DEVELOPMENTAL DIFFERENCES IN PERFLUBRON UPTAKE INTO THE BLOOD DURING TIDAL LIQUID VENTILATION (TLV) IN THE IMMATURE LAMB. † 1310

Abstract

Tidal liquid ventilation (TLV) with perfluorochemical liquids (PFC) has been shown to provide effective gas exchange in term and preterm lambs with respiratory failure. PFCs have very low surface tensions and have high respiratory gas solubilities. It is these physical characteristics that make PFC an ideal media with which to support gas exchange in the stiff, noncompliant lungs characteristic of Infant Respiratory Distress Syndrome(IRDS). Although PFC is bioinert, nontoxic, and nonbiotransformable, a small quantity does cross into the blood. To determine if there is a developmental difference in PFC uptake in an animal model which resembles the cardiopulmonary development of human neonates currently receiving PFC therapy, 2 groups of premature lambs [Gr 1: 111 ±.23 days; n=6) and Gr 2: 123±.95 days; n=6)] were delivered by caesarean section, anesthetized, paralyzed, tracheotomized, placed on a time-cycled, pressure-limited tidal liquid ventilator, and ventilated with perflubron (Liquivent®: Alliance Pharm. Corp.) for 4 hours. Ventilation was modulated to maintain physiologic blood gases. Blood PFC content was determined by headspace analysis using an electron capture detector gas chromatograph on samples taken in utero, every 15 mins up to 1 hour, and every 30 mins to 4 hrs. These data were compared to that of previously evaluated term lambs (Pediatr Res (37): A1414). Results in μgm/gm (mean ± SE) are presented below:Table These data demonstrate that very minute (all values < 10μgm/gm) but different (*p<.01) quantities cross into the blood of the immature lamb following tidal liquid ventilation. The mean over 4 hrs for Gr 1, Gr 2, and the term lambs were 4.31 ±.29, 6.97±.36, and 7.35 ±.36, respectively, showing comparable levels in term and preterm blood perflubron content. These data suggest that even in the presence of high lung permeability of prematurity, perflubron blood content does not exceed that of a normal, term newborn lamb.(Supp by AlliancePharm Corp,R29HD26341)