Abstract 353: New Technique of Gas Adiabatic Expansion for Brain and General Hypothermia in Pig
Objective: The purpose of this work was to confirm on a pig model the previous work performed on a rabbit model (ReSS 2012) to demonstrate induction of both brain and general hypothermia on a beating heart.
Material and method: 8 Landrace pigs 39.4 ± 3.9 kg (mean ± SD) were studied under general anesthesia according to the WICCM protocol. Temperatures were measured by thermocouples every minute, after each injection: close to the injector inserted up to the nasopharynx without contact to the posterior wall, in the retrograde jugular vein, in the tympanic area, in the esophagus and in the rectum. After stabilization of temperatures, CO2 regulated at 580 psi (40 bar) was delivered for periods of 10 min. Valid data were obtained from 14 injections. We compared the drops in temperatures recorded until stabilization. In these pigs 2 ± 1.5 injections of CO2 were delivered.
Results: The initial 90% drop in temperature was detected after 4.7 ± 1.4 min for tympanic and 9.4 ± 4 min p=0.02 for the core temperature. Temperatures recorded from the tympanic/jugular probes were identical p=1. Return to stable temperature was observed in 10-15 mn. Esophagus drop in temperature was 23 ± 10 °C n=6. The drop in temperature was significantly higher in the tympanic area 0.69 ± 0.4 °C than in the core temperature 0.36 ± 0.15 p = 0.02. The amount of extracted calories was 14.9 ± 6.7 kilocalories.
Discussion: Core temperature drop was similar to that reported in pigs after nasopharynx PFC evaporation (Yu et al Crit Care Med. 2010). In our experiments the lowest temperature (-30°C) was recorded, as expected, at the exit point for the gas. Significant decrease in temperature of 26°C in the esophagus was always observed.
Conclusion: This study confirms that CO2 expansion in the nasopharynx is effective for brain and body hypothermia in a pig model. This new technique which is simple, inexpensive and easy to use opens new vistas for the treatment of OHCA which, mixed with oxygen, can be started intra-arrest before CPR.
- © 2013 by American Heart Association, Inc.