Effects of platelet transfusion on post cardiopulmonary bypass bleeding

Evaluation of platelet count and platelet function analyzer - 100 testing for prediction of platelet transfusion following coronary bypass surgery

Platelet transfusions are commonly administered to treat bleeding in cardiac surgery. The aim of this study was to compare platelet (PLT) count and values of collagen adenosine diphosphate closure time (cADP-CT) measured by Platelet Function Analyzer (PFA) for prediction of PLT transfusion therapy following coronary bypass surgery. For this prospective observational study, 66 patients scheduled for coronary artery bypass grafting (CABG) who received early PLT transfusions (within 60 min after the operation) were enrolled. To assess changes in platelets, count and function, two time points were selected: 15 min before and 30 - 60 min after the end of PLT transfusion. The patients were divided into transfused and non-transfused with further PLT in the 48 h postoperatively. We used the receiver operating characteristics (ROC) curve to investigate whether the PLT count and cADP-CT values were predictors of PLT transfusion. The positive predictive values (PPV) of PLT count and cADP-CT after PLT transfusion for further PLT transfusion were 33% and 86% respectively, with a PLT count threshold of ≤200 × 10⁹/L and cADP-CT threshold of ≥118 s. The comparison among the ROC curves showed a statistical difference (p = .0002). In multiple regression analysis, cADP-CT was the strongest predictor for the number of PLT transfusion doses in the 48 h postoperatively. In CABG patients, the results of cADP-CT after PLT transfusion have a better predictive capacity for further PLT transfusions than the PLT count.

Does a Platelet Transfusion Independently Affect Bleeding and Adverse Outcomes in Cardiac Surgery?

Background

Conflicting results have been reported concerning the effect of platelet transfusion on several outcomes. The aim of this study was to assess the independent effect of a single early intraoperative platelet transfusion on bleeding and adverse outcomes in cardiac surgery patients.

Methods

For this observational study, 23,860 cardiac surgery patients were analyzed. Patients who received one early (shortly after cardiopulmonary bypass while still in the operating room) platelet transfusion, and no other transfusions, were defined as the intervention group. By matching the intervention group 1:3 to patients who received no early transfusion with most comparable propensity scores, the reference group was identified.

Results

The intervention group comprised 169 patients and the reference group 507. No difference between the groups was observed concerning reinterventions, thromboembolic complications, infections, organ failure, and mortality. However, patients in the intervention group experienced less blood loss and required vasoactive medication 139 of 169 (82%) versus 370 of 507 (74%; odds ratio, 1.65; 95% CI, 1.05 to 2.58), prolonged mechanical ventilation 92 of 169 (54%) versus 226 of 507 (45%; odds ratio, 1.47; 94% CI, 1.03 to 2.11), prolonged intensive care 95 of 169 (56%) versus 240 of 507 (46%; odds ratio, 1.49; 95% CI, 1.04 to 2.12), erythrocytes 75 of 169 (44%) versus 145 of 507 (34%; odds ratio, 1.55; 95% CI, 1.08 to 2.23), plasma 29 of 169 (17%) versus 23 of 507 (7.3%; odds ratio, 2.63; 95% CI, 1.50–4.63), and platelets 72 of 169 (43%) versus 25 of 507 (4.3%; odds ratio, 16.4; 95% CI, 9.3–28.9) more often compared to the reference group.

Conclusions

In this retrospective analysis, cardiac surgery patients receiving platelet transfusion in the operating room experienced less blood loss and more often required vasoactive medication, prolonged ventilation, prolonged intensive care, and blood products postoperatively. However, early platelet transfusion was not associated with reinterventions, thromboembolic complications, infections, organ failure, or mortality.

Primary and secondary hemostatic functionalities of rehydrated, lyophilized platelets

BACKGROUND

The rehydrated, lyophilized (RL) platelet (PLT) is being developed as a hemostatic infusion agent for the control of active bleeding. The key to the method for preparing RL PLTs is a mild aldehyde stabilization that allows for freezing and lyophilizing without cellular rupture. RL PLTs have been shown to be effective at rapidly controlling bleeding in animal models of cardiopulmonary bypass induced PLT dysfunction and washout thrombocytopenia, yet the rehydrated cells have proved to be safe with respect to induction of pathologic intravascular coagulation.

STUDY DESIGN AND METHODS

In vitro and in vivo studies were performed to better understand the differential effect of the RL PLT manufacturing method on primary and secondary hemostatic processes. The functionality of the von Willebrand factor (VWF) receptor (glycoprotein Ib) complex, the PAR receptors, integrin-mediated aggregation (inside-out signaling), and surface membrane prothrombin to thrombin conversion systems were investigated.

RESULTS

RL PLTs were found to retain native VWF-mediated adhesion and surface thrombin generation functions. In contrast, the coupling of thrombin receptors to integrin inside-out signaling was largely inhibited.

CONCLUSION

These results suggest that RL PLTs may stop bleeding by forming primary hemostatic plugs and providing a localized source of thrombin for secondary hemostatic processes, yet do not build up occlusive pathologic clots possibly because integrin functions for forming PLT-PLT aggregates are partially inhibited.