Effects of pulmonary edema on regional blood volume and red blood cell transit time. Comparison of high pressure and oleic acid-induced edema.

Abstract

The present study was designed to determine the effects of pulmonary vascular pressure, vascular injury, and pulmonary edema on regional blood volume (Vr) and regional red blood cell (RBC) transit time (Tr) in the lung. The experiments were carried out in 15 dogs. Six served as controls, six had oleic acid-induced pulmonary edema (OAPE), and three had high pressure pulmonary edema (HPPE). Regional blood flow (Qr) was measured with 99mTc macroaggregates, Vr with 51Cr homologous RBC, and regional transit time was calculated (Vr/Qr). The dogs were killed, and the lungs removed and sampled completely. Regional extravascular lung water (EVLW) was measured in grams per gram of dry lung and ranged from 3.7 +/- 1.1 in the control group to 6.0 +/- 1.3 in OAPE and 5.6 +/- 0.6 in HPPE. The data show that in normal lungs, increased Qr was associated with a recruitment of blood volume. In OAPE, data show that regional blood volume was decreased and that vascular injury and edema formation interfered with a further increase in Vr as Qr increased. In HPPE, Vr has already fully distended and it changed little with increased blood flow. We conclude that oleic acid-induced pulmonary injury and edema interfere with vascular recruitment and shorten regional RBC transit times. HPPE, on the other hand, is associated with normal regional RBC transit times because the vessels are fully recruited.