OXYGEN DYNAMICS DURING PARTIAL LIQUID VENTILATION IN A SHEEP MODEL OFSEVERE RESPIRATORY-FAILURE

Background. We evaluated the relationship of dose of perflubron and ga s tidal volume to oxygen dynamics during partial liquid ventilation in the setting of respiratory failure. Methods. Lung injury was induced in 16 sheep by using right atrial injection of 0.15 ml/kg oleic acid. Animals were ventilated with 15 ml/kg gas tidal volume and stabilized. Animal were then divided into three groups: (1) gas ventilation with a tidal volume of 15 ml/kg (control, GV, n = 5); (2) partial liquid ve ntilation at a gas tidal volume of 15 ml/kg with 10 ml/kg incremental pulmonary dosage of perflubron from 10 to 50 ml/kg (best fill, BF, n = 6); (3) administration of 35 ml/kg perflubron pulmonary dose with 5 m l/kg incremental increase in gas tidal volume from 10 to 30 ml/kg (bes t tidal volume, BTV, n = 5). Results. Arterial oxygen saturation incre ased with increasing dose of perflubron and gas tidal volume (BF, p = 0.01; BTV, p = 0.001). A simultaneous trend toward a reduction in card iac index was observed with increasing dose of perflubron (BF, p = 0.0 1). Maximal increase in mixed venous oxygen saturation was observed in the BF and BTV groups at a cumulative perflubron dose of 40 ml/kg and a gas tidal volume of 20 ml/kg, respectively. Conclusions. In this sh eep lung injury model oxygenation improves with incremental increases in perflubron dose or gas tidal volume, and the mixed venous oxygen sa turation appears to be optimal at a cumulative perflubron dose of 40 m l/kg and a gas tidal volume of 20 ml/kg.