Role of ventilation strategy on perfluorochemical evaporation from the lungs

To study the effect of ventilation strategy on perfluorochemical (PFC) elim ination profile (evaporative loss profile; E-L), 6 mL/kg of perflubron were instilled into anesthetized normal rabbits. The strategy was to maintain m inute ventilation (V-E, in ml/min) in three groups: (V) over dot E-L, (low- range (V) over dot E, 208 +/- 2), (V) over dot E-M, (midrange (V) over dot E, 250 +/- 9), and (V) over dot E-H, thigh-range (V) over dot E, 293 +/- 1) over 4 h. In three other groups, respiratory rate (RR, breaths/min) was co ntrolled at 20, 30, or 50 with a constant (V) over dot E and adjusted tidal volume. PFC content in the expired gas was measured, and E, was calculated . There was a significant (V) over dot E- and time-dependent effect on E-L Initially, percent PFC saturation and loss rate decreased in the (V) over d ot E-H > (V) over dot E-M > (V) over dot E-L groups, but by 3 h the lower p ercent PFC saturation resulted in a loss rate such that (V) over dot E-H < (V) over dot E-M < (V) over dot E-L at 4 h. For the groups at constant ire, there was a significant time effect on E, but no RR effect. In conclusion, E, profile is dependent on (V) over dot E with little effect of the RR-tid al volume combination. Thus measurement of E, and VE should be considered f or the replacement dosing schemes during partial liquid ventilation.