Factors Associated with Delayed Cooling in Cardiac Arrest Patients

Therapeutic hypothermia has been shown to improve neurologic outcome in medical cardiac arrest patients, yet little is known about factors that delay target temperature achievement. Our primary aim was to identify factors associated with not achieving our institutional "door-to-cool" (DTC) performance goal (emergency department [ED] arrival to temperature of 34°C) of ≤4 hours. Secondary aims included whether achievement of DTC goal was associated with timing of bolus neuromuscular blockade (NMB), survival, or functional outcome. This was a retrospective cohort study of a medical cardiac arrest quality improvement (QI) database that included patients treated from November 2007 to August 2012. The database was queried for patient demographics, arrest characteristics, specific cooling techniques used, whether patients underwent emergent computed tomography imaging or cardiac catheterization, and patient outcomes. Logistic regression was used to assess the factors associated with DTC goal performance and outcomes. We enrolled 327 patients, median age 58, median return of spontaneous circulation (ROSC) time of 21 minutes (interquartile range [IQR] 14-29 minutes), and shockable initial rhythm in 61%. One hundred forty-four (44%) patients survived to hospital discharge, 133 (41%) with good functional outcome, as defined as cerebral performance category 1-2. Induction with cold IV fluids [OR 0.50 (CI: 0.29-0.85)] and NMB administration within 2 hours of ED arrival [OR 2.95 (CI: 1.17-7.43)] was associated with achieving DTC goal. Logistic regression showed that achievement of DTC goal ≤4 hours [OR 0.59 (0.32-1.09)] was not associated with good functional outcome. In our single-center cohort, initiation of cold intravenous fluids (IVF) and early NMB administration were associated with improved DTC goal performance of 4 hours. However, patients achieving DTC goals were not associated with improved outcomes.