The Platelet Function Analyzer (PFA‐100^®): a novel in‐vitro system for evaluation of primary haemostasis in children

Abstract

Summary. The PFA-100® system provides an in-vitro method of assessing primary platelet-related haemostasis by measuring the time (the closure time, or CT) taken for a platelet plug to occlude a microscopic aperture cut into a membrane coated with collagen and either epinephrine or ADP. We used the system to establish normal ranges for CTs in healthy children, adults and neonates. Mean CTs of healthy children were independent of the needle gauge used (21G or 23G) for blood sampling; they were very similar to the mean CTs of healthy adults, but longer than mean CTs of healthy neonates. Although children with haemophilia had normal CTs, the PFA-100 system was found to be potentially useful in screening for von Willebrand disease in children.

Antithrombotic Therapy in Neonates and Children

“…34,187,188 Using the platelet function analyzer (PFA)-100 (Dade International, Inc), cord blood samples from term neonates were found to have shorter closure times than samples from older children or adults. [189][190][191] The shorter closure time correlates with the higher hematocrit levels and increased von Willebrand factor activity (measured by ristocetin cofactor assay) in cord blood. 190 The multiplate whole-blood aggregometry analyzer also demonstrates age-related differences in platelet reactivity.…”

Migration distance-based platelet function analysis in a microfluidic system

“…[10][11][12][13][14][15][16][17] Lighttransmission aggregometry has been widely used as the gold standard to identify and diagnose defects in platelet function. 12,13 However, it requires platelet-rich plasma, a time-consuming test procedure, and large sample volumes.…”

“…11,14 A shear-induced platelet function analyzer (PFA-100, Siemens, Germany) has been introduced. 10,[15][16][17] This device lets anti-coagulated whole blood flow through a narrow hole (d ¼ 150 lm) punched in membranes coated with collagen and either ADP or epinephrine. Before passing through the membrane, the blood sample is passed through a capillary (d ¼ 200 lm) at a high shear rate (c > 5000 s À1 ) to activate the platelets as well as vWFs.…”

“…Furthermore, this method is also dependent on vWF function and hematocrits, and 2-step serial tests for different agonists (collagen-ADP and collagen-epinephrine) require double the cost and test time. 10,[15][16][17] Above all, this test requires a large blood volume (i.e., 800 ll for PFA-100), which cannot be obtained from a simple finger stick without vein puncture.…”

The Relationship of von Willebrand Factor Binding to Activated Platelets from Healthy Neonates and Adults

“…Platelet activation pathways in neonates are still not well understood and conflicting data exist on their role in the initiation and propagation of thromboembolic events. Although hyporeactivity in vitro of platelets from neonates has been reported (14 -16), the significance of this remains unclear and tests for global platelet function demonstrate hyperreactivity compared with platelets from adults (17)(18)(19)(20)(21).…”