CP12 Clear Prime Replacement
Replacement of extracorporeal clear prime with patient autologous blood before commencement of cardiopulmonary bypass (CPB). The obligatory hemodilution resulting from crystalloid priming of the CPB circuit represents a major risk factor for blood transfusion in cardiac operations. Autologous priming of the bypass circuit may result in decreased hemodilution and red cell transfusion.
The CPB circuit should be assembled and primed according to protocol, with the addition of Mannitol withheld. After heparinization (adequate activated clotting time), arterial and venous cannulation, administration of a test dose, and consultation with the surgeon and anesthesiologist, the autologous replacement of clear prime is started. The anesthesia team may start some background vasoconstriction to promote maintenance of vaso tone. The arterial line distal to the arterial filter is double clamped. The venous line is partially occluded to allow very slow exchange of patient volume, while pumping clear prime to the arterial filter and out of the manifold into a properly labeled collection bag. Patient parameters should be closely monitored to prevent hypotension.. This procedure should be continued (patient parameter permitting) until blood reaches the collection bag. Once complete, the venous line should be clamped , the centrifugal pump outlet line clamped, the manifold turned off, and after careful inspection of the pump circuit (air-free, all clamps properly placed, etc.), the double clamps distal to the arterial filter may be removed in preparation for initiation of CPB. The mannitol dose should be administered at this time. Commencement of CPB will be on command of the surgeon, as per protocol.