Background:
Cardiopulmonary bypass-related platelet dysfunction can increase the risk of intra- and post-operative
bleeding in children undergoing cardiac surgery. More accurate laboratory tests that identify acquired platelet abnormalities could allow for rapid identification of patients at risk of
bleeding and provide
therapies that could reduce
bleeding and
platelet transfusions. We hypothesized that thromboelastography with platelet mapping (TEG-PM) and multiple
electrode impedance aggregometry (MEIA) as functional measures of platelet function would predict who will require
platelet transfusion. Our secondary hypothesis was that platelet aggregation at both
arachidonic acid (AA) and
adenosine diphosphate (
ADP) receptors would correlate between TEG-PM and MEIA results. Methods: In this prospective study from August 2013 to December 2015, children from newborn to 5 years of age with
congenital heart disease undergoing
cardiopulmonary bypass had blood samples collected and analyzed at four time points: pre-bypass, post-bypass, post-operatively on arrival to the Cardiac Intensive Care Unit, and 24 h after arrival. Results: Of the 44 patients analyzed, the 10 patients who received peri-operative
platelet transfusion were significantly younger (p = 0.05), had higher STAT (Society of Thoracic Surgeons-European Association for Cardio-Thoracic Surgery) Mortality Categories (p < 0.002) and longer
cardiopulmonary bypass times (p = 0.02). In univariate analysis, four variables were associated with peri-operative
platelet transfusion: pre-operative age [OR 0.95 (0.93, 0.98), p = 0.03],
cardiopulmonary bypass time [1.5 (1.31, 1.68), p = 0.008], STAT Mortality Category [3.64 (3.40, 3.87), p < 0.001], and TEG-PM
ADP [0.79 (0.65, 0.93), p = 0.04]. ROC analysis demonstrated moderate predictive value of TEG-PM
ADP with AUC of 0.745 (0.59, 0.91). A TEG-PM
ADP value of less than or equal to 21 had 85% sensitivity and 70% specificity for
platelet transfusion. In the multivariate analysis, only STAT Mortality Category predicted
platelet transfusion. TEG-PM and MEIA results correlated for the AA receptor at all 4 time points, but the same tests at the
ADP receptors did not correlate. Conclusions: TEG-PM
ADP may provide more clinically relevant information regarding platelet function compared to the MEIA at the
ADP receptor in children requiring
cardiopulmonary bypass. There was limited correlation between TEG-PM and MEIA results which raises a concern about the accuracy of these tests at the
ADP receptor. Lower pre-operative TEG-PM
ADP MA may predict intra-operative
platelet transfusions; however, larger studies are needed to determine the utility of TEG-PM and MEIA in guiding
platelet transfusions in this population.