ObjectiveTo compare compliance and end-expiratory lung volume during reexpansion of normal and surfactant-deficient ex vivo atelectatic lungs with either gas or total liquid ventilation.DesignControlled, animal study using an ex vivo lung preparation.SettingA research laboratory at a university medical center.SubjectsThirty-six adult cats, weighing 2.5 to 4.0 kg.InterventionsHeparin (300 U/kg) was administered, cats were killed, and lungs were excised en bloc. Normal lungs and salinelavaged, surfactant-deficient lungs were allowed to passively collapse and remain atelectatic for 1 hr. Lungs then were placed in a plethysmogragh and ventilated for 2 hrs with standardized volumes of either room air or perfluorocarbon. Static pulmonary compliance and end-expiratory lung volume were measured every 30 mins.Measurements and Main ResultsReexpansion of normal atelectatic lungs with total liquid ventilation was associated with an 11-fold increase in end-expiratory lung volume when compared with the increase in end-expiratory lung volume observed with gas ventilation (total liquid ventilation 50 plus minus 14 mL, gas ventilation 4 plus minus 9 mL, p less than .0001). The difference was even more pronounced in the surfactant-deficient lungs with an approximate 19-fold increase in end-expiratory lung volume observed in the total liquid ventilated group, compared with the gas ventilated group (total liquid ventilation 44 plus minus 17 mL, gas ventilation 2 plus minus 8 mL, p equals .0001). Total liquid ventilation was associated with an increase in pulmonary compliance when compared with gas ventilation in both normal and surfactant-deficient lungs (normal: gas ventilation 6 plus minus 1 mL/cm H2O, total liquid ventilation 14 plus minus 4 mL/cm H2O, p less than .0001; surfactant-deficient: gas ventilation 4 plus minus 1 mL/cm H2O, total liquid ventilation 9 plus minus 3 mL/cm H2O, p less than .01).ConclusionsEnd-expiratory lung volume and static compliance are increased significantly following attempted reexpansion with total liquid ventilation when compared with gas ventilation in normal and surfactant-deficient, atelectatic lungs. The ability of total liquid ventilation to enhance recruitment of atelectatic lung regions may be an important means by which gas exchange is improved during total liquid ventilation when compared with gas ventilation in the setting of respiratory failure.(Crit Care Med 1996; 24:268-273)