Cardiopulmonary bypass
Cardiopulmonary bypass (CPB) or heart-lung machine also called the pump or CPB pump is a machine that temporarily takes over the function of the heart and lungs during open-heart surgery by maintaining the circulation of blood and oxygen throughout the body.[1] As such it is an extracorporeal device.
CPB is operated by a perfusionist. The machine mechanically circulates and oxygenates blood throughout the patient's body while bypassing the heart and lungs allowing the surgeon to work in a bloodless surgical field.
Contraindications and special considerations[edit]
There are no absolute contraindications to cardiopulmonary bypass.[6] However, there are several factors that need to be considered by the care team when planning an operation.
Heparin-induced thrombocytopenia and heparin-induced thrombocytopenia and thrombosis are potentially life-threatening conditions associated with the administration of heparin. In both of these conditions, antibodies against heparin are formed which causes platelet activation and the formation of blood clots. Because heparin is typically used in CPB, patients who are known to have the antibodies responsible for heparin-induced thrombocytopenia and heparin-induced thrombocytopenia and thrombosis require alternative forms of anticoagulation. Bivalirudin is the most studied heparin-alternative in people with heparin-induced thrombocytopenia and heparin-induced thrombocytopenia and thrombosis requiring CPB.[7]
A small percentage of patients, such as those with an antithrombin III deficiency, may exhibit resistance to heparin. In these patients, patients may need additional heparin, fresh frozen plasma, or other blood products such as recombinant anti-thrombin III to achieve adequate anticoagulation.[8]
A persistent left superior vena cava is thoracic system variation in which the left-sided vena cava fails to involute during normal development. It is the most common variation of the thoracic venous system, occurring in approximately 0.3% of the population.[9] The abnormality is often detected on pre-operative imaging studies, but may also be discovered intra-operatively. A persistent left superior vena cava may make it difficult to achieve proper venous drainage or deliver of retrograde cardioplegia. Management of a persistent left superior vena cava during CPB depends on factors such as the size and drainage site of the vena cava variation.[10]
Technique[edit]
Pre-operative planning[edit]
CPB requires significant forethought before surgery. In particular, the cannulation, cooling, and cardio-protective strategies must be coordinated between the surgeon, anesthesiologist, perfusionist, and nursing staff.[17]