Qualitative and quantitative changes in platelets after coronary-artery bypass surgery may help identify thrombotic complications and infections.

We studied the effect of coronary-artery bypass surgery on blood cells and platelets. Hematological parameters of eighty-three patients were measured by an automated cell counting and sizing analyzer. Sampling time was from 24 h prior to 10 days after surgery. During this time leukocytes and platelets showed characteristic changes in numbers and size, whereas red blood cells revealed no typical modifications. Even though it seems clear that changes of hematological parameters occur after bypass surgery, it is important to be aware of the actual extent of such changes. Therefore the data of 50 patients who had had no post-operative clinical complications were combined to generate diagrams of those parameters that had changed in a characteristic fashion. The diagrams showing average changes, and 99% confidence intervals in mean platelet volume and platelet count were able to identify seven (out of 7) cases with complications up to 48 h before clinical signs were apparent. Complications ranged from mild (3 cases with infections) to severe (4 cases with thrombosis, embolic thrombosis and/or reinfarction). Diagrams showing changes in leukocyte parameters were able to identify only two cases with infections. Even though the number of cases is yet small, the results suggest that surveillance of platelet parameters may be useful in postoperative care. Furthermore, this study was able to confirm the recent findings of Trowbridge and Martin that an abnormal increase in platelet volume distribution width and low platelet counts found in patients with coronary heart disease may serve as good indicators for the prethrombotic state and the risk of myocardial infarction.