DISTRIBUTION OF EXOGENOUS SURFACTANT IN RABBITS WITH SEVERE RESPIRATORY-FAILURE - THE EFFECT OF VOLUME

The transient effect of surfactant therapy that is observed in some pa tients might, at least in part, be explained by a nonhomogeneous distr ibution. Therefore, we investigated the distribution of a surfactant p reparation (Alvofact, 45 g/L) that is used clinically. Rabbits with se vere respiratory failure were treated with this surfactant at a dose o f 100 mg/kg body weight, and the distribution of surfactant was determ ined by the use of Ce-141-labeled microspheres that were mixed with th e surfactant. Fifteen min after surfactant administration, the rabbits were killed, and the lungs were removed and divided into 200 pieces. The radioactivity per mg lung tissue was determined in each piece. We found that the endotracheal instillation of this surfactant preparatio n results in a nonhomogeneous distribution. However, a significantly i mproved distribution was obtained when this dose of surfactant (100 mg /kg body weight) was diluted with normal saline to a concentration of 6.25 g/L. The consequence of the administration of this dose was an in tratracheal fluid administration of 16.0 mL/kg body weight. The distri bution was also nonhomogeneous after the administration of a small-vol ume (2.4 mL/kg body weight), low-concentration surfactant preparation (6.25 g/L). We conclude that a surfactant preparation with clinical ap plication is distributed nonhomogeneously in the lungs after endotrach eal administration. The distribution can be significantly improved by increasing the fluid volume in which the surfactant is suspended.