Awakening after cardiac arrest and post resuscitation hypothermia: Are we pulling the plug too early?

Background: Time to awakening after out-of-hospital cardiac arrest (OHCA) and post-resuscitation therapeutic hypothermia (TH) varies widely. We examined the time interval from when comatose OHCA patients were rewarmed to 37 degrees C to when they showed definitive signs of neurological recovery and tried to identify potential predictors of awakening. Methods: With IRB approval, a retrospective case study was performed in OHCA patients who were comatose upon presentation to a community hospital during 2006-2010. They were treated with TH (target of 33 degrees C) for 24 h, rewarmed, and discharged alive. Comatose patients were generally treated medically after TH for at least 48 h before any decision to withdraw supportive care was made. Pre-hospital TH was not used. Data are expressed as medians and interquartile range. Results: The 89 patients treated with TH in this analysis were divided into three groups based upon the time between rewarming to 37 degrees C and regaining consciousness. The 69 patients that regained consciousness in = 48 h after rewarming were termed "early-awakeners". Ten patients regained consciousness 48-72 h after rewarming and were termed "intermediate-awakeners". Ten patients remained comatose and apneic >72 h after rewarming but eventually regained consciousness; they were termed "late-awakeners". The ages for the early, intermediate and late awakeners were 56 [49,65], 62 [48,74], and 58 [55,65] years, respectively. Nearly 67% were male. Following rewarming, the time required to regain consciousness for the early, intermediate and late awakeners was 9 [2,18] (range 0-47), 60.5 [56,64.5] (range 49-71), and 126 [104,151] h (range 73-259), respectively. Within 90 days of hospital admission, favorable neurological function based on a Cerebral Performance Category (CPC) score of 1 or 2 was reported in 67/69 early, 10/10 intermediate, and 8/10 late awakeners. Conclusion: Following OHCA and TH, arbitrary withdrawal of life support <48 h after rewarming may prematurely terminate life in many patients with the potential for full neurological recovery. Additional clinical markers that correlate with late awakening are needed to better determine when withdrawal of support is appropriate in OHCA patients who remain comatose >48 h after rewarming. (C) 2013 Elsevier Ireland Ltd. All rights reserved.