Elsevier

Resuscitation

Volume 85, Issue 2, February 2014, Pages 211-214
Resuscitation

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

https://doi.org/10.1016/j.resuscitation.2013.10.030Get rights and content

Abstract

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 °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 °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 °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.

Introduction

Over the past decade there have been major advances in post-resuscitation care following successful resuscitation from out-of-hospital cardiac arrest (OHCA). Use of therapeutic hypothermia (TH) in patients who present in a comatose state to the hospital has positively impacted the number of patients who survive with a favorable neurologic outcome.1, 2 However, little is known about the effect of TH on predicting who will ultimately regain consciousness and the time course to awakening. Further, the practice parameters for outcome prediction promulgated by the American Academy of Neurology (AAN) in 2006 pre-date the broad adoption of TH.3, 4

Recent retrospective and prospective studies indicate that TH and sedation influence neurologic examination and biochemical markers of recovery.5, 6 In the absence of reliable serum and clinical indicators we retrospectively analyzed time to awakening in all of our cardiac arrest survivors between 2006 and 2010. We sought to identify some distinguishing features of those who awoke >72 h following cardiac arrest (“late awakeners”).

Section snippets

Methods

St. Cloud Hospital (St. Cloud, MN, USA) is a community-based hospital that serves a population of ∼500,000 people in central Minnesota, USA. Since January 2006, it has been the clinical policy to treat all resuscitated OHCA patients with TH for 24 h if they were comatose upon intensive care unit admission or were unable to respond intelligibly.7 TH was administered as part of a protocol by Intensive Care Unit physicians and nurses that included ventilator support, sedation, paralysis to prevent

Statistical analysis

Due to the non-Gaussian distribution, data are reported as medians, interquartile range [IQR] and absolute range (range). Comparisons between groups were performed by the χ2 test or Fisher's exact test for categorical variables and by the Mann–Whitney U test or Kruskal–Wallis test to compare continuous variables within groups. To investigate correlation between continuous variables, Spearman's rho correlation test was performed. All analyses were 2 sided, and p values <0.05 were considered

Results

Between January 1, 2006 and December 21, 2010, 442 patients were moved to St. Cloud hospital after sustaining cardiac arrest (Fig. 1). A total of 257 patients were excluded as they died prior to hospital discharge whereas 185 patients were discharged alive. Of the 185 survivors, 96 patients were sufficiently awake upon arrival to the intensive care unit so they did not meet the TH protocol inclusion criteria. A total of 89 patients were treated with TH as they were comatose or could only

Discussion

Little is known about how long to pursue aggressive medical management in OHCA patients treated with TH once rewarming is completed. Neurological physical examinations are challenging when these patients remain persistently unresponsive, especially after a prolonged period of sedation. Neurological examinations have not been reported to be predictive of who will ultimately regain consciousness.3, 8, 9, 10, 11 There are many proposed markers of poor prognosis; the absence of the pupillary light

Conflict of interest statement

No conflicts of interest to declare.

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A Spanish translated version of the summary of this article appears as Appendix in the final online version at http://dx.doi.org/10.1016/j.resuscitation.2013.10.030.

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