title: Blood loss in cemented THA is not reduced with postoperative versus preoperative start of thromboprophylaxis.
abstract: BACKGROUND
  Thrombin formation commences perioperatively in orthopaedic surgery and therefore some surgeons prefer preoperative initiation of pharmacologic thromboprophylaxis. However, because of the potential for increased surgical bleeding, the postoperative initiation of thromboprophylaxis has been advocated to reduce blood loss, need for transfusion, and bleeding complications. Trials on timing of thromboprophylaxis have been designed primarily to detect thrombotic events, and it has been difficult to interpret the magnitude of blood loss and bleeding events owing to lack of information for bleeding volume and underpowered bleeding end points.
  
  
  OBJECTIVE
  We therefore asked whether there are differences in blood loss, transfusion requirements, and other postoperative clinical complications with preoperative versus postoperative start of thromboprophylaxis with dalteparin.
  
  
  METHODS
  In a double-blind, randomized controlled trial, 80 patients undergoing primary cemented THA were allocated to dalteparin injections starting 12 hours before or 6 hours after surgery. Blood loss was measured by weighing sponges and drapes, volume in suction drains during surgery, and wound drains until removal 24 hours postoperatively. Hemoglobin and hematocrit were recorded at predefined times during and after surgery.
  
  
  RESULTS
  We found no differences in blood loss (1081 mL ± 424 mL versus 1023 mL ± 238 mL), bleeding-related events (10% versus 17%), or number of patients who had transfusions (12 versus five) with preoperative and postoperative thromboprophylaxis, respectively. Other complications were few in both groups.
  
  
  CONCLUSIONS
  Our data suggest blood loss is similar with preoperative and postoperative initiation of dalteparin thromboprophylaxis, but indicate a trend toward fewer transfusion requirements which might favor postoperative start of thromboprophylaxis.
authors.affiliation: Martina Hansens Hospital, P.O. Box 23, 1306 Baerum Postterminal, Norway. pborg1@c2i.net
authors.forename: Pål O
authors.initials: PO
authors.lastname: Borgen
authors.forename: Ola E
authors.initials: OE
authors.lastname: Dahl
authors.forename: Olav
authors.initials: O
authors.lastname: Reikerås
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects*; D015415:Biomarkers / Q000097:blood; D016063:Blood Loss, Surgical / Q000517:prevention & control*; D001803:Blood Transfusion; D001843:Bone Cements / Q000627:therapeutic use*; D016009:Chi-Square Distribution; D017985:Dalteparin / Q000008:administration & dosage*; D004311:Double-Blind Method; D004334:Drug Administration Schedule; D005260:Female; D005343:Fibrinolytic Agents / Q000008:administration & dosage*; D006400:Hematocrit; D006454:Hemoglobins / Q000378:metabolism; D006801:Humans; D007279:Injections, Subcutaneous; D008297:Male; D008875:Middle Aged; D009664:Norway; D015207:Osteoarthritis, Hip / Q000601:surgery*; D011182:Postoperative Care; D019106:Postoperative Hemorrhage / Q000097:blood / Q000209:etiology / Q000517:prevention & control*; D011300:Preoperative Care; D011446:Prospective Studies; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D015415:Biomarkers; D001843:Bone Cements; D005343:Fibrinolytic Agents; D006454:Hemoglobins; D017985:Dalteparin