Partial liquid ventilation combined with two different gas ventilation strategies in acute lung injury in piglets

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Objectives

To investigate the effects of two different gas ventilation strategies during partial liquid ventilation (PLV) on gas exchange and lung mechanics in acute lung injury.

Design

Prospective, randomized, experimental study.

Setting

University research laboratory.

Subjects

Fourteen piglets weighing 8.9± 0.2 kg.

Interventions

Acute lung injury was induced by the infusion of oleic acid and repeated lung lavages with 0.9% NaCl (20 ml/kg). After a stabilization period of 30 min the animals were randomized to two groups with different PEEP levels and tidal volumes (Group A: Vt >12.5 ml/kg, PEEP 6 cmH₂O; Group B: Vt 9 ml/kg, PEEP 12 cmH₂O). The pre-oxygenated and warmed perfluorocarbon liquid (30 ml/kg) was instilled into the trachea over 15 min without changing the ventilator settings.

Measurements and main results

Airway pressures, tidal volumes, static respiratory compliance, inspiratory and expiratory airway resistances and arterial blood gases were measured. Data were obtained at baseline, after lung injury and at 60 and 120 min of PLV. See Table 1.

Data analysis

Values are given as mean ± SEM. Comparisons were made by ANOVA for repeated measures. A P-value of <0.05 was considered significant. The infusion of oleic acid (0.07 ml/kg) combined with five lung lavages induced a significant reduction of PaO₂/FiO₂ from 486± 24 torr to 60± 3.8 torr (P<0.01).

Conclusions

During PLV both gas ventilation strategies significantly improved oxygenation in an animal model of acute lung injury. Static compliance of the respiratory system was not different between both gas ventilation strategies. Inspiratory airway resistance was significantly higher during the low PEEP-high Vt gas ventilation strategy, whereas the high PEEP-low VT strategy resulted in significantly higher PaCO₂ values.

Table 1 Blood gases and respiratory variables during PLV with two different strategies of gas ventilation.