Evaluation of Lung Volumes and Intrapulmonary Gas Mixing in Diseased and Normal Children

¹ Medical Student Research Grant of the National Science Foundation, Summer, 1958.
² Medical Student Fellow of the National Foundation, Summer, 1958.

Clinical evaluation of respiratory status in chronic diseases of childhood depends upon: (1) the use of meaningful values which accurately portray pathophysiological changes and which may be determined with relative ease: (2) determination of adequate baseline values on normal subjects to which the finding in disease may be compared; and (3) the use of serial determinations throughout the natural history of the disease.

In this study lung volumes and intrapulmonary gas mixing values determined in the supine position in 50 normal children are compared to those of 21 children with asthma, post-paralytic polio, or cystic fibrosis of the pancreas. Inspiratory capacity, expiratory reserve volume and vital capacity were determined by spirometry. The functional residual capacity was determined by an open circuit nitrogen dilution technique. Gas mixing efficiency as defined by the clearance equivalent was also determined.

On the basis of this study it may be concluded that changes in lung volumes, intervolume ratios, and intrapulmonary gas mixing may be used to evaluate clinical changes in chronic pulmonary diseases of childhood and that serial determinations give added significance to these studies.