LIQUID VENTILATION PROVIDES UNIFORM-DISTRIBUTION OF PERFLUOROCARBON IN THE SETTING OF RESPIRATORY-FAILURE

Background. We evaluated the effect of perfluorocarbon liquid ventilat ion (LV) on gas exchange and pulmonary function in the setting of resp iratory failure and the distribution of the ventilating medium during LV when compared to gas ventilation (GV). Methods. Ten sheep, 17.3 +/- 4.2 kg in weight, underwent oleic acid induction of the lung injury f ollowed by either GV (n = 5) or perfluorocarbon LV (n = 5). After 1 ho ur animals were killed, and chest computed tomographic (CT) imaging wa s performed. Average CT attenuation number was assessed as an indicato r of the distribution of gas or perfluorocarbon in the dependent (post erior) and nondependent (anterior) zones of the lung (air = -1000; sof t tissue = 0; perfluorocarbon = +2300 Hounsfield units [H]). Result. S ignificant increases in PaO2 (LV = 298 +/- 76 mm Hg, GV = 43 +/- 18 mm Hg, p < 0.001), SvO(2) (LV = 74% +/- 6%, GV = 32% +/- 18% p < 0.01), and lung compliance (LV = 1.65 +/- 0.50 ml/cm H2O/kg, GV = 0.58 +/- 0. 06 ml/cm H2O/kg, p < 0.01) were noted. Ct attenuation data showed the presence of minimal gas ventilation in the dependent regions during GV although the nondependent regions remained well aerated (CT attenuati on number during GV: ND = -654 +/- 160 H; D = -92 +/- 160 H, p < 0.000 1). During LV, there was a fairly homogenous distribution of perfluoro carbon in the lungs (CT attenuation number during LV: D = 1071 +/- 330 Hounsfield units; ND = 1112 +/- 287 Hounsfield units; p = 0.240). Lun g biopsy analysis in the LV animals was consistent with a reduction in intraalveolar hemorrhage, intraalveolar edema, and the inflammatory i nfiltrate. Conclusions. On the basis of the data, we conclude that in this lung injury model, (1) the distribution of the ventilating medium is uniform during LV when compared to GV, (2) LV improves gas exchang e and pulmonary function, and (3) histologic evidence of lung injury i s reduced after LV when compared to GV.