Comparison of surface cooling and invasive cooling for rapid induction of mild therapeutic hypothermia in pigs--effectiveness of two different devices.

AIM OF THE STUDY The effectiveness and safety of non-invasive surface cooling was compared to invasive endovascular cooling in an animal model. METHODS Eight healthy pigs (29-38 kg) were cooled twice, starting in the first 4 pigs with unique surface cooling pads followed by endovascular cooling. In the second 4 pigs the order was reversed. The goal was to quickly lower pulmonary artery temperature from 38 to 33°C. A paired t-test was used to compare cooling rates (°C/h, mean±standard deviation) between both cooling techniques. RESULTS Mean non-invasive surface cooling rate (11.9±3.8°C/h) significantly exceeded mean invasive cooling rate (3.9±0.7°C/h; p<0.001). The mean difference in cooling rates was 8.0±3.6°C/h. No surface cooling related adverse skin reactions were observed. CONCLUSIONS Surface cooling is a simple method for achieving fast cooling rates. In our animal model, non-invasive cooling was three times faster than rapid endovascular cooling without overshoot.