RELATIONSHIP BETWEEN THE GAS-COMPOSITION OF THE MIDDLE-EAR AND THE VENOUS-BLOOD AT STEADY-STATE

Concomitant continuous measurements of the steady-state gas compositio n of the middle ear and of the venous blood were recorded by mass spec trometry in four guinea pigs, The following mean values were obtained for the partial pressures of middle ear gases; nitrogen + argon, 606.4 mm Hg; oxygen, 46.2 mm Hg; and carbon dioxide, 60.2 mm Hg, The corres ponding values for the venous blood were as follows: Nitrogen + argon, 563.4 mm Hg; oxygen, 38.0 mm Hg; and carbon dioxide, 61.4 mm Hg. The similarity of the steady-state gas composition of the middle ear to th at of the venous blood suggests that the partial pressures of the gase s in the middle ear are controlled by interchange with gases present i n the blood.