Use of the PFA-100 (R) in the assessment of primary, platelet-related hemostasis in a pediatric setting

The platelet function analyzer, PFA-100(R), has been designed to provide an in vitro measure of primary hemostasis simply, quickly, quantitatively, an d accurately to aid in the routine screening of patients with potential hem orrhagic risk due to abnormal platelet plug formation. The system measures the closure time (CT), or the time taken for platelets in a sample of antic oagulated blood to form a plug that occludes a microscopic aperture cut int o a membrane coated with collagen and either epinephrine or ADP The high sh ear stresses produced in the analyzer lead to platelet plug formation that is greatly dependent on von Willebrand's factor (vWF), In this article, we detail the system itself and describe our initial studies using the PFA-100 (R) to assess primary hemostasis in pediatric populations. Normal ranges ha ve been established for healthy children and neonates, CTs for healthy chil dren are independent of the needle gauge (21G or 23G) used for blood sampli ng, They are similar to CTs for healthy adults, but neonates have significa ntly shorter CTs, likely due to increased levels of 7 vWF. Children with he mophilia have normal CTS, whereas seven out of eight patients with von Will ebrand's disease (vWD) have abnormally long CTs, CT reproducibility between duplicate samples is excellent. Our preliminary results indicate that the PFA-100(R) wilt be useful in the evaluation of primary hemostasis in childr en, as well as in adults.