Small animals, such as the mouse, rat, and hamster, have been successfully cooled to complete cardiac arrest and then revived by the use of a closed-chamber technique, whereby gradually increasing environmental levels of carbon dioxide and diminishing levels of oxygen occur concomitantly with cold exposure.1-5 Similar results have been attained with dog and man inhaling gas mixtures containing 5%-10% carbon dioxide while undergoing hypothermia.6,7 Hypercapnia and lowered barometric gas pressures have been demonstrated to reduce the oxygen consumption and enhance cooling.8-10 In addition to facilitating the reduction of body temperature, a demonstrated protection by asphyxia or hypercapnia6,11,12 gives evidence to the importance of the respiratory exchange of the hypothermic animal. The purpose of this investigation was to compare the effects of cold alone, asphyxia alone, and the combination of cold and asphyxia upon the respiratory gas exchange during the induction of hypothermia with cardiac arrest.
WILLARD PW, YERKES RC, HORVATH SM. Respiratory Gas ExchangeExperiments in Rats Induced into Cardiac Arrest by Various Procedures. Arch Surg. 1962;84(5):525-532. doi:10.1001/archsurg.1962.01300230041009