title: Effects on coagulation of intravenous crystalloid or colloid in patients undergoing peripheral vascular surgery.
abstract: BACKGROUND
  This study investigated whether haemodilution-enhanced coagulation can be demonstrated under regional anaesthesia, whether this occurs before surgery, and whether the fluid used influences the effect.
  
  
  METHODS
  Patients were randomly allocated to receive either crystalloid or colloid intravenous fluid. An epidural was administered. Samples of venous blood were taken before fluid administration, after completion of the epidural and initial fluid load, during surgery before heparin, and after 24 h. Thrombelastograph analysis was performed, and full blood count, international normalised ratio, activated partial thromboplastin time, D-dimers and thrombin-antithrombin complex were measured.
  
  
  RESULTS
  In the crystalloid group, enhanced coagulation compared with baseline was demonstrated after initial fluid load (mean (SD) r-time 10.1 (4.9) min; P < 0.033; k-time 3.5 (1.7) min; P < 0.01; alpha-angle 54.9 (13.9) degrees; P < 0.01) and before heparin administration (r-time 8.8 (3.9) min; P < 0.01; alpha-angle 54.9 (12.6) degrees; P < 0.02). There was no enhancement of coagulation in the colloid group. There were no changes from baseline after 24 h.
  
  
  CONCLUSIONS
  This study confirms that the enhanced perioperative coagulation mechanism is related to dilution, rather than surgery, and is triggered by rapid crystalloid haemodilution. Consideration should be given to the use of colloid rather than crystalloid solutions for rapid fluid loading in vasculopathic patients undergoing surgery.
authors.affiliation: Department of Anaesthesia, University of Cape Town, Medical School, Observatory, Cape 7925, South Africa.
authors.forename: T G
authors.initials: TG
authors.lastname: Ruttmann
authors.forename: M F M
authors.initials: MF
authors.lastname: James
authors.forename: J
authors.initials: J
authors.lastname: Finlayson
mesh_terms: D000328:Adult; D000368:Aged; D000765:Anesthesia, Conduction; D001777:Blood Coagulation / Q000187:drug effects*; D005260:Female; D006438:Hemodilution / Q000379:methods*; D006801:Humans; D006895:Hydroxyethyl Starch Derivatives / Q000008:administration & dosage / Q000494:pharmacology; D007262:Infusions, Intravenous; D008297:Male; D008875:Middle Aged; D016491:Peripheral Vascular Diseases / Q000097:blood* / Q000601:surgery; D010952:Plasma Substitutes / Q000008:administration & dosage / Q000494:pharmacology
chemical_list: D006895:Hydroxyethyl Starch Derivatives; D010952:Plasma Substitutes