The contribution of arterio-venous extracorporeal lung assist to gas exchange in a porcine model of lavage-induced acute lung injury.

This prospective large-animal study was performed to evaluate the contribution of arterio-venous extracorporeal lung assist (AV-ECLA) to pulmonary gas exchange in a porcine lavage-induced acute lung injury model. Fifteen healthy female pigs, weighing 50.3 +/- 3.8 kg (mean +/- SD), were included. After induction of general anaesthesia and controlled ventilation, an arterial line and a pulmonary artery catheter were inserted. Saline lung lavage was performed until the PaO2 decreased to 51 +/- 16 mmHg. After a stabilization period of 60 min, the femoral artery and vein were cannulated and a low-resistance membrane lung was interposed. Under apnoeic oxygenation, variations of sweep-gas flow were performed every 20 min in order to evaluate the membrane lung's efficacy, in terms of carbon dioxide (CO2) removal and oxygen (O2) uptake. Although AV-ECLA is highly effective in eliminating CO2, if combined with apnoeic oxygenation, normocapnia was not achievable. AV-ECLA's contribution to oxygenation during severe hypoxemia was antagonized by a significant increase in the pulmonary shunt fraction.