INSPIRATORY FLOW AND INTRA-PULMONARY GAS-DISTRIBUTION

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Abstract
The effect of flow of inspired gas on intrapulmonary gas distribution was examined by analysis of regional pulmonary 133Xe clearances and of total pulmonary 133Xe clearance measured at the mouth after equilibration of the lungs with 133Xe. Five awake healthy men (24-40 yr of age) and another 5 healthy, anesthetized-paralyzed men (26-28 yr of age) were studied while they were in the right lateral decubitus position. The awake subjects were studied at 3 inspiratory flows (0.4, 0.7 and 1.0 l/s) and the anesthetized-paralyzed subjects at 4 inspiratory flows (0.2, 0.5, 1.1 and 1.6 l/s). Interregional differences in 133Xe clearances along the vertical axis were significantly less during anesthesia-paralysis and mechanical ventilation than during spontaneous breathing in the awake state. No differences in the regional or total pulmonary 133Xe clearances were detected at these different flows in either of the 2 states, i.e., the difference between the awake and anesthetized-paralyzed states persisted.