title: Seasonal variability and influence of outdoor temperature on body temperature of cardiac arrest victims.
abstract: OBJECTIVE
  Mild therapeutic hypothermia is a major advance in post-resuscitation-care. Some questions remain unclear regarding the time to initiate cooling and the time to achieve target temperature below 34 °C. We examined whether seasonal variability of outside temperature influences the body temperature of cardiac arrest victims, and if this might have an effect on outcome.
  
  
  METHODS
  Patients with witnessed out-of-hospital cardiac arrests were enrolled retrospectively. Temperature variables from 4 climatic stations in Vienna were provided from the Central Institute for Meteorology and Geodynamics. Depending on the outside temperature at the scene the study participants were assigned to a seasonal group. To compare the seasonal groups a Student's t-test or Mann-Whitney U test was performed as appropriate.
  
  
  RESULTS
  Of 134 patients, 61 suffered their cardiac arrest during winter, with an outside temperature below 10 °C; in 39 patients the event occurred during summer, with an outside temperature above 20 °C. Comparing the tympanic temperature recorded at hospital admission, the median of 36 °C (IQR 35.3-36.3) during summer differed significantly to winter with a median of 34.9 °C (IQR 34-35.6) (p<0.05). This seasonal alterations in core body temperature had no impact on the time-to-target-temperature, survival rate or neurologic recovery.
  
  
  CONCLUSIONS
  The seasonal variability of outside temperature influences body temperature of out-of-hospital cardiac arrest victims.
authors.affiliation: Department of Emergency Medicine, Medical University of Vienna, Vienna, Austria.
authors.forename: Peter
authors.initials: P
authors.lastname: Stratil
authors.forename: Christian
authors.initials: C
authors.lastname: Wallmueller
authors.forename: Andreas
authors.initials: A
authors.lastname: Schober
authors.forename: Mathias
authors.initials: M
authors.lastname: Stoeckl
authors.forename: David
authors.initials: D
authors.lastname: Hoerburger
authors.forename: Christoph
authors.initials: C
authors.lastname: Weiser
authors.forename: Christoph
authors.initials: C
authors.lastname: Testori
authors.forename: Danica
authors.initials: D
authors.lastname: Krizanac
authors.forename: Alexander
authors.initials: A
authors.lastname: Spiel
authors.forename: Thomas
authors.initials: T
authors.lastname: Uray
authors.forename: Fritz
authors.initials: F
authors.lastname: Sterz
authors.forename: Moritz
authors.initials: M
authors.lastname: Haugk
mesh_terms: D000368:Aged; D001317:Austria; D001831:Body Temperature / Q000502:physiology*; D016887:Cardiopulmonary Resuscitation / Q000379:methods* / Q000401:mortality; D057231:Climate Change; D015331:Cohort Studies; D005260:Female; D006801:Humans; D007036:Hypothermia, Induced / Q000379:methods* / Q000401:mortality; D008297:Male; D008875:Middle Aged; D058687:Out-of-Hospital Cardiac Arrest / Q000401:mortality / Q000503:physiopathology* / Q000628:therapy; D012189:Retrospective Studies; D012621:Seasons; D015996:Survival Rate; D013696:Temperature; D013997:Time Factors; D016896:Treatment Outcome