Oxygen washout studies in the anesthetized dog

Abstract

To evaluate technique for producing hypoxia in patients during radiotherapy, anesthetized dogs were hyperventilated with N₂ for 3 min. End-tidal Po₂ fell rapidly to near zero, but arterial Po₂ fell to 10 mm Hg with mixed venous Po₂ fractionally higher. Mean tissue Po₂ of cortical gray matter fell to 0.7 mm Hg, white matter to 1.7, and subcutaneous tissue to 1.8, but muscle fell only to 7.8 mm Hg. Reasons for failure of oxygen washout are discussed. N₂ inhalation; radiosensitivity; muscle Po₂; brain Po₂; tissue Po₂; polarography; cerebral cortical cell inhibition; arterio-venous Po₂ Submitted on October 25, 1962