実験的減圧症に関する研究 : とくに心音図を中心として

Abstract

Phonocardiograms and electrocardiograms of rabbits in an experimental high barometric pressure tank were studied in normal, compressed and decompressed states. Provoking conditions of the decompression sickness, dissection findings of the lethal cases, and the recovery of the animal from ckokes were also observed. Furthermore, heartsounds of the animal were observed under normal pressure, inhaling air rich in oxygen. The results obtained are as follows. 1) Under high pressure, the amplitude of the first and the second heartsounds decreased. But after the decompression they both increased, and the increase of the amplitude of the first was especially remarkable. 2) The heart rates were reduced after the compression and showed an increasing tendency after the decompression. 3) Under high pressure, the electrocardiogram changed only a little. In lethal cases by serious decompression sickness auriculo ventricular block and auricular fibrillation were observed; while in recovered cases from chokes, negative T was observed. 4) It seems that the lowest limit of the onset conditions determined by K. Ueda is higher than that deduced by the author's results. 5) Dissection findings showed that there were bubbles in all blood vessels. 6) Recompressing to the previous high pressure, the choked rabbit lay in ventral position some 20 minutes after the commencement, and after one hour it stood up and began to walk. 7) Inhaling air added with aboundant oxygen under normal pressure, the amplitude of the animal's first and second heartsounds decreased. Restoring to the inhalation of the normal air, the amplitude showed a tendency of increase. It seems that the decrease of the amplitude of the heartsounds under high pressure is due to the increase of the partial pressure of oxygen in the air.