A method for dealing with data concerning uneven ventilation of the lung and its effects on blood gas transfer

¹ Department of Medicine, Columbia University, College of Physicians and Surgeons, and Cardio-Pulmonary Laboratory, (Columbia University Division), Bellevue Hospital, New York City

This is a consideration of the relationships between the uneven ventilation of the lung and the arterial oxygen saturation and CO₂ tension. In the simplest case, the lung is considered to contain only two differently ventilated and perfused components. Graphic methods are developed for dealing with situations of this type and illustrated by application to the data obtained in a normal subject. Some of the methods outlined here can be applied in situations where the lung is composed of three or more differently ventilated and perfused components. In the normal subject considered here, the uneven ventilation of the lung is compatible with A-a gradients of 6 and 0.8 mm for O₂ and CO₂, respectively.