THE ARTERIAL-ALVEOLAR INERT GAS (“N2”) DIFFERENCE IN NORMAL AND EMPHYSEMATOUS SUBJECTS, AS INDICATED BY THE ANALYSIS OF URINE*

Open Access
Publisher Website
Google Scholar
Abstract
A method is described which allows one to calculate the partial pressure of inert gas, ("N2"), in arterial blood within [plus or minus] 2 mm Hg. This calculation is based upon an analysis of the inert gas content found in anaerobically collected bladder urine. When this is compared with the mean alveolar inert gas ("N2") pressure, one finds that in healthy subjects the arterial N2 pressure is on the average 3.4 mm Hg higher and in patients with diffuse, obstructive emphysema, 22 mm Hg higher than that found in the mean alveolar gas. Such an arterial-alveolar N2 pressure difference can only be accounted for by variance of the ventilation-perfusion ratio among alveoli of the lung. In normal subjects this variance is small, but must be very large in emphysematous patients.