title: Relation of intraoperative temperature to postoperative mortality in open colon surgery--an analysis of two randomized controlled trials.
abstract: BACKGROUND
  The open surgical wound is exposed to cold and dry ambient air resulting in heat loss mainly through radiation and convection. This cools the wound and promotes local vasoconstriction and hypoxia. Carbon dioxide (CO2) and water vapor are greenhouse gases with a warming effect. The aim was to evaluate if warm humidified CO2 insufflated in surgical wound can affect long-term overall mortality
  
  
  METHODS
  This is a retrospective study of two clinical trials, where patients were randomized to warm humidified CO2 (n = 80) or not (n = 78). All patients underwent elective major open colon surgery. Patients in the treatment group received insufflation of warm humidified CO2 into the open wound cavity via a gas diffuser to create a local atmosphere of 100% CO2. Temperature in the wound cavity was measured with a heat-sensitive infrared camera. Core temperature was measured at the tympanic membrane. Median follow-up was 70.9 months.
  
  
  RESULTS
  A multivariate analysis adjusted for age (p = 0.001) and cancer (p = 0.165) showed that the larger the temperature difference between final core temperature and wound edge temperature, the lower the overall survival rate (p = 0.050). Patients receiving insufflation of warm humidified CO2 had a tendency to a better overall survival compared with control patients (p = 0.508). End-of-operation wound edge temperature was negatively associated with mortality (OR = 0.80, 95% CI = 0.68-0.95, p = 0.011), whereas mortality was positively associated with age (10-year increase, OR = 1.78, 95% CI = 1.37-2.33, p < 0.001) and cancer (OR = 8.1, 95% CI = 1.95-33.7, p = 0.004).
  
  
  CONCLUSIONS
  A small end-of-operation temperature difference between final core and wound edge temperature was positively associated with patient survival in open colon surgery.
authors.affiliation: Department of Cardiothoracic Surgery and Anesthesiology, Karolinska Institute, Karolinska University Hospital, Stockholm, Sweden. joana.frey@ki.se.|Department of Molecular Medicine and Surgery, Karolinska Institute, Karolinska University Hospital, Stockholm, Sweden. joana.frey@ki.se.
authors.forename: J
authors.initials: J
authors.lastname: Frey
authors.affiliation: Department of Cardiothoracic Surgery and Anesthesiology, Karolinska Institute, Karolinska University Hospital, Stockholm, Sweden.|Department of Molecular Medicine and Surgery, Karolinska Institute, Karolinska University Hospital, Stockholm, Sweden.
authors.forename: M
authors.initials: M
authors.lastname: Holm
authors.affiliation: Department of Clinical Sciences, Interventions and Technology; Division of Surgery, Karolinska Institute; Karolinska University Hospital, Stockholm, Sweden.
authors.forename: M
authors.initials: M
authors.lastname: Janson
authors.affiliation: Department of Clinical Sciences, Interventions and Technology; Division of Surgery, Karolinska Institute; Karolinska University Hospital, Stockholm, Sweden.
authors.forename: M
authors.initials: M
authors.lastname: Egenvall
authors.affiliation: Department of Cardiothoracic Surgery and Anesthesiology, Karolinska Institute, Karolinska University Hospital, Stockholm, Sweden.|Department of Molecular Medicine and Surgery, Karolinska Institute, Karolinska University Hospital, Stockholm, Sweden.
authors.forename: J
authors.initials: J
authors.lastname: van der Linden
mesh_terms: D002245:Carbon Dioxide / Q000494:pharmacology; D015331:Cohort Studies; D003106:Colon / Q000601:surgery*; D003710:Demography; D013505:Digestive System Surgical Procedures / Q000401:mortality*; D023381:Endpoint Determination; D005260:Female; D006801:Humans; D007430:Intraoperative Care; D008297:Male; D008875:Middle Aged; D011184:Postoperative Period; D016016:Proportional Hazards Models; D016032:Randomized Controlled Trials as Topic; D013696:Temperature
chemical_list: D002245:Carbon Dioxide
keywords: Carbon dioxide; Colon cancer; Surgery; Survival; Temperature