title: Esophageal temperature after out-of-hospital cardiac arrest: an observational study.
abstract: BACKGROUND
  Out-of-hospital cardiac arrest (OHCA) is a significant cause of death and severe neurological disability. The only post-return of spontaneous circulation (ROSC) therapy shown to increase survival is mild therapeutic hypothermia (MTH). The relationship between esophageal temperature post OHCA and outcome is still poorly defined.
  
  
  METHODS
  Prospective observational study of all OHCA patients admitted to a single centre for a 14-month period (1/08/2008 to 31/09/2009). Esophageal temperature was measured in the Emergency Department and Intensive Care Unit (ICU). Selected patients had pre-hospital temperature monitoring. Time taken to reach target temperature after ROSC was recorded, together with time to admission to the Emergency Department and ICU.
  
  
  RESULTS
  164 OHCA patients were included in the study. 105 (64.0%) were pronounced dead in the Emergency Department. 59 (36.0%) were admitted to ICU for cooling; 40 (24.4%) died in ICU and 19 (11.6%) survived to hospital discharge. Patients who achieved ROSC and had esophageal temperature measured pre-hospital (n=29) had a mean pre-hospital temperature of 33.9 degrees C (95% CI 33.2-34.5). All patients arriving in the ED post OHCA had a relatively low esophageal temperature (34.3 degrees C, 95% CI 34.1-34.6). Patients surviving to hospital discharge were warmer on admission to ICU than patients who died in hospital (35.7 degrees C vs 34.3 degrees C, p<0.05). Patients surviving to hospital discharge also took longer to reach T(targ) than non-survivors (2h 48min vs 1h 32min, p<0.05).
  
  
  CONCLUSIONS
  Following OHCA all patients have esophageal temperatures below normal in the pre-hospital phase and on arrival in the Emergency Department. Patients who achieve ROSC following OHCA and survive to hospital discharge are warmer on arrival in ICU and take longer to reach target MTH temperatures compared to patients who die in hospital. The mechanisms of action underlying esophageal temperature and survival from OHCA remain unclear and further research is warranted to clarify this relationship.
authors.affiliation: Emergency Medicine, Royal Infirmary of Edinburgh, Little France Crescent, Edinburgh, United Kingdom. richardlyon@doctors.org.uk
authors.forename: R M
authors.initials: RM
authors.lastname: Lyon
authors.forename: S E
authors.initials: SE
authors.lastname: Richardson
authors.forename: A W
authors.initials: AW
authors.lastname: Hay
authors.forename: P J D
authors.initials: PJ
authors.lastname: Andrews
authors.forename: C E
authors.initials: CE
authors.lastname: Robertson
authors.forename: G R
authors.initials: GR
authors.lastname: Clegg
mesh_terms: D000328:Adult; D000368:Aged; D001831:Body Temperature / Q000502:physiology; D001833:Body Temperature Regulation / Q000502:physiology*; D016887:Cardiopulmonary Resuscitation / Q000379:methods* / Q000401:mortality; D015331:Cohort Studies; D003422:Critical Care / Q000379:methods; D004632:Emergency Medical Services / Q000379:methods*; D004947:Esophagus; D005500:Follow-Up Studies; D006323:Heart Arrest / Q000401:mortality / Q000628:therapy*; D017052:Hospital Mortality / Q000639:trends; D006801:Humans; D007036:Hypothermia, Induced / Q000379:methods*; D008297:Male; D008875:Middle Aged; D019370:Observation; D011237:Predictive Value of Tests; D011446:Prospective Studies; D016019:Survival Analysis; D013997:Time Factors; D016896:Treatment Outcome