Continuous Distributions of Ventilation and Gas Conductance to Perfusion in the Lungs
Overall gas transfer in the lung under a steady state is commonly considered to be limited mainly by uneven distribution of ventilation-perfusion ratios (V̇A/Q̇) and by diffusion impairment (Wagner, 1977). Although remarkable methods allowing one to know the distribution of V̇A/Q̇ in the lung have recently been developed (Yokoyama and Farhi, 1967; Wagner et al., 1974; Evans and Wagner, 1977), no reliable tool has been introduced for directly solving the issue of whether diffusion impairment across the blood-gas barrier contributes significantly to determining the efficiency of pulmonary gas exchange. In 1961, Piiper theoretically analyzed the importance of V̇A/Q̇ and diffusion impairment in terms of “V̇A/Q̇-D/Q̇ field”, but rigorous method to realize his theory has not been accomplished. The present study was, therefore, undertaken to develop a new method for detection of distribution of V̇A/Q̇ and diffusing capacity in the lung using nine gases as indicator gases. Applying the present procedure to patients with interstitial lung disease, the importance of V̇A/Q̇ inequality and of diffusion impairment will be discussed.
KeywordsInterstitial Lung Disease Interstitial Pneumonia Ridge Regression Lung Unit Alveolar Dead Space
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