PFC liquid assisted ventilation has been shown to improve gas exchange and pulmonary mechanics in neonatal and adult animals with respiratory distress. Although PFCs are bioinert, nontoxic, and non-biotransformable, some PFC enters the blood following intratracheal administration. To evaluate the effect of pre-existing lung dysfunction on the uptake of PFC into the blood, 23 young rabbits with normal (N) or saline lavage injured lungs (SI) were studied during gas ventilation after instillation of PFC liquid (APF 140M, Air Products and Chem Inc. or Liquivent®, Alliance Pharm. Corp.) equal to the measured gas functional residual capacity. The animals were anesthetized, paralyzed, supported by time-cycled, pressure-limited ventilation; SI was produced by sequential 10 ml/kg lavages of warmed saline to produce a 50% decrease in dynamic compliance and PaO2 ≤ 100 mmHg with an F1O2 = 1.0. The animals were studied in 4 groups [GR1: N w/ APF 140M, n=5; GR 2: SI w/ APF 140M, n=6; GR 3: N w/ Liquivent®, n=6; GR 4: SI w/ Liquivent®, n=6] for 4 hours and managed to maintain physiological blood chemistry and constant minute ventilation; sequential arterial blood samples were taken for blood chemistry and PFC analyses prior to PFC instillation and at 15 min intervals. Arterial blood PFC content(CaPFC:μ gm/gm) was determined by headspace analysis with electron capture detector gas chromatography; saturation of PFC in the expired gas(PFC-Sat%) was analyzed by thermal conductivity. Results over 4 hours are presented (mean ± SE). These data demonstrate that independent of the PFC used, CaPFC is greater (p<.01) in the N (Grs 1 and 3) vs SI (Grs 2 and 4) lung. These results may be related to stratification of PFC liquid and gas in the lung, injury-induced diffusional barriers and intrapulmonary shunting. In addition, CaPFC and expired PFC-Sat% is greater (p<.01) after APF 140M as compared to Liquivent® instillation, independent of lung condition. The differences in PFC-Sat% may reflect a more homogeneous distribution pattern with APF 140M whereas the relatively greater CaPFC of APF 140M may be due to its relatively higher PFC-Sat% and higher vapor pressure providing a greater driving force across the lung. This study may provide insight regarding the effect of differences in lung condition, physicochemical properties of the PFC liquids, and physiological responses following PFC liquid instillation on PFC blood uptake. (Supp: AlliancePharm Corp, Air Products and Chem Inc, R29HD26341) Table

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