title: Mild hypothermia does not increase blood loss during total hip arthroplasty.
abstract: BACKGROUND
  The effects of mild hypothermia on blood loss are little known.
  
  
  METHODS
  Patients, undergoing primary prosthetic hip surgery under spinal anaesthesia, were randomised to the operative procedure, with (n=25) or without (n=25) forced air warming. Core temperature was repeatedly measured from the tympanic membrane. The blood loss was calculated by three different methods; the intraoperative loss was estimated visually. The loss during and after the operation was obtained by determination of lost haemoglobin (the Hb-method). The blood loss during hospital stay was also calculated from the haemoglobin balance.
  
  
  RESULTS
  Among controls, core temperature decreased by 1.3+/-0.6 degrees C (mean+/-SD) and in the warmed patients 0.5+/-0.4 degrees C (P<0.0001). Preoperative variables and the number of allogeneic units transfused did not differ between the groups. In controls, the blood loss during operation was, with the visual method, 698+/-314 ml, compared with 665+/-292 ml in warmed patients. With the Hb-method, the loss was 662+/-319 and 657+/-348 ml, respectively. With this method, the external loss during the entire hospital stay was, in controls, 1066+/-441 ml and in the warmed group, 1047+/-413 ml. The balance method yielded 1674+/-646 ml and 1507+/-652 ml, respectively. Indices of blood loss did not differ significantly between groups and there was no covariation between those variables and the decrease in core temperature.
  
  
  CONCLUSIONS
  Forced air warming did not decrease the blood loss. Methods for determination of blood loss yielded widely differing results.
authors.affiliation: Department of Orthopaedics, University Hospital, Linköping, Sweden.
authors.forename: T
authors.initials: T
authors.lastname: Johansson
authors.forename: B
authors.initials: B
authors.lastname: Lisander
authors.forename: I
authors.initials: I
authors.lastname: Ivarsson
mesh_terms: D000368:Aged; D000775:Anesthesia, Spinal; D019644:Arthroplasty, Replacement, Hip; D016063:Blood Loss, Surgical; D001803:Blood Transfusion; D001831:Body Temperature; D005260:Female; D006454:Hemoglobins / Q000032:analysis; D006801:Humans; D007035:Hypothermia / Q000503:physiopathology*; D007431:Intraoperative Complications / Q000503:physiopathology; D008297:Male
chemical_list: D006454:Hemoglobins