Evaluation of a Portable Box-Bag for Field Testing of Pulmonary Diffusion

¹ From the Department of Preventive Medicine and Industrial Health, University of Cincinnati College of Medicine, Cincinnati, Ohio

Values for functional residual gas volume and carbon monoxide uptake were obtained on normal subjects in the laboratory, and on old people living in their own homes, by means of a lightweight portable box-bag. The standard deviation of a single functional residual gas volume measurement (8–10% of mean value) is a little greater than is generally admitted for the closed-circuit technique, but the standard deviation of the carbon monoxide readings (up to 20% of mean value) corresponds closely in accuracy with determinations made by more elaborate laboratory techniques. Both measurements have adequate repeatability for field survey work. The portable box-bag is suitable to indicate a deterioration of respiratory function with both age and emphysema, the carbon monoxide uptake values being more useful than the functional residual gas volume.