Studies of Total Pulmonary Capacity and Its Sub-Divisions. Ii. Correlation With Physical and Radiological Measurements

Abstract

In a previous paper (5) we have presented the results of 50 determinations of pulmonary capacity made in an equal number of healthy males.It was demonstrated that the relative capacities (expressed in percentages of the total volume) fluctuated within narrow limits, but that there were wide variations in the absolute figures found for the total volume and its subdivisions. This fact makes rather difficult the recognition of moderate, and perhaps important, deviations in a given case, and also prevents a clear understanding of any alterations in the relative values. Thus a low ratio (Vital capacity/Total volume) X 100 may be caused by either increased residual air, low vital capacity, or a combination of both factors, and the proper interpretation will be obtained only if normal values are available for comparison. To standardize the procedure, it appears to be necessary to find a correlation between the pulmonary capacity and certain bodily characteristics, so that from a knowledge of the latter it may be possible to predict the normal volumes. If we have at our disposal reliable criteria to permit judgment of changes in absolute, as well as in relative pulmonarv capacity a clearer view of the underlying pathological physiology may be obtained. A basis may also be provided for the proper classification and grouping of cases of respiratory inefficiency in which defective alveolar ventilation is an important factor.Although numerous investigations have been made to correlate the vital capacity to body or chest measurements, there have been very few attempts to correlate these characteristics with the total pulmonary capacity or with any one of its subdivisions, other than vital capacity. Lundsgaard and Van Slyke (7) in 1918 found in a few cases a definite correlation between the total capacity, vital capacity, mid capacity and residual air, and the so-called " chest volume," calculated from the external measurement of the three diameters of the chest obtained at the end of full inspiration and expiration under resting conditions. This investigation was later confirmed by Lundsgaard and Schierbeck (6) who found a similar relationship and also conTravelling Fellow of the Rockefeller Foundation. 807

Studies of Total Pulmonary Capacity and Its Subdivisions. V. Normal Values in Female Subjects

“…It was found that the normal values gathered from the literature were insufficient to afford an adequate basis for the detection of pathological alterations, and preliminary studies were consequently made in healthy subjects. The results of measurements made in fifty normal male subjects have been presented in previous papers (11), (12). The data show definite limits of variation for the relative values of some of the subdivisions of the total pulmonary capacity, as well as a definite correlation between the pulmonary capacity and combined physical and radiological measurements of the chest.…”

Studies of Total Pulmonary Capacity and Its Subdivisions. Viii. Observations on Cases of Pulmonary Fibrosis

“…Measurements of the total pulmonary capacity and its subdivisions and their relation to anatomical findings in patients with chronic pulmonary diseases have been presented in previous communications (1) (2). The limits of variation in normal subjects, both male and female, and the method for the prediction of the normal capacity of a given subject have been described (1) (2) (3).…”

Study of the Blood in Chronic Respiratory Diseases, With Special Reference to the Volume of the Blood 1

“…The total pulmonary capacity and its sub-divisions were measured according to the methods used in this clinic (11,12).…”