Alveolar permeability and liquid absorption during partial liquid ventilation of rats with perflubron

We examined the effect of instilled perflubron (LiquiVent) on the transport properties of alveolar epithelium in anesthetized rats. Krebs-Ringer bicar bonate (1 to 4 ml) containing I-125-albumin, [H-3]mannitol and [C-14]-sucro se was instilled into airspaces either alone (n = 29), or with 1 (n = 21) o r 2 (n = 12) mi perflubron and sampled 30 min later. Absorption was deduced from the changes in I-125-albumin activity per unit volume in the airspace instillate, and changes in [3H]mannitol and [C-14]sucrose activity per uni t volume were used to evaluate the passive permeability of the alveolar-air way barrier. The rate of Ringer absorption depended on the volume instilled [0.38 (ml/h)/ml Ringer]. Perflubron (1 or 2 mi) increased Ringer absorptio n by 0.26 (p < 0.001) and 0.19 ml/h (p < 0.05), respectively. However, 2 mi perflubron increased absorption less than did the same additional volume o f Ringer (p < 0.007). The passive permeability of the alveolar-airway barri er increased exponentially with instilled Ringer volume. Sucrose/mannitol s ize selectivity was lost when Ringer volume was > 2 ml and albumin leaked f rom airspaces when it was 4 ml, Instillation of 2 mi perflubron prevented t his increase in permeability, but 1 ml did not. No albumin leaked with perf lubron even when the total volume of liquid in airspaces (Ringer + perflubr on) was > 4 ml. These results suggest that perflubron can be beneficial in pulmonary edema by redistributing the alveolar liquid over a larger surface area, thus accelerating resorption. In addition, larger doses of perflubro n may better preserve epithelial permeability during alveolar flooding.