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Abstract

Introduction: Induced hypothermia (IH) to 32-34°C is a recommended component of post cardiac arrest care. The impact of IH on outcome is well documented with shockable ventricular rhythms (VT/VF), but less clear with pulseless electrical activity (PEA) or asystole (AS). IH has been implemented for all unresponsive post arrest patients, without regard to arrest location or rhythm, at our institution since 2008. Methods: A retrospective review of all unresponsive post cardiac arrest patients treated with IH was done. We included all in-hospital arrests (IHCA) and out-of hospital arrests (OHCA) from 2009-2012. Per protocol post-arrest IH was initiated in the emergency department for OHCA and in the intensive care unit for IHCA. Withdrawal of support & disposition was left to the discretion of the admitting team. We analyzed patient demographics, peri-arrest and treatment variables, survival to discharge, and neurologic outcome data for all patients. Good neurologic outcome (GNO) was defined as a cerebral performance category of 1- 2 assessed at discharge. Results: 580 patients who underwent IH were included: 478 OHCA (82.4%), 102 IHCA. VT/VF was the initial rhythm for 194 patients and 386 had PEA/AS (66.6%). Mean ROSC to goal temp was 284.7 ± 4.04 minutes (min) and mean IH initiation to goal temp was 179.7 ± 12.4 min. Within group survival was 42.9% for OHCA and 45.1% for IHCA; 63.9% for VT/VF and 32.9% PEA/AS. Overall survival with GNO was 31.3% (32.6% OHCA, 25.5% IHCA). Survival with GNO for VT/VF was 54.6% (56% of OHCA, 38.8% of IHCA) and 19.7% for PEA/AS (18.9% of OHCA, 22.6% of IHCA). For survivors to discharge (N=124 VT/VF, N=127 PEA/AS), 85% of VT/VF and 59.8% of PEA/AS survivors had GNO. The odds ratio [OR] for GNO among VT/VF survivors was 3.95 (95% CI 2.14- 7.29, p < 0.0001) compared with PEA/AS survivors, OR 0.25 (0.14-0.47, p < 0.0001). Conclusions: We conclude that PEA/AS is a more frequently encountered initial rhythm for both OHCA and IHCA and that survival with GNO is achievable. While survival with GNO is less with PEA/AS, the trend for improved GNO with IH appears to be better than reported in the historical literature (7-12% survival; 1.7-10% with GNO).