Perfluorochemical (PFC) Evaporation from the Lungs: Effect of Initial Dose † 1773

Liquid-assisted ventilation LAV with PFC has been shown to be beneficial in treating a variety of respiratory diseases in animals and humans. While 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 (E_L)profile over time is dependent upon initial dosing. To test this hypothesis, PFC(perflubron:LiquiVent) was instilled endotracheally over 3-5 minutes using three initial volumes (GR I=2ml/kg, GR II=6 ml/kg, GR III =17ml/kg) while repositioning to optimize distribution. Juvenile rabbits (wt =2.2±.7 kg; n=11) were ventilated using a constant position & ventilator strategy: frequency =30br/min, tidal volume= 10.7±.13 ml/kg, V_m=325±4.2 ml/min/kg. A previously described thermal detector device measured PFC content in expired gas and was used to calculate E_L profile[loss rate C'_PFC (ml/kg/hr) and residual PFC in the lung R_PFC (% initial dose)] up to 4 hrs after initial dosing. Data expressed as (Mean±SE). There was a significant dose, time, and dose-time interaction such that E_L profile was dependent on initial PFC volume and time after fill (p<0.05). The total perflubron loss over 4 hrs was 0.96ml/kg(GR I); 3.1ml/kg(GR II); 4.6ml/kg(GR III). The R _PFC after 4 hrs was 52±2.6%(GR I), 45±6.7%(GR II); 74±2.4%(GR III). We conclude that E_L profile is dependent upon initial PFC dose and time after dosing. Thus, in addition to ventilation strategy and positioning, E_L profile should be considered in order to optimize replacement dosing. Table

Table 1 No caption available.