Clinical paperCold infusions alone are effective for induction of therapeutic hypothermia but do not keep patients cool after cardiac arrest☆
Introduction
Mild hypothermia improves survival and neurological outcome after out-of-hospital cardiac arrest.1, 2, 3 According to the results of two large randomised controlled trials the European Resuscitation Council Guidelines 2005 recommend treating comatose survivors of out-of-hospital cardiac arrest due to a shockable rhythm with mild hypothermia for 12–24 h.4 The ideal method for induction and maintenance of therapeutic hypothermia is not known. As experimental results suggest that the effect of hypothermia on neurological outcome might be most beneficial when applied as early as possible after return of spontaneous circulation5, 6 recent research focused on methods for fast induction of hypothermia.7, 8, 9, 10, 11, 12, 13 So far, five feasibility trials have investigated the efficacy and safety of large volume infusions of cold infusions in more than 200 adult cardiac arrest survivors (9–13). Those studies showed that hypothermia could be induced very effectively with cooling rates up to −4.0 °C/h and no clinically relevant adverse effects of the infusions, especially no pulmonary oedema, were observed. Although the target temperature (32–34 °C) could be reached in most patients, hypothermia was then maintained by additional more resource demanding cooling techniques. To our knowledge no study has investigated, if hypothermia can be induced and also maintained by repetitive infusions of cold crystalloid fluids and complete muscle relaxation with deep sedation.
Section snippets
Methods
This was a prospective, observational case series of a convenience sample of patients after cardiac arrest admitted to an emergency department of a tertiary care hospital between October 2005 and February 2006. The study procedures were approved by the responsible committee on human experimentation. According to our study protocol there was no need for patient's consent to be included in our study but patients or their relatives received detailed information about the trial.
Inclusion and
Results
The demographics and cardiac arrest data of the 20 patients studied are presented in Table 2. Bladder temperature on admission was 35.2 (±1.1) °C. A total amount of 2465 (±536) ml of cold infusions was given commencing 93 (±62) min after return of spontaneous circulation and 27 (16; 87) min after admission. Cold infusions were started at a mean patient temperature of 35.4 (±0.9) °C which dropped to 34.4 (±1.1) °C after 30 min (p < 0.001) and to 34.2 (±1.0) °C after 60 min (p < 0.001), respectively (Figure 2
Discussion
In most patients who achieve return of spontaneous circulation after cardiac arrest hypothermia can be successfully induced by cold infusions. Although large amounts of fluid were administered within 30 min, no serious side effects occurred. Once the target temperature was reached few patients remained within the temperature range of 32–34 °C but the majority rewarmed within several hours and required additional endovascular cooling. No patient required active rewarming during the induction or
Conclusion
In the majority of patients after cardiac arrest, therapeutic hypothermia can be induced by rapid infusion of cold fluids. However, most patients rewarm after 3–4 h and require additional cooling. As most therapeutic and diagnostic interventions can be performed within this period (e.g. coronary angiography or computed tomography) the induction of hypothermia with cold infusions will allow a rapid induction of hypothermia in this first critical phase after the arrest while more resource
Conflict of interest statement
There are no conflicts of interest.
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2016, Anaesthesia Critical Care and Pain MedicineCitation Excerpt :In the end, in a prehospital situation, this is not the only method of induction and is not sufficient in itself for the maintenance of hypothermia; internal and external cooling methods should be associated appropriately [2,4,5,11]. The targeted population and temperature, the ideal moment in the initiation of a thermic control, advantageously ensured by the application of multimodal protocols, should be better clarified and be the object of further studies [9,22–28]. The studies for inducing hypothermia per cardiopulmonary resuscitation should only be considered after the careful management of all the available techniques.
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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.2006.08.023.