Distribution of ventilation and blood flow during exercise in emphysema.

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Abstract
The functional residual capacity, ventilation distribution, pulmonary blood flow distribution, ventilation perfusion ratios, and arterial blood gases were measured at rest and during treadmill exercise in 15 emphysematous patients with mild hypoxemia (group A: average Sa = 91%), and 4 with more severe hypoxemia and with cor pulmonale (group B: average Sa -86%). During exercise Sa fell to 77% in group B whereas it increased slightly in group A to 92%. Changes in pulmonary blood flow distribution appear to account for the marked fall in Sa during exercise in patients with pulmonary emphysema and cor pulmonale. In these patients, in the resting state, fractional blood perfusion to the "slow space" is higher than in patients of group A and it appears to increase further during exercise, whereas this fraction decreases significantly in patients of group A. A small increase in functional residual capacity was observed during exercise in most emphysematous patients.