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

BackgroundSeveral studies have shown that mild hypothermia (32–34 °C) markedly mitigates brain damage after cardiac arrest (CA). This study aimed to compare the efficacy of the non-invasive cooling device Hilotherm® Clinic (Hilotherm® GmbH, Germany) with conventional cooling to induce and maintain mild hypothermia in patients after out-of-hospital CA.Methods50 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 m2 (n = 20) or with 0.7 m2 (n = 10) surface area of cooling sleeves.ResultsThe speed of cooling was significantly higher in both Hilotherm groups compared to conventional cooling (Hilotherm 0.7 m2: 0.91 ± 0.08 °C/h, Hilotherm 0.35 m2: 0.47 ± 0.04 °C/h, and conventional: 0.3 ± 0.04 °C/h, p ≤ 0.003). Temperature deviation from the target temperature of 33 °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 °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.ConclusionsRapid 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.