Platelet function changes in different cardiac surgery subgroups as evaluated with an innovative technology.

OBJECTIVES: : During cardiac surgery, platelets undergo substantial changes. The purpose of this study was to assess platelet function and compare these changes between different cardiac operations using an innovative technology.

METHODS: : Perioperative platelet function was evaluated by the Impact test [cone and plate(let) analyzer (CPA)]. The Impact test yields 2 parameters for platelet function: average size (AS, the mean size of the platelet aggregates) and surface coverage (SC, the percentage of the surface covered by the platelet aggregates), which correspond to platelet aggregation and adhesion. The study groups were compared for platelet function results in various surgery stages and correlation with bleeding.

RESULTS: : A significant decrease in surface coverage was detected on establishment of cardiopulmonary bypass, with an increase up to preoperative values at the end of the surgery in all groups. In contrast to operations performed on bypass, in patients operated without cardiopulmonary bypass, the postoperative AS and SC were higher than the preoperative values, 30.4 ± 8.1 μmol versus 23.3 ± 6.9 μmol, P = 0.02 in AS, and 7.6 ± 3.6% versus 5.2 ± 1.8%, P = 0.04 in SC. Preoperative AS and SC were the only parameters significantly (P = 0.01) and linearly (r = 0.6) related to postoperative bleeding.

CONCLUSIONS: : Preoperative platelet function, as evaluated by the CPA, is an independent risk factor determining postoperative bleeding. The off-pump patients presented an increased platelet function at the end of surgery, a finding that can imply a higher risk of thrombosis. The impact test appears to be a useful tool to determine perioperative platelet function and help in prediction of postoperative bleeding.