title: Measurement of primary haemostasis using a pressure clamp technique.
abstract: With the PFA-100 a sensitive and specific screening test for primary haemostasis has recently become available. An important part of the device is a capillary, providing a defined haemodynamic resistance for the perfusion of the aperture. A modified method to measure platelet function (VCP2) is presented in which the capillary essentially is replaced with an 'electronic capillary' by clamping the pressure/flow relationship.
  
  
  CONCLUSIONS
  Closure time (CT) and blood volume (BV) as determined by PFA-100 and VCP2 correlated well within (r = 0.922 - 0.952) and between the two methods (r = 0.86). The test variability (CV) of CT could be significantly reduced in the VCP2 method (collagen/epi 3.9 vs. 5.9%, p<0.05; collagen/ADP 3.3 vs. 6.9%, p<0.001), thus considerably increasing test reliability and reducing test variance. In preliminary clinical studies the VCP2 system showed comparable sensitivity for vWD and slightly less sensitivity regarding ASA ingestion. The test spectrum of VCP2 could be extended to more thrombocytopenic samples (< or =20 000/microl) even in combination with low haematocrit levels (20%), thus perhaps permitting the determination of the bleeding risk in bone marrow hypoplasia. Additionally, the sensitivity and applicability can easily be adapted to the desired need only by software modifications.
authors.affiliation: Department of Transfusion Medicine and Haemostaseology, University Hospital, Marburg, Germany. kretschv@mailer.uni-marburg.de
authors.forename: V
authors.initials: V
authors.lastname: Kretschmer
authors.forename: S
authors.initials: S
authors.lastname: Bade
authors.forename: M
authors.initials: M
authors.lastname: Weippert-Kretschmer
authors.forename: M A
authors.initials: MA
authors.lastname: Kratzer
mesh_terms: D001241:Aspirin / Q000031:analogs & derivatives* / Q000032:analysis; D001760:Bleeding Time / Q000295:instrumentation / Q000379:methods*; D001792:Blood Platelets / Q000473:pathology* / Q000502:physiology*; D001855:Bone Marrow Diseases / Q000097:blood; D002196:Capillaries; D005260:Female; D006400:Hematocrit; D006402:Hematologic Diseases / Q000097:blood*; D006487:Hemostasis / Q000502:physiology*; D006801:Humans; D008297:Male; D015203:Reproducibility of Results; D013921:Thrombocytopenia / Q000097:blood; D014842:von Willebrand Diseases / Q000097:blood
chemical_list: D001241:Aspirin; C006387:acetylsalicylsalicylic acid