The Nature of Zone 4 in Regional Distribution of Pulmonary Blood Flow
The first measurements of the regional distribution of pulmonary blood flow in man were made using O2-labelled carbon dioxide.1 The results in 16 normal upright subjects are shown in Fig.1. The clearance rates were measured during 10–15 seconds breath-holding following an inspiration of one liter of radioactive carbon dioxide from functional residual capacity. If we take the clearance rate of O2-labelled carbon dioxide as a measure of blood flow per unit lung volume,2 Fig.l shows that blood flow increased more or less steadily from the top to the bottom of the upright lung, with very low values at the apex. This general pattern was confirmed by early results with Xenon-133.3,4 A discrepancy, however, was found between these results and those obtained by West et al5 on an isolated dog lung preparation.
KeywordsPulmonary Hypertension Lung Volume Regional Distribution Residual Volume Pulmonary Blood Flow
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- 2.J.B. West(Ed), Regional differences in the lung. Academic Press, New York, San Francisco, London, 1977.Google Scholar
- 12.J. Milic-Emili, and F. Ruf, Effect of expiratory flow rate on closing capacity. In: Distribution of Pulmonary Gas Exchange, INSERM, 22–24, Sept. 1975, Vol. 51, pp.395–396.Google Scholar