Abstract
When an activity of respiratory center in brain is depressed by high O2 pressure in blood, CO2 pressure in blood increases and respiratory acidosis appears in some patients especially with chronic respiratory diseases. Resipratory acidosis induces disturance of consciousness and the phenomenon is called as CO2 narcosis. The authors reported 2 cases of CO2 narcosis under an inhalation with high concentration of oxygen in O2-tent. The 1st case: 60 years old male was suffered from chronic cor pulmonale during 8 years. He was taken in O2-tent because he had infection of respiratory tract and showed dyspnea. Under the inhalation with air containing 50% of oxygen, he showed sopor 6 hr later. At that time, his PaO2 was 72 mmHg, PaCO2 was 75 mmHg and pH of blood was 7.34. The 2nd case : 70 years old female was suffered from pulmonary emphysema during 6-7 years. She was taken in O2-tent because she had infection of respiratory tract and showed dyspnea. Under the inhalation with air containing 50% of oxygen, she showed somnolence 22 hr later. Her PaO2 was 68 mmHg, PaCO2 was 96 mmHg and pH of blood was 7.33. When both the cases were taken out from the O2-tent and were deeply respired in room air by their voluntary movement, their consciousness, blood gas content and pH improved rapidly. These results suggest a large influence of respiratory air content as a condition of environmental factors on homeostasis.
