Clinical paperCold saline infusion and ice packs alone are effective in inducing and maintaining therapeutic hypothermia after cardiac arrest☆
Introduction
The outcome among patients admitted to hospital after out-of-hospital cardiac arrest is still relatively poor. However, induced mild hypothermia can improve survival and the neurological outcome.1, 2 Hypothermia treatment is recommended for witnessed cardiac arrest with initial ventricular tachycardia/ventricular fibrillation (VT/VF) and should be considered in other initial ECG rhythms according to current cardiopulmonary resuscitation (CPR) guidelines.3, 4 The effect of hypothermia on the neurological outcome would seem to be most beneficial when the treatment is initiated as early as possible after restoration of spontaneous circulation (ROSC) and maintained for 12–24 h.5, 6, 7 Despite its recommendation in current CPR guidelines3, 4 therapeutic hypothermia after cardiac arrest is not used in clinical practice in all hospitals caring for these patients, for reasons based on scientific, technical, logistical and economic issues.8, 9, 10, 11
The ideal method for inducing and maintaining therapeutic hypothermia is not known. Different cooling methods and devices are described for administration of this therapy, such as surface cooling, 1, 2, 12 cooling with endovascular catheters,13, 14, 15, 16 use of cooling caps/helmets,17 and cool intravascular fluid.13, 18 Among these methods, surface cooling is generally considered the least expensive and is the most widely used. However, these methods are often combined with induction of hypothermia by cold infusion.19 Cold infusion alone is effective for such induction but is inadequate for maintaining hypothermia.6 In a study by Bernard et al.,18 the use of cold, 4 °C, intravenous crystalloid infusion was combined with ice packs applied in the groins, axillae and along the neck. In that study induction to the target temperature of hypothermia treatment was achieved, but maintenance of hypothermia and the length of the rewarming phase were not reported.
The aim of the present study was to further evaluate the temperature control with cold, 4 °C intravenous crystalloid infusion combined with ice packs for hypothermia treatment not only during induction but also during maintenance and rewarming.
We hypothesised that with this method a target temperature of between 32 and 34 °C can be achieved and maintained during treatment, and that rewarming can be controlled.
Section snippets
Methods
This was a prospective observational study comprising patients treated with hypothermia at the Intensive Care Unit (ICU) of Uppsala University Hospital, Uppsala, Sweden, after cardiac arrest between December 2004 and June 2007. The study was reviewed and approved by the local human ethics committee in Uppsala. Consent to participation was obtained from a legal next of kin, and later from survivors when they were considered competent. The patients were eligible for inclusion if they were still
Results
During the 30-month period of the study, 38 of the 45 patients treated with hypothermia after cardiac arrest were included. In five of the seven patients not included in the study the temperature protocol was not filled in by the staff. In one patient, hypothermia treatment was begun >6 h after cardiac arrest. One patient with cardiac arrest due to trauma was not included in the study, but the patient received hypothermia treatment. Patients were cooled after both out-of-hospital and in-hospital
Discussion
In this study of cardiac arrest patients, cold saline infusion combined with ice packs was found to be effective in inducing and maintaining therapeutic hypothermia and also in controlling rewarming. However, close monitoring of the body temperature was required to achieve this.
All patients in the study (n = 38) reached the target temperature of 32–34 °C, on average 4.4 h from cardiac arrest and 3.4 h after initiation of hypothermia treatment, results which are comparable to those with external and
Conclusion
Use of cold intravenous saline infusion (4 °C) together with ice packs placed in the groins, axillae and along the neck is an effective method for inducing and maintaining therapeutic hypothermia after cardiac arrest with good temperature control even during the rewarming phase. The method is feasible in clinical practice at low cost and should be considered as an alternative to other methods of planned hypothermia treatment.
Conflict of interest
There is no conflict of interest.
Acknowledgements
We thank the staff at the General ICU, Uppsala University Hospital, for their assistance in data collection, Lars Berglund at the Uppsala Clinical Research Center for statistical advice, and the Department of Surgical Sciences, Anaesthesiology & Intensive Care, Uppsala University for institutional grants.
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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.2009.09.012.