Laboratory Hemostasis by Sterling T. Bennett Christopher M. Lehman & George M. Rodgers

Author:Sterling T. Bennett, Christopher M. Lehman & George M. Rodgers
Language: eng
Format: epub
Publisher: Springer International Publishing, Cham

7.3.4 Cardiovascular Surgery

Cardiopulmonary bypass (CPB) procedures result in a demonstrable, transient platelet function defect that has been correlated with post-operative bleeding. Proposed causes of this platelet dysfunction include the platelet effects of high-dose heparin administered before and during the procedure, activation of platelets upon exposure to the materials that make up the CPB circuit, hypothermia, and platelet effects of protamine administration post-procedure [34]. Recent ingestion of aspirin, clopidogrel or both, frequently adds to the deleterious effect of CPB on platelet function.

Measurement of these individual or combined effects on platelet function has been reported to predict blood loss associated with CPB surgery, and clinicians have applied this observation to the incorporation of platelet function testing into transfusion protocols for cardiac surgery. Many of these trials have reported a significant decrease in allogeneic transfusions and blood loss [35]. However, it is generally difficult to sort out the relative importance of the implementation of a strict transfusion protocol versus the utility of the rapid assessment of hemostasis and platelet function at the bedside in the improved outcomes. Cardiac surgery transfusion practice can be highly variable across surgeons and institutions [36, 37], and implementation of a strict protocol, with structured indications for blood component transfusion and surgical re-exploration, most likely contributes significantly to decreased transfusions. The availability of rapid assessments of hemostasis with excellent negative predictive value for ruling out coagulopathy as a cause of excessive bleeding guides the surgeon’s approach to the differential diagnosis of excessive bleeding most likely resulting in earlier intervention to control surgical bleeding [38–40]. The relative importance of platelet function testing in these transfusion algorithms has yet to be determined.

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