J.Jpn. Surg. Soc.. 57(7): 1129-1163, 1956

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STUDIES ON THE GENERAL HYPOTHERMIA AND THE INDUCTION OF THE VENTRICULAR FIBRILLATION

The general hypothermia was applied to dogs through the immersion method, cooling the rectal temperatur to 17.8°C on average. In those cases the increase of the viscosity of blood due to the hemoconcentralion and the cardiac arrest were noticed in 50% of the dogs, of which the ventricular fibrillation and the cardiac standstill were 30% and 20% respectively, remaining 20% of them survived.
However, after being placed on the blood letting and the transfusion of DEXTRAN and GLYCOALGIN to dilute the concentrated blood on hypothermia, the period of the refrigerating time was apparently shortened which was on average no longer than 72% of that of the no-diluted cases. Cardiac standstill was noticed only in 15% of the cases and the survival was 57.1%.
Through the experiment of the electric stimulation of the sinoauricular node by means of the pace-maker stimulator, I tried to find out the lowest threshold of the temperature in hypothermia and obtained the result that dogs could not keep the heart beating under the temperature of 15°C, even when the hemodilution was attempted.
Also the threshold of the electric stimulus to induce the fibrillation on hypothermia was studied, placing the alternating current on the anterior wall of the chest and the base of the right ventricle for the period of two seconds. This study revealed that the lower the temperature, the lower the threshold of current for fibrillation, except for the fact that it is rather high on the stage between 18 and 21 °C.
When dogs were placed on anoxia or hypercapnia, the ventricular fibrillation occurred with minimal stimuli which were impossible to be recorded. On the other hand, if the blocking of the sympathetic nervous system was carried out through the blocking agents or sympathectomy, and further hemodilution was added, the threshold for inducing the fibrillation became so high that it scarcely occurred even on anoxia or hypercapnia.
Of 127 cases of the clinical application of the hypothermia the cardiac arrest was noticed in 8 cases-ventricular fibrillation 4 cases and cardiac standstill 4 cases. The 7 of these 8 cases occurred when cardiac occlusion were released and 1 case was considered to be due to the vago-vagal reflex.
(author's abstract)

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