Elsevier

Resuscitation

Volume 76, Issue 3, March 2008, Pages 360-363
Resuscitation

Clinical paper
Prehospital induction of therapeutic hypothermia during CPR: A pilot study

https://doi.org/10.1016/j.resuscitation.2007.08.015Get rights and content

Summary

Aim of the study

We studied induction of therapeutic hypothermia during prehospital resuscitation from cardiac arrest using an infusion of ice-cold Ringer's solution in five adult patients.

Material and methods

Paramedics infused +4 °C Ringer's solution into the antecubital vein of the patients with a maximum rate of 33 ml/min to a target temperature of 33.0 °C.

Results

The mean infused volume of cold fluid was 14.0 ml/kg, which resulted in a mean decrease of 2.5 °C in nasopharyngeal temperature. The decrease in temperature continued after the cessation of infusion in two patients, causing suboptimal temperatures below 32 °C.

Conclusion

We conclude that the infusion of small volumes of ice-cold Ringer's solution during resuscitation results in an effective decrease in nasopharyngeal temperature. Caution should be taken to avoid temperatures below the range of mild therapeutic hypothermia.

Introduction

Mild therapeutic hypothermia improves survival and neurological outcome in comatose survivors of out-of-hospital cardiac arrest.1, 2 Current resuscitation guidelines recommend that therapeutic hypothermia should be induced as soon as possible,3 and there is evidence that delays in the cooling process negates the beneficial effects of this treatment.4, 5 In experimental cardiac arrest studies, intra-arrest cooling significantly improved resuscitation outcomes.6, 7 Infusion of ice-cold intravenous fluids for induction of therapeutic hypothermia has been found to be feasible and safe after return of spontaneous circulation (ROSC) in humans,8, 9, 10, 11 and one experimental study has shown this method to also be effective during ongoing cardiopulmonary resuscitation (CPR).12 We report our initial experience in the use of intravenous infusion of ice-cold Ringer's solution during ongoing CPR in prehospital patients treated by paramedics. The aim was to evaluate the feasibility of this approach and to study the cooling effects of this treatment during cardiac arrest.

Section snippets

Material and methods

We enrolled five consecutive patients treated by the paramedic-staffed Tampere Emergency Medical Service (EMS) system. This is a two-tiered EMS system with basic emergency medical technicians in the first tier, backed up by paramedics as a second tier. Patients, aged ≥18 years with cardiac arrest not due to trauma or intoxication, were included regardless of the initial cardiac rhythm. Exclusion criteria were pregnancy, return of spontaneous circulation within 5 min from the onset of

Results

The data of the study patients are shown in Table 1. There were four male and one female patient. Their mean age was 68 years and mean weight was 77 kg. All patients were resuscitated indoors. The initial cardiac rhythms were pulseless electrical activity in three patients, ventricular fibrillation in one and asystole in one patient. The mean delay from the onset of resuscitative efforts to infusion of cold fluids was 10 min.

During CPR, the mean volume of infused cold solution was 892 ml during a

Discussion

In this pilot study, induction of therapeutic hypothermia by paramedics using cold fluids via a peripheral vessel was found to be feasible during CPR. We found that the infusion of moderate amounts of cold (+4 °C) Ringer's acetate during cardiopulmonary resuscitation resulted in a fall in nasopharyngeal temperature during ongoing CPR. The volumes needed were smaller than in our previous study.9 It has been estimated that an infusion of 30 ml/kg of +4 °C saline decreases core temperature by 1.5 °C.3

Conclusions

We found that induction of therapeutic hypothermia using infusion of cold Ringer's solution by paramedics during cardiopulmonary resuscitation was feasible. This method warrants caution, however, as temperature is prone to decrease rapidly with small volumes of cold fluid and the decrease seems to continue even after the cessation of infusion. To which degree nasopharyngeal temperature reflects brain temperature in this context has to be further investigated.

Conflict of interest

None of the authors have conflicts of interest to declare.

Acknowledgement

We wish to thank the paramedics of the Tampere EMS system for their co-operation during this and future studies.

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  • Cited by (53)

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    A Spanish translated version of the summary of this article appears as Appendix in the final online version at 10.1016/j.resuscitation.2007.08.015.

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