Background: Despite increasing knowledge about partial
liquid ventilation (PLV), the optimal dose of perfluorocarbon (PFC) is
not yet established. Because there exist normal regions in the lung
with ARDS and because PLV in the normal lung results in worsened gas
exchange, we postulated that the optimal dose of PFC for PLV may be
less than the functional residual capacity (FRC) dose in the lung with
Design and setting: Animal study at
the Asan Institute for Life Sciences, Seoul, Korea.
Subjects: Twelve rabbits in which dependent lung-dominant
lung injury was created by a modified saline solution lavage.
Interventions: PLV performed at six different doses of
perfluorodecalin in sequence (3, 6, 9, 12, 15, and 18 mL/kg every 15
Measurements and results: Our modified saline
solution lavage induced atelectasis and hemorrhage confined to the
dependent lung with severe hypoxia
(Pao2/fraction of inspired oxygen = 37 ± 6
mm Hg). Peak airway pressure (Ppeak) and inspiratory pause pressure
(Ppause) with PLV were lower at doses of 3 to 15 mL/kg (all
p < 0.05), but not different at a dose of 18 mL/kg, when compared
with gas ventilation. Ppeak increased at doses of 12, 15, and 18 mL/kg,
when each was compared with the preceding PFC dose. At increasing PFC
doses, the change in the elastic component of airway pressure (Ppause
after minus Ppause before) was negative until the dose of 9 mL/kg, but
was positive at doses of 12 mL/kg and above. The change in the
resistive component ([Ppeak minus Ppause] after minus [Ppeak minus
Ppause] before) was negative until the dose of 6 mL/kg, but was
positive at the dose ≥ 9 mL/kg.
Respiratory mechanics during PLV for dependent lung–dominant lung
injury were optimal at a PFC dose less than the FRC.