Abstract 230: Targeted Temperature Management: Exploring the Association Between Processes of Care and Outcomes After Out-of-Hospital Cardiac Arrest

Abstract

Introduction: Randomized trials have demonstrated that Targeted Temperature Management (TTM) improves functional survival in patients after out-of-hospital cardiac arrest (OHCA). However, the optimal process of implementation and delivery remains unclear, specifically how fast, how cold or how long to cool. The objective of this study was to evaluate the association of these processes of care with survival and neurological function in patients after OHCA. METHODS: We conducted a retrospective cohort study on consecutive adult (≥18 years) non-traumatic OHCA patients from November 1, 2007 to January 31, 2012. Eligible patients who were treated with TTM after return of spontaneous circulation were included. The primary and secondary outcomes were in-hospital survival and good neurological status (Modified Rankin Scale of 0-3) at hospital discharge, respectively. Bivariate and generalized estimating equation analyses were used to evaluate the associations between processes of care variables and patient outcomes. Results: There were 5770 consecutive OHCA patients, of whom 747 (12.9%) patients were eligible and received TTM; 365 (48.9%) patients survived to hospital discharge, of whom 241 (66.0%) patients had good neurological outcomes. After adjusting for the Utstein variables, a higher temperature prior to cooling was associated with improved survival [OR 1.26 per °C, 95% CI 1.09-1.46, p=0.002] and neurological outcomes [OR 1.27 per °C, 95% CI 1.08-1.50, p=0.004]. Moreover, a slower rate of cooling was associated with improved survival [OR 0.73 per °C/hr, 95% CI 0.54-1.00, p=0.05] and neurological outcomes [OR 0.74 per °C/hr, 95% CI 0.57-0.97, p=0.03]. The location of cooling initiation, coldest temperature, and cold duration ≤34°C were not associated with outcomes. CONCLUSION: A higher baseline temperature prior to cooling and a slower rate of cooling were associated with both improved survival and neurological outcomes. This may reflect the complex relationship between the extent of brain injury causing hypothalamic dysfunction and impaired thermoregulation, and the cooling techniques used in patients after cardiac arrest.