title: A retrospective audit to examine the effectiveness of preoperative warming on hypothermia in spine deformity surgery patients.
abstract: BACKGROUND
  Hypothermia (core body temperature <36°C) during surgery has been associated with surgical site infection, a major risk in all spine deformity surgeries. Forced air warming is an important method of intraoperative temperature maintenance in children. In mid-2010, we empirically introduced preoperative warming as a strategy to reduce intraoperative hypothermia.
  
  
  OBJECTIVE
  We report the prevalence and extent of hypothermia during spine deformity surgeries at our institution and evaluate the effect of the introduction of preoperative warming.
  
  
  METHODS
  We performed a retrospective audit of temperature data in children who underwent spine deformity surgeries during two-seven-month periods: November 2011 to June 2012 and 2 years prior to this period (before preoperative warming implementation). Specifically, the following data were obtained: (i) case duration; (ii) first measured temperature; (iii) last measured temperature; (iv) percentage of case spent hypothermic; (v) number of hypothermic episodes per case, and (vi) delay between case start and time of first temperature measured. Data were compared visually and using the Mann-Whitney U-test. Confidence intervals (CI) were obtained using the Hodges-Lehmann estimator.
  
  
  RESULTS
  Preoperative warming reduced the percentage of case duration spent hypothermic by a median of 111.1 min (P < 0.001, 95% CI 77.1-139.9 min). Additionally, it increased the first measured temperature by a median of 0.5°C (P < 0.001, 95% CI 0.3-0.7°C). The last temperature at the end of the case remained unchanged (P = 0.57, 95% CI -0.2-0.1°C).
  
  
  CONCLUSIONS
  Preoperative warming of children undergoing spine deformity surgery significantly reduces the percentage of case spent hypothermic, thereby potentially reducing risk of perioperative complications.
authors.affiliation: Department of Electrical and Computer Engineering, The University of British Columbia, Vancouver, BC, Canada.
authors.forename: Matthias
authors.initials: M
authors.lastname: Görges
authors.forename: J Mark
authors.initials: JM
authors.lastname: Ansermino
authors.forename: Simon D
authors.initials: SD
authors.lastname: Whyte
mesh_terms: D001831:Body Temperature; D002648:Child; D015331:Cohort Studies; D003627:Data Interpretation, Statistical; D005189:False Positive Reactions; D006801:Humans; D007035:Hypothermia / Q000453:epidemiology / Q000517:prevention & control*; D007431:Intraoperative Complications / Q000453:epidemiology / Q000517:prevention & control*; D008485:Medical Audit; D010100:Oxygen / Q000097:blood; D011237:Predictive Value of Tests; D011300:Preoperative Care; D015995:Prevalence; D012372:ROC Curve; D012189:Retrospective Studies; D017694:Rewarming / Q000379:methods*; D012600:Scoliosis / Q000601:surgery*; D013131:Spine / Q000002:abnormalities*
chemical_list: D010100:Oxygen
keywords: anesthesia; general/adverse effects; healthcare quality assurance; hot temperature/therapeutic use; hypothermia/prevention and control; intraoperative/methods; monitoring; scoliosis/surgery