title: The impact of downtime on neurologic intact survival in patients with targeted temperature management after out-of-hospital cardiac arrest: National multicenter cohort study.
abstract: The association between long duration of resuscitation efforts in out-of-hospital cardiac arrest (OHCA) and neurologic outcome is unclear and understudied with advancements in post-cardiac arrest care and high-quality cardiopulmonary resuscitation. We investigated how downtime, defined as the interval from collapse-to-return of spontaneous circulation (ROSC), impacts on neurologic outcome in OHCA patients treated with targeted temperature management (TTM).
  
  
  
  A multicenter, registry-based, retrospective cohort study was conducted using cases from 24 hospitals across South Korea. Of the 930 adults (≥18 years) non-traumatic OHCA patients treated with TTM between January 2007 and December 2012 at these hospitals, we included 858 patients who had sufficient data for calculating downtime. Good neurologic outcome was defined as a cerebral performance category score of 1 or 2.
  
  
  
  Median downtime was 30.0 (22.0-41.0min) and 242 patients (28.2%) had good neurologic outcome. When downtime was divided by 10-min intervals (≤10min, 11-20min, 21-30min, 31-40min, 41-50min, 51-60min, and >60min), their neurologically intact survival rate were 48.2%, 51.6%, 29.2%, 22.1%, 16.1%, 14.8%, and 7.1%, respectively (p=0.01). Although downtime was associated with poor neurologic outcome [odds ratio 1.06 (1.05-1.08), p<0.01], the area under the receiver operating characteristic curve of downtime for outcome was only 0.67, 95% CI (0.63-0.71). Furthermore, even with downtime >20min, 22.2% (150/526) patients still had a good neurologic outcome, and this percentage increased to 50.3% (93/185) in patients with an initial shockable rhythm, and 31.1% (134/431) with age <65 years.
  
  
  
  We found that neurologically intact survival can occur at prolonged downtimes and were unable to identify a downtime for which survivability was clearly futile. These data suggest that downtime should not be considered as a factor in determining whether to provide aggressive post-arrest care, especially in patients with young patients or those with an initially shockable rhythm.
authors.affiliation: Department of Emergency Medicine, Ulsan University College of Medicine, Asan Medical Center, Seoul, Republic of Korea; Department of Emergency Medicine, Beth Israel Deaconess Medical Center, Boston, MA, USA. Electronic address: wonpia73@naver.com.
authors.forename: Won Young
authors.initials: WY
authors.lastname: Kim
authors.affiliation: Department of Emergency Medicine, Ulsan University College of Medicine, Asan Medical Center, Seoul, Republic of Korea.
authors.forename: Shin
authors.initials: S
authors.lastname: Ahn
authors.affiliation: Department of Emergency Medicine, Ulsan University College of Medicine, Ulsan, Republic of Korea.
authors.forename: Jung Seok
authors.initials: JS
authors.lastname: Hong
authors.affiliation: Department of Emergency Medicine, College of Medicine, Hallym University, Seoul, Republic of Korea.
authors.forename: Gyu Chong
authors.initials: GC
authors.lastname: Cho
authors.affiliation: Department of Emergency Medicine, Ulsan University College of Medicine, Asan Medical Center, Seoul, Republic of Korea.
authors.forename: Dong Woo
authors.initials: DW
authors.lastname: Seo
authors.affiliation: Department of Emergency Medicine, College of Medicine, Chonnam National University, Gwangju, Republic of Korea.
authors.forename: Kyung Woon
authors.initials: KW
authors.lastname: Jeung
authors.affiliation: Department of Emergency Medicine, The Catholic University of Korea, Seoul, Republic of Korea.
authors.forename: Young-Min
authors.initials: YM
authors.lastname: Kim
authors.affiliation: Department of Emergency Medicine, The Catholic University of Korea, Seoul, Republic of Korea.
authors.forename: Kyu Nam
authors.initials: KN
authors.lastname: Park
authors.affiliation: Department of Emergency Medicine, Beth Israel Deaconess Medical Center, Boston, MA, USA.
authors.forename: Katherine
authors.initials: K
authors.lastname: Berg
authors.affiliation: Department of Emergency Medicine, Beth Israel Deaconess Medical Center, Boston, MA, USA.
authors.forename: Michael W
authors.initials: MW
authors.lastname: Donnino
mesh_terms: D000368:Aged; D016887:Cardiopulmonary Resuscitation / Q000009:adverse effects*; D016208:Databases, Factual; D005260:Female; D006801:Humans; D007036:Hypothermia, Induced / Q000706:statistics & numerical data*; D008297:Male; D018447:Medical Futility; D008875:Middle Aged; D058687:Out-of-Hospital Cardiac Arrest / Q000401:mortality / Q000628:therapy*; D012372:ROC Curve; D012189:Retrospective Studies; D013997:Time Factors; D016896:Treatment Outcome
keywords: Hypothermia; Out-of-hospital cardiac arrest; Outcome; Resuscitation