Aspects of platelet transfusions and the association between routine coagulation tests and outcome

Patients with chemotherapy-induced bone marrow aplasia often develop severe thrombocytopenia which requires platelet transfusion. However, up to 25% of the patients show a less than adequate response to the transfusion. This phenomenon is called platelet refractoriness and is associated with increased morbidity and mortality as well as longer hospital stays and increased costs.It is well documented in the critical care setting that both a low platelet count (PLC) and a decline in PLC is associated with increased mortality. However, it is unknown whether the results of routine coagulation tests on admission to ICU may predict mortality and morbidity.Study I, performed on hematological patients receiving platelet transfusions, showed that platelet increments, measured as corrected count increments (CCI), declined in a linear manner from hours 1 to 24 post-transfusion. In patients with bone marrow aplasia due to chemotherapy for either acute leukemia or stem cell transplantation, the CCI declined 2.0% 0.6% (mean 95% confidence interval) per hour. In patients who were transfused prior to an intervention, the CCI declined 2.8% 1.2% per hour. Study II, a sub-study of Study I, showed that platelet increments did not correlate with endothelial damage measured with the endothelial cell markers syndecan-1, soluble thrombomodulin and vascular endothelial growth factor. Study III, a retrospective cohort study, showed that prolonged APTT and increased PT-INR on admission to the ICU correlated with increased mortality in patients with severe sepsis or septic shock.Study IV, a retrospective study on an unselected ICU cohort, showed that prolonged APTT on admission to the ICU correlated with increased mortality and the need for vasopressors and renal replacement therapy. Increased PT-INR was, on the other hand, not associated with mortality, but was nevertheless associated with the need for vasopressors and invasive ventilation.The findings in Studies III and IV were adjusted for severity of illness by adding the simplified acute physiology score 3 (SAPS 3) to the regression models. This means that APTT and PT-INR on admission to the ICU have a prognostic value which is not accounted for in the SAPS 3 model