title: Sampling conditions influence multiple electrode platelet aggregometry in cardiac surgery patients.
abstract: OBJECTIVE
  To investigate the importance of blood sampling conditions for multiple electrode platelet aggregometry (MEA) in cardiac surgery patients.
  
  
  METHODS
  Eighty-one patients undergoing first time CABG surgery were included in three prospective, observational studies. MEA was used to analyze platelet aggregability after addition of adenosine-diphosphate (ADP) or thrombin activating peptide 6 (TRAP). In substudy 1, hirudin and citrate tubes were compared. In substudy 2, samples from peripheral vein, central venous catheter, and radial artery were compared and in substudy 3, the effect of surgery was investigated by analyzing pre- and postoperative samples.
  
  
  RESULTS
  Platelet aggregability values were 30% higher in hirudin tubes than in citrate tubes. There was a significant correlation between hirudin and citrate tubes in TRAP-induced aggregability (r = 0.84, p < 0.001) but not in ADP-induced aggregability (r = 0.25, p = 0.13). The blood sampling site did not influence platelet aggregability. Surgery reduced ADP-induced aggregability by 31% (p < 0.001) and TRAP-induced aggregability by 30% (p < 0.001) with large intraindividual variations.
  
  
  CONCLUSIONS
  MEA results in cardiac surgery patients should not be compared between samples collected in test tubes with different anticoagulants. The choice of blood sampling site does not affect the results. The operation in itself reduces markedly mean platelet aggregability.
authors.affiliation: Department of Cardiothoracic Surgery, Sahlgrenska University Hospital, Gothenburg, Sweden. martin.karlsson@vgregion.se
authors.forename: Martin
authors.initials: M
authors.lastname: Karlsson
authors.forename: Christine
authors.initials: C
authors.lastname: Roman-Emanuel
authors.forename: Linda
authors.initials: L
authors.lastname: Thimour-Bergström
authors.forename: Caroline Shams
authors.initials: CS
authors.lastname: Hakimi
authors.forename: Anders
authors.initials: A
authors.lastname: Jeppsson
mesh_terms: D000244:Adenosine Diphosphate / Q000008:administration & dosage; D000368:Aged; D000925:Anticoagulants / Q000008:administration & dosage* / Q000493:pharmacokinetics; D001800:Blood Specimen Collection / Q000379:methods; D019343:Citric Acid / Q000008:administration & dosage; D001026:Coronary Artery Bypass / Q000009:adverse effects; D004566:Electrodes; D005260:Female; D005343:Fibrinolytic Agents / Q000008:administration & dosage; D006490:Hemostatics / Q000008:administration & dosage* / Q000493:pharmacokinetics; D006493:Heparin / Q000008:administration & dosage; D006494:Heparin Antagonists / Q000008:administration & dosage; D006629:Hirudins / Q000008:administration & dosage; D006801:Humans; D008297:Male; D008875:Middle Aged; D010974:Platelet Aggregation / Q000187:drug effects; D010979:Platelet Function Tests; D011182:Postoperative Care; D019106:Postoperative Hemorrhage / Q000097:blood* / Q000175:diagnosis; D011237:Predictive Value of Tests; D011300:Preoperative Care; D011446:Prospective Studies; D011479:Protamines / Q000008:administration & dosage; D012680:Sensitivity and Specificity; D013917:Thrombin / Q000008:administration & dosage; D013997:Time Factors
chemical_list: D000925:Anticoagulants; D005343:Fibrinolytic Agents; D006490:Hemostatics; D006494:Heparin Antagonists; D006629:Hirudins; D011479:Protamines; D019343:Citric Acid; D000244:Adenosine Diphosphate; D006493:Heparin; D013917:Thrombin