title: The impact of mild induced hypothermia on the rate of transfusion and the mortality in severely injured patients: a retrospective multi-centre study.
abstract: BACKGROUND
  Although under discussion, induced hypothermia (IH) is an established therapy for patients with cardiac arrest or traumatic brain injuries. The influences on coagulopathy and bleeding tendency in severely injured patients (SIP) with concomitant traumatic brain injury are most widely unclear. Therefore, the aim of this study was to quantify the effect of mild IH in SIP with concomitant severe traumatic brain injuries on transfusion rate and mortality.
  
  
  METHODS
  In this retrospective multi-centre study, SIP from three European level-1 trauma centres with an ISS ≥16 between 2009 and 2011 were included. At hospital A, patients qualified for IH with age ≤70 years and a severe head injury with an abbreviated injury scale (AISHead) of ≥3. IH was defined as target core body temperature of 35 °C. Hypothermic patients were matched with two patients, one from hospital B and one from hospital C using age and AISHead. The effect of IH on the transfusion rate, complications and mortality was quantified with 95 % confidence intervals (CI). Patients not treated with IH in hospital A and those from hospital B and C, who were not matched, were used to adjust the CI for the effect of inter-hospital therapy protocol differences.
  
  
  RESULTS
  Mean age of patients in the IH-group (n = 43) was 35.7 years, mean ISS 30 points and sex distribution showed 83.7 % male. Mean age of matched patients in the normotherm-group (n = 86) was 36.7 years, mean ISS 33 points and there were 75.6 % males. For the hypothermic patients, we pointed out an estimate of mean difference for the number of transfused units of packed red blood cells as well as for mortality which does not indicate a decrease in the benefit gained by hypothermia. It is suggested that hypothermic patients tend to a higher rate of lung failure and thromboembolisms.
  
  
  CONCLUSIONS
  Though tending to an increased rate of complications, there is no evidence for a difference in both; rate of transfusion and mortality in SIP. Mild IH as an option for severe head injuries seems as well-being practicable in the presence of multiple severe injuries. Further, clinical studies regarding the side effects are necessary.
authors.affiliation: Division of Trauma Surgery, University Hospital Zurich, University of Zurich, Raemistrasse 100, 8091, Zurich, Switzerland. kaioliver.jensen@usz.ch.
authors.forename: Kai Oliver
authors.initials: KO
authors.lastname: Jensen
authors.affiliation: Department of Biostatistics, Institute for Epidemiology, Biostatistics and Prevention, University of Zurich, Zurich, Switzerland.
authors.forename: Leonhard
authors.initials: L
authors.lastname: Held
authors.affiliation: Department of Biostatistics, Institute for Epidemiology, Biostatistics and Prevention, University of Zurich, Zurich, Switzerland.
authors.forename: Andrea
authors.initials: A
authors.lastname: Kraus
authors.affiliation: Department of Orthopedic Trauma, University of Aachen, Aachen, Germany.
authors.forename: Frank
authors.initials: F
authors.lastname: Hildebrand
authors.affiliation: Trauma Department, Hannover Medical School, Hannover, Germany.
authors.forename: Philipp
authors.initials: P
authors.lastname: Mommsen
authors.affiliation: Division of Trauma Surgery, University Hospital Zurich, University of Zurich, Raemistrasse 100, 8091, Zurich, Switzerland.
authors.forename: Ladislav
authors.initials: L
authors.lastname: Mica
authors.affiliation: Division of Trauma Surgery, University Hospital Zurich, University of Zurich, Raemistrasse 100, 8091, Zurich, Switzerland.
authors.forename: Guido A
authors.initials: GA
authors.lastname: Wanner
authors.affiliation: Division of Surgical Intensive Care Medicine, University Hospital Zurich, University of Zurich, Zurich, Switzerland.
authors.forename: Peter
authors.initials: P
authors.lastname: Steiger
authors.affiliation: University Hospital Zurich, University of Zurich, Zurich, Switzerland.
authors.forename: Rudolf M
authors.initials: RM
authors.lastname: Moos
authors.affiliation: Division of Trauma Surgery, University Hospital Zurich, University of Zurich, Raemistrasse 100, 8091, Zurich, Switzerland.
authors.forename: Hans-Peter
authors.initials: HP
authors.lastname: Simmen
authors.affiliation: Division of Trauma Surgery, University Hospital Zurich, University of Zurich, Raemistrasse 100, 8091, Zurich, Switzerland.
authors.forename: Kai
authors.initials: K
authors.lastname: Sprengel
mesh_terms: D000328:Adult; D000368:Aged; D001803:Blood Transfusion; D000070642:Brain Injuries, Traumatic / Q000150:complications / Q000401:mortality* / Q000628:therapy*; D005260:Female; D006801:Humans; D007036:Hypothermia, Induced; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D016896:Treatment Outcome
keywords: Induced hypothermia; Mortality; Severely injured; Transfusion rate