Cooling blood with ice slurry

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CPR Innovation: New Concepts, Technologies, and Therapeutics

2769 RAPID INDUCTION OF HYPOTHERMIA USING PHASE-CHANGE ICE SLURRY:
TARGETED COOLING OF THE HEART AND BRAIN DURING CARDIAC ARREST

Lance B Becker, Univ of Chicago, Chicago, IL; Kenneth E Kasza, Argonne National Lab, Argonne, IL; David Jayakar, Ursula Williams, Philip Padrid, Univ of Chicago, Chicago, IL; Ahamed H Idris, Univ of Florida, Gainesville, FL; Terry L Vanden Hoek, Univ of Chicago, Chicago, IL

Objectives: Rapid induction of hypothermia may be protective during cardiac arrest but has been difficult to achieve. We hypothesized that phase-change ice-slurries would allow for targeted cooling of the brain and heart during cardiac arrest if the slurry could be delivered into the pulmonary spaces and IV during ongoing CPR.
Methods: We first developed a prototype phase-change saline-based ice-slurry that had 30% ice loading, particle size < 0.1mm, good flowability, and stability. This slurry was tested to determine cool down rates in a standard 35 kg swine arrest (non-survival) model after instrumentation for temperature measurements in the heart, right and left brain, esophagus, and rectum. After cardiac arrest was confirmed, ice-slurry was injected into the pulmonary spaces via endotracheal tube, CPR was initiated, and temperatures recorded over 30 - 40 minutes. In an additional experiment, ice-slurry was also administered via IV.
Results: Temperature cool down graphs reveal that rectal temperature decreased at a mean rate of 0.03° C/min (averaged over 30 - 40 min, n=3). By contrast with only pulmonary ice-slurry, cooling of the heart averaged 0.35° C/min (n=2) and brain averaged 0.16° C/min (n=4) over 30 min. When pulmonary cooling and IV slurry were used simultaneously, heart cooling was faster (0.53° C/min, n=1) as was brain (0.29° C/min, n=2). Pooled data reveals significantly greater decreases in heart and brain temperature than in rectal temperature, p<0.005. During the best 10 minute cooling interval, the brain cooled by 5.2° C in 10 min.
Conclusions: We produced significant heart and brain cooling using techniques that paramedics could employ during CPR. These data are novel as no prior studies exist which use internal phase-change slurries for cooling and no prior study has used pulmonary cooling to attempt targeted cooling of the brain and heart during CPR. The cooling rates we obtained were 10 - 20 times greater than any other method available to paramedics in the out-of-hospital setting and could be easily doubled with improved administration devices in the near future.