title: Unintentional perioperative hypothermia is associated with severe complications and high mortality in elective operations.
abstract: BACKGROUND
  Hypothermia occurs in as many as 7% of elective colorectal operations and is an underestimated risk factor for complications and death. Rewarming of hypothermic patients alone is not sufficient to prevent such adverse events. We investigated the outcomes of patients who became hypothermic (<35°C) after elective operations and compared them with closely matched, nonhypothermic operative patients to better define the impact of hypothermia on surgical outcomes, as well as to identify independent risk factors for hypothermia.
  
  
  METHODS
  We queried the University HealthSystem Consortium (UHC) database for elective operative patients who became unintentionally hypothermic from October 2008 to March 2012, and identified 707 patients. Exclusion criteria were deliberate hypothermia, age <18 years, or death on day of admission. Separately, to validate the accuracy of hypothermia coding, we reviewed the hospital charts of all University of Louisville Hospital patients with hypothermia whose data were submitted to UHC.
  
  
  RESULTS
  All patients from UHC with a code for hypothermia were indeed unintentionally hypothermic. Hypothermic patients undergoing elective operations experienced a 4-fold increase in mortality (17.0% vs 4.0%; P < .001) and a doubled complication rate (26.3% vs 13.9%; P < .001), in which sepsis and stroke increased the most. Several independent risk factors for hypothermia were amenable to preoperative improvement: anemia, chronic renal impairment, and unintended weight loss. Severity of illness on admission, age >65 years, male sex, and neurologic disorders also were risk factors.
  
  
  CONCLUSIONS
  Hypothermia is associated with an increased rate of mortality and complications. Preventive treatment of these risk factors before operation and aggressive warming measures in the "at risk" population may decrease hypothermia-related morbidity and mortality in elective operations. Randomized-controlled trials should be conducted to evaluate the impact of aggressive warming measures in the at-risk population.
authors.affiliation: Hiram C. Polk Jr. MD Department of Surgery, University of Louisville School of Medicine, Louisville, KY; University of Louisville Hospital, Louisville, KY. Electronic address: adrianbilleter@gmail.com.
authors.forename: Adrian T
authors.initials: AT
authors.lastname: Billeter
authors.affiliation: University HealthSystem Consortium, Chicago, IL.
authors.forename: Samuel F
authors.initials: SF
authors.lastname: Hohmann
authors.affiliation: Hiram C. Polk Jr. MD Department of Surgery, University of Louisville School of Medicine, Louisville, KY; University of Louisville Hospital, Louisville, KY.
authors.forename: Devin
authors.initials: D
authors.lastname: Druen
authors.affiliation: Hiram C. Polk Jr. MD Department of Surgery, University of Louisville School of Medicine, Louisville, KY; University of Louisville Hospital, Louisville, KY.
authors.forename: Robert
authors.initials: R
authors.lastname: Cannon
authors.affiliation: Hiram C. Polk Jr. MD Department of Surgery, University of Louisville School of Medicine, Louisville, KY; University of Louisville Hospital, Louisville, KY. Electronic address: hcpolk01@louisville.edu.
authors.forename: Hiram C
authors.initials: HC
authors.lastname: Polk
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D017558:Elective Surgical Procedures / Q000009:adverse effects* / Q000401:mortality; D005260:Female; D006801:Humans; D007035:Hypothermia / Q000150:complications* / Q000401:mortality / Q000517:prevention & control; D007629:Kentucky / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications / Q000209:etiology* / Q000401:mortality / Q000517:prevention & control; D012189:Retrospective Studies; D055815:Young Adult