Lung water accumulation with acute hemodilution in dogs

Extravascular lung water content was determined in vivo, gravimetrically, and histologically in severely hemodiluted (Ringer's lactate), supine, spontaneously breathing, halothane-anesthetized dogs. One group of dogs was studied immediately after undergoing hemodilution to a hematocrit value of less than 10 per cent; a second group was studied after hemodilution and 1 hour of circulatory maintenance with Ringer's lactate; and a third group was evaluated after hemodilution, maintenance for one hour with Ringer's lactate, and reconstitution of oncotic pressure with 75 Gm human salt-poor albumin. Lung water content was increased significantly from a normal of 3.88 Gm water per gram of dry weight to 4.70 Gm per gram of dry weight by hemodilution; it was increased further to 5.71 tgm per gram of dry weight during 1 hour of maintenance with Ringer's lactate. Reconstitution of oncotic pressure decreased the water content significantly to 4.96 and decreased the units demonstrating perivascular-peribronchial cuffing from 81 to 23 per cent. Double indication-dilution measurement of PEVW failed to reliably reflect changes in lung water. Arterial PO2 with the animals breathing 100 per cent oxygen was unchanged in all of the groups. We made the following conclusions: (1) lung water accumulation occurs during severe hemodilution and serum protein depletion; (2) this may be partially reversed by restoration of oncotic pressure; (3) double indicator-dilution PEVW measurements do not reliably reflect changes in extravascular lung water of less than 47 per cent; and (4) interstitial edema of this magnitude does not interfere with blood-gas exchange.