Activated platelets and impaired platelet function in intensive care patients analyzed by flow cytometry.

Intensive care patients often have disturbances in their coagulation and fibrinolysis systems, which may result in haemorrhage or disseminated intravascular coagulation (DIC). DIC is a dreaded complication that may develop rapidly and has a high mortality rate. Platelets play a central role in haemostasis and it is thus important to have assays that rapidly can monitor platelet activation and platelet function. We have used flow cytometry to measure platelet activation and function in intensive care patients. Fluorescein labelled chicken antibodies were used to detect platelet bound fibrinogen as these antibodies have advantages over mammalian antibodies in flow cytometry. We found increased levels of circulating activated platelets and microparticles in vivo and impaired platelet function after stimulation in vitro. The two patients with the highest percentage of microparticles died shortly after blood sampling.