title: Hypothermia and operative mortality during on-pump coronary artery bypass grafting.
abstract: OBJECTIVE
  Controversy surrounds the effect of hypothermia on operative mortality during cardiac surgery. The present study accessed a large clinical database of coronary artery bypass graft operations to address the issue.
  
  
  METHODS
  A retrospective review of the Society of Thoracic Surgeons Adult Cardiac Surgery Database identified patients treated with isolated, nonemergency, on-pump coronary artery bypass grafting from July 2011 to December 2012. The patients were divided into 3 groups according to their lowest core temperature during the procedure: moderate hypothermia (≤ 34 °C), mild hypothermia (>34 °C but ≤ 36 °C), and normothermia (>36 °C). The primary endpoint of the study was operative mortality, defined according to the Database criteria.
  
  
  RESULTS
  During the study period, 142,541 patients were available for analysis; 94,777 (66.5%) received moderate hypothermia, 42,750 (30.3%) mild hypothermia, and 5014 (3.5%) normothermia. Operative mortality occurred in 1394 patients (1.5%) in the moderate hypothermia, 534 (1.3%) in the mild hypothermia, and 105 (2.1%) in the normothermia group. Multivariate analysis identified hypothermia (both mild [odds ratio, 0.66; 95% confidence interval, 0.54-0.81; P < .0001] and moderate [odds ratio, 0.73; 95% confidence interval, 0.60-0.89; P = .0015]) was protective against operative mortality compared with normothermia. No incremental benefit was noted between the different hypothermia grades (P = .0827).
  
  
  CONCLUSIONS
  Most patients receive hypothermia during on-pump coronary artery bypass grafting. Hypothermia is protective against operative mortality compared with normothermia in such patients. Moderate hypothermia does not provide additional survival benefit.
authors.affiliation: Division of Cardiovascular Surgery, Mayo Clinic, Rochester, Minn. Electronic address: greason.kevin@mayo.edu.
authors.forename: Kevin L
authors.initials: KL
authors.lastname: Greason
authors.affiliation: Duke Clinical Research Institute, Durham, NC.
authors.forename: Sunghee
authors.initials: S
authors.lastname: Kim
authors.affiliation: Division of Cardiovascular Surgery, Mayo Clinic, Rochester, Minn.
authors.forename: Rakesh M
authors.initials: RM
authors.lastname: Suri
authors.affiliation: Duke Clinical Research Institute, Durham, NC.
authors.forename: Amelia S
authors.initials: AS
authors.lastname: Wallace
authors.affiliation: Duke Clinical Research Institute, Durham, NC.
authors.forename: Brian R
authors.initials: BR
authors.lastname: Englum
mesh_terms: D000368:Aged; D001833:Body Temperature Regulation; D002315:Cardiopulmonary Bypass / Q000009:adverse effects / Q000401:mortality*; D001026:Coronary Artery Bypass / Q000009:adverse effects / Q000401:mortality*; D016208:Databases, Factual; D005260:Female; D017052:Hospital Mortality; D006801:Humans; D007036:Hypothermia, Induced / Q000009:adverse effects / Q000379:methods / Q000401:mortality*; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D016017:Odds Ratio; D065840:Protective Factors; D012189:Retrospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D012955:Societies, Medical; D013997:Time Factors; D016896:Treatment Outcome