Lobar Alveolar Gas Concentration after Pneumonectomy1

We have recently shown that end-expiratory lobar alveolar gas concentrations vary with body position (1). Erect man has higher oxygen and lower carbon dioxide concentrations and a higher R.Q. in the right upper lobe than in the right lower lobe. Supine man has no significant difference between these lobes in R.Q. but the oxygen concentration is lower and the carbon dioxide higher in the upper lobe than in the lower lobe. Changes in lobar gas values in moving from the erect to the recumbent posture may be due to changes in pulmonary ventilation or perfusion. Pulmonary ventilation as a factor has been studied in subjects with pneumoperitoneum (2). With an increased tidal air-functional residual air ratio (3) there is supposedly more uniform ventilation (4, 5) but lobar differences in gas values are similar to those found in normal subjects. Thus a change in pulmonary ventilation with a change of body position does not appear to be the major factor. To examine the role of pulmonary circulation, we have studied subjects following pneumonectomy. With total cardiac output passing through one lung, a more uniform pulmonary perfusion might be expected than in the normal subject.