Pressure Volume Curves of Lamb Lungs and the Lecithin-Sphingomyelin Ratios of Lung Fluid

Abstract

Pressure-volume curves were made of lungs from non-distressed, from asphyxiated and from distressed lambs. The curves of the non-distressed animals differed from the curves of the asphyxiated and of the distressed group. Eleven stability indices were calculated and the summation of these in situ surfactant characteristics was used for individual respiratory distress syndrome diagnosis. Low values (< 2) of lecithin/sphingomyelin (L/S) ratios in lung fluid were found before the 130th day of gestation, but a steep increase of the L/S ratio was present after that period. Postnatal RDS was found in low L/S ratio cases, whereas normal lung stability was noticed in animals with L/S ratios > 2. It is concluded that the prenatal L/S ratio in lung fluid of lambs is of predicting value in RDS experiments and fits well with lung stability characteristics.

Indication of Increase of the Lecithin/Sphingomyelin (L/S) Ratio in Lung Fluid of Lambs Maternally Treated with Metabolite VIII of Bisolvon®

“…Crosses shown in figure la represent the L/S ratios of six lambs from a previous study (9). No differences are noticed between these values and the L/S ratios from the present study.…”

“…Volumes of 5 cm3 were used for the determination of the L/S ratio according to Gluck and Kulovich (12). The technics of phospholipid extraction and measurements have been reported previously (9). Briefly, lipids were extracted with chloroform methanol (2:1 v/v), the chloroform layer was dried under nitrogen and cold acetone was added to precipitate surface-active lecithin.…”

Pulmonary and Circulatory Function in Preterm Lambs Treated with Hydrocortisone <i>in utero</i>

“…Cardiovascular and pulmonary function data in pretemi lambs of less than 130 days gesta tion is remarkably sparse (4,10). The in vitro pulmonary surfactant studies on lamb fetuses by Brumfey et al (1) indicated that the preterm lamb of less than 120 days gestation, because of lack of surfactant, would require assisted venti lation for survival, and that the lungs of animals older than 130 days would behave like mature lungs.…”

“…There have been several studies on the ef fects of glucocorticoids on the biochemical maturation and mechanics of fetal lamb lungs (2,4,9). However, to our knowledge, evalua tion of postnatal pulmonary function and hemodynamic studies on preterm lambs pre treated with steroids have not been reported.…”

“…However, to our knowledge, evalua tion of postnatal pulmonary function and hemodynamic studies on preterm lambs pre treated with steroids have not been reported. The older preterm lamb has been successfully used as a suitable animal model for prolonged 1 Supported by the American Heart Association, Greater Los Angeles Affiliate, grant 529. in vivo observations of pulmonary and circula tory functions (4,10). However, the very young lamb, since it invariably develops respira tory distress and requires ventilatory assistance, has not been widely used for such studies.…”