Comparative evaluation of the usability of 2 different methods to perform mild hypothermia in patients with out-of-hospital cardiac arrest

Background: Several studies have shown that mild hypothermia (32-34 degrees C) markedly mitigates brain damage after cardiac arrest (CA). This study aimed to compare the efficacy of the non-invasive cooling device Hilotherm (R) Clinic (Hilotherm (R) GmbH, Germany) with conventional cooling to induce and maintain mild hypothermia in patients after out-of-hospital CA. Methods: 50 adult patients with an indication for controlled mild hypothermia were prospectively assigned to conventional cooling (n=20) or cooling with the Hilotherm system (n=30). Patients receiving a cooling therapy by Hilotherm were treated either with 0.35 m(2) (n=20) or with 0.7 m(2) (n=10) surface area of cooling sleeves. Results: The speed of cooling was significantly higher in both Hilotherm groups compared to conventional cooling (Hilotherm 0.7 m(2): 0.91 +/- 0.08 degrees C/h, Hilotherm 0.35 m(2): 0.47 +/- 0.04 degrees C/h, and conventional: 0.3 +/- 0.04 degrees C/h, p <= 0.003). Temperature deviation from the target temperature of 33 degrees C was significantly higher in the conventional group compared to both Hilotherm groups. During induction of mild hypothermia a significant reduction of the mean arterial blood pressure and the heart rate was observed without significant differences between the groups. However, the speed of cooling (range 0.3-0.91 degrees C/h) did not correlate to the decrease of blood pressure and heart rate. Norepinephrine dosing during induction of mild hypothermia and re-warming (1st-2nd day) was significantly increased compared to the 3rd day after admission in all groups. Dobutamine dosing and 30 days in-hospital mortality did not differ significantly between the groups. Conclusions: Rapid and reliable mild hypothermia can be better achieved by the non-invasive cooling system Hilotherm compared to conventional cooling with ice packs and cold infusion. (C) 2010 Elsevier Ireland Ltd. All rights reserved.