[Experimental study on analysis of the cardiovascular function during carbon monoxide poisoning and resuscitation...

Experimental dogs were intoxicated with 0.5% carbon monoxide until the carboxyhemoglobin level reached 73--81%. Then they were resuscitated with 100% oxygen at normal atmospheric pressure (1ATA), or oxygen at three atmospheric pressure (3ATA). First, the time necessary for half clearance of blood carboxyhemoglobin was measured and compared between above two groups. In the group treated with oxygen at 3ATA (OHP), the time necessary for half clearance was 12 minutes. It was found that when oxygen at 3ATA was administered, carbon monoxide was eliminated 1.4 times faster than group which received oxygen at 1ATA. Secondary, in the present work, we have applied an analytical method for the cardiovascular function by thermodilution method using Swan-Ganz catheter proven under 1ATA to that under hyperbaric conditions. Summarizing the experimental results, it may be said that in CO poisoned dogs even the time when the CO-Hb level exceed 77% (mean-value), generally a slight inhibition of the circulatory system was seen. These changes showed an immediate return to control levels with the initiation of compression of oxygen inhalation. However, following the course for 45 minutes thereafter while almost no change was seen in the aortic pressure and heart rate, both the cardiac index and left ventricular work index showed a decreasing tendency while a prominent rise was seen in the systemic vascular resistance index. Generally in normal dogs under high pressure oxygen, as pointed out by my team, such tendencies as described above are seen. However, in CO poisoned dogs like wise, when the CO-Hb level returns to 10%, the facts that an inhibiting tendency is seen in the cardiovascular system seems to be a point of interest. I am of the opinion that this fact in actual clinical work should be kept in mind when therapy is required in CO poisoning in human subjects. Generally speaking it may be said that when hyperbaric oxygen therapy is indicated, there still remains various problems concerning optimum compression values, the duration of compression and in the compression-decompression pattern for the individual.