title: Intraoperative changes in platelet function in relation to moderate haemorrhage.
abstract: BACKGROUND
  Haemorrhage is associated with haemostatic dysfunction. Previous studies have focused on coagulation factors, but platelet function plays an equally important role. The time course of alterations in platelet function in relation to injurious stimuli is not known.
  
  
  OBJECTIVE
  To evaluate short-term, intra-operative changes in platelet function, by whole blood impedance aggregometry in patients undergoing hip arthroplasty. The primary outcome was platelet aggregation in response to adenosine diphosphate (ADP) stimulation. We also evaluated other agonists, and the feasibility of conducting platelet aggregometry measurement in the operating theatre.
  
  
  METHODS
  Patients undergoing primary cemented hip arthroplasty had six peri-operative arterial blood samples analysed at pre-set stages of the operation, using the Multiplate Impedance Aggregometer. Four agonists were used: ADP, TRAP, Collagen and Arachidonic Acid.
  
  
  RESULTS
  There was a statistically significant change (p<0.05, ANOVA) in platelet response to ADP over the course of the operations. The trend demonstrated an initial decrease in responsiveness, followed by increased platelet responsiveness in the later stages. Other agonists (TRAP, COL, ASPItest) demonstrated a similar pattern of changes. Of 360 tests conducted, 12 (3.3%) had to be re-run due to poor intra-assay variability. Satisfactory values were obtained on the second attempt in all 12 samples.
  
  
  CONCLUSIONS
  Platelet function, as measured by impedance aggregometry, changes in response to a surgical stimulus involving blood loss. The clinical significance of these changes, and the potential of manipulating them for therapeutic purposes, remains to be elucidated.
authors.affiliation: Aberdeen Royal Infirmary, NHS Grampian. Electronic address: jonathan.hetherington@nhs.net.
authors.forename: Jonathan J
authors.initials: JJ
authors.lastname: Hetherington
authors.affiliation: School of Medicine & Dentistry, University of Aberdeen.
authors.forename: Isobel
authors.initials: I
authors.lastname: Ford
authors.affiliation: School of Medicine & Dentistry, University of Aberdeen.
authors.forename: G Patrick
authors.initials: GP
authors.lastname: Ashcroft
authors.affiliation: Aberdeen Royal Infirmary, Aberdeen & Health Services Research Unit, University of Aberdeen, Aberdeen, Scotland.
authors.forename: Jan O
authors.initials: JO
authors.lastname: Jansen
mesh_terms: D000244:Adenosine Diphosphate / Q000737:chemistry; D000368:Aged; D000925:Anticoagulants / Q000627:therapeutic use; D016718:Arachidonic Acid / Q000737:chemistry; D019644:Arthroplasty, Replacement, Hip; D001780:Blood Coagulation Tests; D001792:Blood Platelets / Q000276:immunology; D003094:Collagen / Q000737:chemistry; D005260:Female; D006470:Hemorrhage / Q000097:blood* / Q000188:drug therapy; D006801:Humans; D007432:Intraoperative Period; D008297:Male; D008875:Middle Aged; D010446:Peptide Fragments / Q000737:chemistry; D015539:Platelet Activation / Q000187:drug effects; D010974:Platelet Aggregation; D010975:Platelet Aggregation Inhibitors / Q000737:chemistry; D010979:Platelet Function Tests / Q000379:methods*; D011446:Prospective Studies
chemical_list: D000925:Anticoagulants; D010446:Peptide Fragments; D010975:Platelet Aggregation Inhibitors; C086309:thrombin receptor peptide SFLLRNP; D016718:Arachidonic Acid; D000244:Adenosine Diphosphate; D003094:Collagen
keywords: Haemorrhage; Platelet aggregation; Platelet function tests; Surgery