気道外酸素投与法の臨床生理学的研究

Clinico-physiological study on extra-tracheal oxygen administration

　呼吸器疾患において，ある程度以上の換気障害，肺内ガス分布障害，拡散障害を来すときは，まずanoxiaを来し，さらにすすめばこれにhypercapniaを伴い，いわゆるasphyxiaの状態におちいる^{1）2）3）4）5）}。

　anoxiaに対しては，種々な対策が行われるが，そのうちでも酸素の吸入は最も有効であり，かつ不可欠の方法である。しかし，asphyxiaの状態にある時には，純酸素，あるいはあまり高濃度の酸素を急速に吸入することは，かえつて呼吸中枢を抑制し時には危険ですらある^6）7）8）。さりとて，肺内ガス分布障害あるいは拡散障害が甚しいときには，わずかの酸素投与によつてはanoxemiaを改善し得ないし，asphyxiaの状態に対しては，さらにarroxemiaの改善に加えてhypercapniaの改善も要求される^9）。

Oxygen inhalation is the most effective and indispensable treatment for anoxemia and asphyxia in cardiopulmonary diseases. However, it is even dangerous sometimes to inhale pure or highly concen-trated oxygen in asphyxia as it inhibits respiratory center. In order to solve the contradiction and difficulty of oxygen inhalation therapy, it is also necessary to investigate the effects and influence of oxygen therapy through some other routes than the respiratory tract on the living body.

The author gave oxygen experimentally to 47 adult dogs through the abdominal cavity, the intest-inal tract which has wide capillary nets, and observed the absorption process of the given oxygen in the abdominal tract, the portal vein, the mixed venous blood and the arterial blood, and gained the following results.

1) Oxygen given into the abdominal cavity or the intestinal tract was sufficiently absorbed into the splanchnic vessels. It met oxygen demand of the liver through the portal vein, and oxygen level of mixed venous as well as arterial blood was increased.

2) The abdominal cavity or the intestinal tract into which oxygen had been given acted like "the second lung." Not only oxygen was sufficiently absorbed, but carbon dioxide was also discharged from veins into the abdominal cavity or the intestinal tract.

3) Carbon dioxide in arterial and venous blood decreased as it found a place to be eliminated extrapulmonary.

4) Due to decrease in CO₂ content in the arterial blood, blood buffer base was lowered resulting in tendency of metabolic acidosis.

5) This method may be considered to be a valuable way to improve anoxemia and hypercapnia, and probably some kind of hepatic disorders, by supplying enough oxygen to the portal vein.