Abstract 18656: The Effect of Targeted Temperature Management is Dependent Upon the Duration of Out-of-hospital Cardiac Arrest

Abstract

Introduction: Targeted temperature management (TTM) reduces neurologic injury from out-of-hospital cardiac arrest (OHCA). As the risk of neurologic injury increases with prolonged cardiac arrests, the benefit of TTM may depend upon cardiac arrest duration. We hypothesized that there is a time-dependent effect of TTM on neurologic outcomes from OHCA. Methods: Retrospective, observational study of the Toronto RescuNET Epistry-Cardiac Arrest database from 2007 to 2014. We included adult (>18) OHCA of presumed cardiac etiology that remained comatose (GCS<10) after a return of spontaneous circulation. We used multivariable logistic regression to determine the effect of TTM and the duration of cardiac arrest on good neurologic outcome (Modified Rankin Scale (mRS) 0-3) and survival to hospital discharge while controlling for other known predictors. Results: There were 1496 patients who met our inclusion criteria, of whom 981 (66%) received TTM. Of the patients who received TTM, 59% had a good neurologic outcome compared to 39% of patients who did not receive TTM (p< 0.001). After adjusting for the Utstein variables, use of TTM was associated with improved neurologic outcome (OR 1.60, 95% CI 1.10-2.32; p = 0.01) but not with survival to discharge (OR 1.23, 95% CI 0.90-1.67; p = 0.19). The impact of TTM on neurologic outcome was dependent on the duration of cardiac arrest (p<0.05) (Fig 1). Other significant predictors of good neurologic outcome were younger age, public location, initial shockable rhythm, and shorter duration of cardiac arrest (all p values < 0.05). A subgroup analysis found the use of TTM to be associated with neurologic outcome in both shockable (p = 0.01) and non-shockable rhythms (p = 0.04) but was not associated with survival to discharge in either group (p = 0.12 and p = 0.14 respectively). Conclusion: The use of TTM was associated with improved neurologic outcome at hospital discharge. Patients with prolonged durations of cardiac arrest benefited more from TTM.