Elsevier

Resuscitation

Volume 81, Issue 1, January 2010, Pages 9-14
Resuscitation

Clinical paper
A randomized controlled trial comparing the Arctic Sun to standard cooling for induction of hypothermia after cardiac arrest

https://doi.org/10.1016/j.resuscitation.2009.09.015Get rights and content

Abstract

Context

Hypothermia improves neurological outcome for comatose survivors of out-of-hospital cardiac arrest. Use of computer controlled high surface area devices for cooling may lead to faster cooling rates and potentially improve patient outcome.

Objective

To compare the effectiveness of surface cooling with the standard blankets and ice packs to the Arctic Sun, a mechanical device used for temperature management.

Design, setting, and patients

Multi-center randomized trial of hemodynamically stable comatose survivors of out-of-hospital cardiac arrest.

Intervention

Standard post-resuscitative care inducing hypothermia using cooling blankets and ice (n = 30) or the Arctic Sun (n = 34).

Main outcome measures

The primary end point was the proportion of subjects who reached a target temperature within 4 h of beginning cooling. The secondary end points were time interval to achieve target temperature (34 °C) and survival to 3 months.

Results

The proportion of subjects cooled below the 34 °C target at 4 h was 71% for the Arctic Sun group and 50% for the standard cooling group (p = 0.12). The median time to target was 54 min faster for cooled patients in the Arctic Sun group than the standard cooling group (p < 0.01). Survival rates with good neurological outcome were similar; 46% of Arctic Sun patients and 38% of standard patients had a cerebral performance category of 1 or 2 at 30 days (p = 0.6).

Conclusions

While the proportion of subjects reaching target temperature within 4 h was not significantly different, the Arctic Sun cooled patients to a temperature of 34 °C more rapidly than standard cooling blankets.

Trial registration

ClinicalTrials.gov NCT00282373, registered January 24, 2006.

Introduction

Induction of mild hypothermia (a core temperature of 32–34 °C) improves neurological outcome in comatose survivors of out-of-hospital cardiac arrest.1 This therapy is being adopted around the world, with most centers utilizing simple external cooling devices such as cooling blankets and ice bags.2 However, these simple methods of cooling, while easy to implement, were not specifically designed for rapid cooling of critically ill patients and do not provide precision body temperature control during maintenance and reversal of hypothermia.

The Arctic Sun® (Medivance Corp, Louisville, CO) is a United States Food and Drug Administration cleared temperature management system. It differs from standard cooling blankets by: (1) producing higher cold fluid flow rates, (2) utilizing conductive, adherent gel pads, and (3) implementing a precise temperature feedback-control mechanism. These factors may allow a more rapid induction of cooling and improved control of temperature during hypothermia maintenance and rewarming than standard cooling blankets.

The objective of this study was to compare the Arctic Sun to standard cooling blankets and ice bags for induction and maintenance of therapeutic hypothermia after cardiac arrest. We hypothesized that a greater proportion of patients would reach target temperature within 4 h when cooled with the Arctic Sun device as compared to patients cooled by standard cooling blankets. We further hypothesized that the Arctic Sun would cool patients faster and would improve the maintenance of patients within the therapeutic target range (32–34 °C), with less out of the target range temperature fluctuations when compared to standard cooling.

Section snippets

Methods

This was a multi-center randomized controlled trial. Patients were assigned to hypothermic treatment with either the Arctic Sun or standard cooling blankets by a centralized telephone system which utilized a fixed block randomization scheme with an allocation ratio of 1:1 for each center. Six university-affiliated hospitals participated. All hospitals had protocols for cooling post-cardiac arrest patients, but their experience ranged from 0 to 15 patients prior to the study. Most centers had

Results

Sixty-four patients were enrolled between November 2004 and March 2007. Thirty patients were randomized to standard cooling blankets, and thirty-four patients were randomized to the Arctic Sun. Three patients were removed from the protocol after randomization but before initiation of cooling: one in the Arctic Sun arm was removed because a CT scan obtained showed a subarachnoid hemorrhage; one patient in the Arctic Sun group was removed after family withdrew care after initially consenting to

Discussion

The Arctic Sun and standard cooling blankets were both effective at cooling comatose patients resuscitated from cardiac arrest. We were able to reach 33.9 °C in all cooled patients by 18 h and in 90% of subjects by 6.5 h following initiation of the therapy. This was substantially better than the HACA study where almost 20% of patients never reached their target temperature.3 The Arctic Sun cooled patients more rapidly than standard cooling blankets, with a median time to target temperature almost

Conflict of interest statement

Dr. Paradis has acted as a paid consultant to Medivance Inc. All authors received research support for the performance of the study from Medivance Inc.

Acknowledgements

This study was supported by a research grant from Medivance Incorporated to each institution. Medivance assisted with the study design and training of the investigators. The data were collected at the sites by the investigators and centrally tabulated by Medical Device Consultants, Inc. Medivance reviewed the final manuscript but did not make the final determination of publication. The final manuscript was approved by all authors. The project described was supported in part by Award Number

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A Spanish translated version of the abstract of this article appears as Appendix in the final online version at doi:10.1016/j.resuscitation.2009.09.015.

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