Cardiopulmonary bypass (CPB) is a method that temporarily takes over the function of the heart and lungs during surgery, maintaining the human blood and oxygen circulation. The CPB pump, often also named as heart-lung machine (HLM), deals with human lives. Hence, technical requirements are specifically high. A reliable operation of all utilized equipment must be guaranteed at all times. For that reason, combining flow measurement and air bubble detection constitutes a significant safety and comfort feature.