, which compress a length of tubing to produce forward flow.
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