Determination of Distribution of Diffusing Capacity in Relation to Blood Flow in the Human Lung

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Abstract

A method for appraising the distribution of diffusing capacity of the lungs (DL) in relationship to pulmonary capillary blood flow ([unk]QC) in normal human subjects was derived from measurements of oxygen diffusing capacity (DLO2) and carbon monoxide diffusing capacity (DLCO) performed during breath holding. This method utilizes the fact that the observed DLO2 is considerably reduced in value if uneven distribution of DL with respect to [unk]QC (uneven DL/[unk]QC) is present. In contrast, DLCO is barely affected by uneven DL/[unk]QC, and from its measured value one can calculate the value DLO2 would have if no uneven DL/[unk]QC were present (true DLO2). Once observed DLO2 and true DLO2 are known, the degree of uneven DL/[unk]QC in the lung can be calculated.

Authors

Richard W. Hyde, Richard Rynes, Gordon G. Power, Jean Nairn