LIQUID VENTILATION IN PREMATURE LAMBS - UPTAKE, BIODISTRIBUTION AND ELIMINATION OF PERFLUORODECALIN LIQUID

Perfluorochemical (PFC) liquids are biologically inert and nonbiotrans formable substances that, when used as breathing medium, may be transp orted across the lung epithelium in small quantities, distributed thro ughout the body, and ultimately vapourized through the lungs and trans pired through the skin. To further evaluate the uptake, biodistributio n and elimination of a PFC liquid (perfluorodecalin) in the neonatal p opulation, arterial blood, tissue and expired gas samples were obtaine d from preterm lambs (105-114 days gestation). Two groups of premature lambs were studied: Group I (n=4) lambs were liquid ventilated from b irth for 1 h and killed without exposure to gas ventilation (GV) and G roup II (n=5) lambs were liquid ventilated for 1 h followed by up to 2 h of GV. Samples were analysed by electron-capture gas chromatography and data were expressed in nl of PFC/ml of blood or gas and nl of PFC /gm tissue. During liquid ventilation and subsequent GV, PFC blood lev els significantly increased (P<0.001) from baseline control levels (0. 007+/-0.001 SE nl PFC/ml blood) to a high of 2.95+/-1.03 SE nl PFC/ml blood. Perfluorochemical levels measured in expired gas (Group II) dem onstrated a rapid decrease as a function of time of GV. Tissue levels of PFC indicated that uptake of PFC in Group I was significantly diffe rent (P<0.001) than baseline levels and organ dependent; the highest l evels were in the lungs (221+/-26.2 SE nl PFC/g tissue) and the lowest in the liver (2.24+/-1.6 SE nl PFC/g tissue). Comparison of tissue le vels of PFC between groups indicated a 34.8% mean decrease across orga ns in Group II compared with Group I. These data indicate that PFC upt ake and elimination is organ dependent and that PFC liquids can be eli minated through the lungs upon return to GV. Sustained PFC blood level s may be related to residual PFC in the organs and lung as well as reg ional variation in ventilation-perfusion matching upon return to GV.