The Determination of Alveolar Carbon Dioxid Tension by a Simple Method

In acidosis the tension, that is to say, the effective concentration of carbon dioxid in the alveolar air, is diminished.1By the determination of this tension the diagnosis of acidosis may be made, the degree of severity estimated, and the results of treatment followed. The determination may be carried out in a few minutes' time and with no especial discomfort to the patient. Two procedures are involved: the collection of the alveolar air, and the analysis of the sample. COLLECTION OF ALVEOLAR AIR The method of collection is essentially that of Plesch,2as modified by Higgins.3A rubber bag of approximately 1,500 c.c. capacity4is connected by means of a short rubber tube to a glass mouthpiece.5About 600 c.c. of air are blown into the bag with an atomizer bulb, and the rubber tube clamped off by a pinchcock. The subject should be at