Elsevier

Resuscitation

Volume 125, April 2018, Pages 56-65
Resuscitation

Clinical paper
Cooling methods of targeted temperature management and neurological recovery after out-of-hospital cardiac arrest: A nationwide multicenter multi-level analysis

https://doi.org/10.1016/j.resuscitation.2018.01.043Get rights and content

Abstract

Objective

The purpose of this study was to determine whether the cooling method used for target temperature management (TTM) was associated with neurological recovery after out-of-hospital cardiac arrest (OHCA).

Methods

From January 2008 to December 2016, adult OHCA patients who survived to hospitalization without any traumatic etiology and who received TTM were included. Patients who did not have information about neurological status at hospital discharge or who did not have information on target temperature management were excluded. Cooling methods were classified into four groups: (1) external device cooling (EDC) using a pad with cooling device, (2) external conventional cooling (ECC) such as ice water, fans, and simple blankets, (3) Intravascular cooling (IVC) using an intravascular cooling catheter, and (4) intracavitary cooling (ICC) using ice water for washing cavitary organ. The outcomes were good cerebral performance scale (CPC) score 1 or 2 and survival to discharge. In multivariate logistic regression analysis, the adjusted odds ratios (AORs) and the 95% confidence intervals (CIs) were calculated (reference = ECC). Finally, we used a GLIMMIX procedure with group-level variables (hospitals) to create a multilevel model for adjusting the clustering factor of patients being treated in the same hospital.

Results

The final analysis included a total of 4246 eligible patients (ECC 1386, EDC 2107, IVC 376, ICC 377). Good neurologic recovery was 20.7% for all (ECC 17.4, EDC 23.1%, IVC 26.9%, and ICC 13.3%, p < .001). The survival rate was 46.4% for all (ECC 45.4%, EDC 48.5%, IVC 50.5%, ICC 34.2%, p < .001). There were no significant differences (AOR and 95% CI) in the multi-level analysis for good neurological recovery between cooling methods compared with ECC; EDC 1.20 (0.95–1.52), IVC 1.43 (0.90–2.27), and ICC 0.71 (0.46–1.10). The ICC group had a lower survival to discharge rate compared with ECC; EDC 0.97 (0.83–1.15), IVC 0.96 (0.78–1.19), and ICC 0.63 (0.43–0.85).

Conclusion

The cooling methods for TTM did not show any significant difference in neurological recovery in multi-level logistic regression analysis. Only intracavitary cooling resulted in a lower survival to discharge than external surface cooling.

Introduction

Severe neurologic injury after cardiopulmonary resuscitation (CPR) in out-of-hospital cardiac arrest (OHCA) patients has been known to be the most common cause of death [1]. The formation of free radicals and other mediators in the reperfusion phase can cause a neurologic injury cascade [2]. Although several randomized controlled trials attempted and failed to show significant improvement by specific medical interventions [[3], [4], [5]], targeted temperature management (TTM) has shown improvement in outcomes as a neuroprotective treatment in post-resuscitation care [[6], [7]].

The potential mechanisms of TTM that improve neurologic outcomes are as follows: a lower cerebral metabolic rate for oxygen, suppression of the chemical reaction associated with reperfusion injury, or activation of anti-apoptotic mechanisms via cooling or control of the temperature using specific methods [[8], [9]]. Those TTM methods were divided into the following four main categories according to the approach to cooling: 1) external conventional cooling (ECC), 2) external device cooling (EDC), 3) intravascular cooling (IVC), and 4) intracavitary (ICC) cooling [10]. ECC, such as crushed ice or an ice bag, have the disadvantage of unintentional cooling below the target temperature, which can have deleterious effects and is less effective in maintaining temperature [[11], [12]]. Maintenance of temperature is difficult and shivering is more common in this method of cooling. [13]. Although IVC showed a similar effect on outcome compared to EDC [[14], [15], [16], [17]], adverse events can occur, such as a catheter-related bloodstream infection, venous thrombosis, and vascular procedure-related complications [[16], [18]]. IVC and EDC methods incorporate more advanced technology and provide easy operation for maintaining temperature; however, these methods are more expensive than conventional cooling methods such as ECC or ICC.

Few studies have compared the effects of the four different types of cooling methods on outcomes. We hypothesized that the cooling methods for TTM are associated with outcomes after OHCA. This study aimed to compare the effect among the four cooling method groups for TTM on neurological outcomes after OHCA.

Section snippets

Methods

The study was approved by the Institutional Review Board at the research site, and the Korea Center for Disease Control and Prevention (CDC) approved the use of the data in this study.

Study design and setting

The study is a cross-sectional analysis using a nationwide OHCA registry. The study was performed in Korea, which has a population of 50 million people. Single-tiered and government-based emergency medical services (basic-to-intermediate level) are supported by 17 provincial fire departments with a total of 1400 ambulance stations. Emergency medical technicians provide basic life support and the use of an automatic defibrillator for OHCA patients in the field and transport all patients to the

Demographic findings

From the 4886 eligible OHCA patients who received TTM, the following patients were excluded: patients younger than 18 years of age at the time of cardiac arrest (N = 109), patients with traumatic cause of arrest (N = 134), and patients with unknown cooling method (N = 397). The remaining 4246 patients were included in the final analysis. (Fig. 1) The total number of TTMs decreased, but the number of EDCs increased and was relatively larger than the number of ECCs, IVCs, and ICCs. (Fig. 2)

Of the

Discussion

The study found that there were no significant differences in neurological recovery after OHCA by three TTM cooling methods (ECC, EDC, and IVC) except only intracavitary cooling method in entire patient dataset. The findings were consistent in the subgroups that had information for propensity score-matched samples that were extracted to be comparable for risk factors between cooling methods.

The cooling methods showed similar clinical outcomes, although the cooling methods were very different in

Conclusion

In this study, using multilevel analysis of the OHCA database population, there was no significant difference in good neurologic recovery among the four cooling methods (external device cooling, intravascular device cooling, intracavitary cooling compared to external conventional cooling). Individual comparisons between the two TTM methods using propensity score matched samples showed poor neurological recovery from external device cooling (rather than external conventional cooling) and poor

Conflict of interest

There are no conflicts of interest for all authors in this study.

Acknowledgments

The study was funded by the Korea Centers for Disease Control and Prevention (CDC). The Korea CDC and National Emergency Management Agency (national fire department) have been collaborating to collect OHCA data.

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    A Spanish translated version of the abstract of this article appears as Appendix in the final online version at https://doi.org/10.1016/j.resuscitation.2018.01.043.

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