APPLICABILITY OF REBREATHING METHOD FOR DETERMINING MIXED VENOUS CO2 IN CASES OF CHRONIC PULMONARY DISEASE

Abstract

The method required the demonstration of the same "plateau" levels of CO2 tension in successive rebreathing expts., when the initial CO2 tensions of the mixtures in the rebreathing bag in the separate expts. varied by several mm., and the demonstration of equilibrium between CO2 tension in the samples of expired air (during rebreathing) and the CO2 tension in the simultaneously drawn arterial blood. The results were: satisfactory in 2 cases of unilateral artificial pneu-mothorax; doubtful in 2 cases of spontaneous pheumo-thorax with positive pleural pressures; and unreliable in a case of advanced bilateral tuberculosis, a case of pulmonary fibrosis with dyspnea, and 2 cases of advanced pulmonary emphysema. By the technique described it can be detd. in a given case whether the method of rebreathing is applicable or not.