Lobar blood flow, blod volume and water content in atelectasis

Abstract

In nine intact supine anesthetizedf0 dogs we measured pulmonary blood flow distribution, lobar hemoglobin content, and lobar wet wt/dry wt during left lower lobe collapse. The animals breathed mixture of 88% O 2/12% N 2 and atelectasis was induced by occluding the left lower lobe bronchus. Lobar volume was assessed by measuring lobar N 2 concentrations. Using the radioactive microsphere technique, perfusion distribution was measured at lobar volumes of 50% FRC and 18–25% FRC. Hemoglobin content and wet wt/dry wt were measured at the latter volume. A5t 50% FRC lobar blood flow was unchanged though lobar pressure was negative. At the lower volume lobar blood flow averaged 72% of that at FRC, and lobar hemoglobin content was similar to that of the right lower lobe, indicating that lobar blood volume was unchanged. Wet wt/dry wt was significantly less in collapsed left lower lobes than in control right lower lobes, perhaps indicating that pressure in fluid-exchanging vessels was less than interstitial pressure during atelectasis.