Continuous venovenous hemofiltration improves arterial oxygenation in endotoxin-induced lung injury in pigs

Background: Hypoxemia is common in septic acute lung failure. Therapy is ma inly supportive, and most trials using specific inhibitors of key inflammat ory mediators (ie., tumor necrosis factor a, interleukin 1) have failed to prove beneficial. The authors investigated if a nonspecific blood purificat ion technique, using zero-balanced high-volume continuous venovenous hemofi ltration (CVVH), might improve arterial oxygenation in a fluid-resuscitated porcine model of endotoxin-induced acute lung injury Methods. Piglets of both sexes weighing 25-30 kg were anesthetized and mech anically ventilated. After baseline measurements, animals received an intra venous infusion of 0.5 mg/kg endotoxin (Escherichia coli lipopolysaccharide ). One hour after endotoxin, animals were randomly assigned to either treat ment with CVVH (endotoxin + hemofiltration, n = 6) or spontaneous course (e ndotoxin, n = 6). At 4 h after randomization, animals were killed. Hemofilt ration was performed from femoral vein to femoral vein using a standard cir cuit with an EF60 polysulphone hemofilter. Results. Endotoxin challenge induced arterial hypoxemia, an increase in pea k inspiratory pressure, pulmonary hypertension, and systemic hypotension. T reatment with CVVH did not improve systemic or pulmonary hemodynamics. Howe ver, arterial oxygenation was increased in endotoxin-challenged animal at 5 h after completion of endotoxin infusion, as compared with animals not rec eiving CVVH (arterial oxygen tension, 268 +/- 33 vs. 176 +/- 67 mmHg, respe ctively, P < 0.01). In addition, treatment with CVVH attenuated the endotox in-induced increase in peak inspiratory pressure and increased lung complia nce. Conclusion: These results suggest that nonspecific blood purification with high-volume CVVH improves arterial oxygenation and lung function in endotox in-induced acute lung injury in pigs, independent of improved hemodynamics, fluid removal, or body temperature.