Gas transport and pulmonary perfusion during high-frequency ventilation in humans.

Regional pulmonary 133Xe clearances, regional 133Xe washins, regional distribution of pulmonary blood flow, and pulmonary gas exchange were determined during high-frequency small-volume ventilation (HFV, oscillation frequencies 12 or 18 Hz, stroke volumes 1.2-0.8 ml/kg) in six healthy anesthetized-paralyzed volunteers lying supine. Adequate pulmonary gas exchange was maintained by HFV; the efficiency of oxygenation during HFV did not differ significantly from that during conventional mechanical ventilation at similar mean lung volumes. During HFV regional pulmonary clearances and washins of tracer gas were different among regions. Apical nondependent lung regions cleared faster and had greater regional longitudinal gas conductances than did basal nondependent or dependent regions. The vertical gradient for pulmonary perfusion was preserved during HFV. Apparently the rate of interregional gas mixing is small during HFV at 12 and 18 Hz in anesthetized-paralyzed humans.