Perfluorochemical elimination from the lungs: Effect of initial dose

Liquid-assisted ventilation with perfluorochemical (PFC) has been beneficia l in a variety of respiratory diseases in animals and humans. Although PFC evaporation from the lungs is In part dependent on ventilation strategy and positioning, guidelines for initial and replacement dosing are unclear. We hypothesized that PFC evaporative loss over time is dependent on the size of the initial dose. Juvenile rabbits (n = 18) were ventilated using consta nt animal position and ventilator strategy. PFC (perflubron: LiquiVent(TM)) was instilled endotracheally, using four groups with initial doses of 2, 6 , 12, and 17 mL/kg. A previously described thermal detector that measures P FC in expired gas was used to calculate loss rate, residual perflubron in t he lung, and volume loss as a % of initial fill volume. There was a significant dose, time, and dose-time interaction such that eva porative loss was dependent on initial PFC volume and time after fill (P < 0.05). Evaporative loss rate decreased earlier at lower doses. The percenta ge of initial volume lost to evaporation over time was Inversely related to dose and could not be predicted by decreasing % PFC saturations, independe nt of dose. Evaporative loss should be considered to optimize both the application of P FC to the lung and replacement dosing during partial liquid ventilation. Pe diatr Pulmonol, 2000; 30:324-329, (C) 2000 Wiley-Liss. Inc.