In the twelfth paper of this series, Wolff and Lennox1 showed by experiments on animals that an increased concentration of carbon dioxide increases the volume of blood passing through the brain by raising the systemic blood pressure and by dilating the cerebral arteries. Venous blood becomes more arterial-like (richer in oxygen and poorer in carbon dioxide). They expressed the belief that the most effective measure for increasing the supply of blood, and hence of oxygen, to the tissues of the brain is the inhalation of a mixture of 90 per cent oxygen and 10 per cent carbon dioxide. The latter increases the diameter of arteries and, by inducing a condition of acidosis, increases the dissociation of oxygen from hemoglobin and makes more oxygen available for the tissues. It also stimulates respiration and increases the blood pressure.
It is, of course, impracticable to duplicate such experiments on human beings, but
COBB S, FREMONT-SMITH F. XVI. CHANGES IN THE HUMAN RETINAL CIRCULATION AND IN THE PRESSURE OF THE CEREBROSPINAL FLUID DURING INHALATION OF A MIXTURE OF CARBON DIOXIDE AND OXYGEN. Arch NeurPsych. 1931;26(4):731–736. doi:10.1001/archneurpsyc.1931.02230100047004
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