title: Deliberate hypotension in orthopedic surgery reduces blood loss and transfusion requirements: a meta-analysis of randomized controlled trials.
abstract: OBJECTIVE
  To determine if deliberate hypotension decreases blood loss and transfusion requirements in patients undergoing orthopedic surgery, a systematic review of all randomized trials addressing this issue was undertaken.
  
  
  METHODS
  Electronic databases, citations lists and review articles were searched for potential articles. Relevant articles met the following inclusion criteria: English language, humans undergoing orthopedic surgery, deliberate hypotension used by any method, intraoperative blood loss measured as an outcome, and the trial methodology being randomized and controlled. Four outcomes were analyzed, including estimated blood loss, blood transfused, surgery duration, and quality of the surgical field. For all analyses, the random-effects model was used.
  
  
  RESULTS
  Seventeen articles met the inclusion criteria. The surgeries studied included total hip arthroplasty (seven), orthognathic surgery (eight), total knee arthroplasty (one) and spinal fusion (one). A total of 636 patients were randomized across all studies. For blood loss, the overall weighted mean difference favoured treatment, with a savings of about 287 mL of blood [95% confidence interval (CI): -447, -127]. The mean differences also showed a statistically significant benefit for deliberate hypotension in reducing transfusion requirements (-667 mL of blood transfused; 95% CI: -963, -370). Deliberate hypotension was not shown to reduce the duration of surgery (-1.9 min of surgery; 95% CI: -7.2, 3.5) or improve surgical conditions (surgical field quality rating -0.5; 95% CI: -1.1, 0.2).
  
  
  CONCLUSIONS
  This review provides some support for the use of deliberate hypotension in reducing blood loss and transfusion requirements in orthopedic surgery, but these results are tempered by the small sample sizes and poor methodological quality of published studies.
authors.affiliation: Department of Anesthesia, Hamilton Health Sciences, McMaster University, Hamilton, Ontario, Canada. james_paul@sympatico.ca
authors.forename: James Edward
authors.initials: JE
authors.lastname: Paul
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Ling
authors.forename: Carlos
authors.initials: C
authors.lastname: Lalonde
authors.forename: Lehana
authors.initials: L
authors.lastname: Thabane
mesh_terms: D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects; D016063:Blood Loss, Surgical / Q000517:prevention & control*; D001803:Blood Transfusion; D006801:Humans; D007023:Hypotension, Controlled / Q000379:methods*; D019647:Oral Surgical Procedures / Q000009:adverse effects; D019637:Orthopedic Procedures / Q000009:adverse effects* / Q000379:methods; D016032:Randomized Controlled Trials as Topic; D013123:Spinal Fusion / Q000009:adverse effects