Background: There is debate as to whether, in patients with acute lung injury, continuous renal replacement therapy has beneficial effects on pulmonary gas exchange by mechanisms other than fluid removal. Because continuous renal replacement therapy is associated with potential morbidity and mortality, it seems unethical to perform a randomized trial in patients with acute lung injury without renal failure. Therefore, the effects of continuous venovenous haemodiafiltration with zero volume balance on gas exchange were evaluated in patients with acute renal failure and acute lung injury. Because haemofilter conditions should be comparable between patients, we opted for an evaluation of the effects during a 24-h period. Results of this trial can guide future studies in non-renal patients with acute lung injury.
Methods: In all 37 patients with acute renal failure and acute lung injury, treated with continuous venovenous haemodiafiltration with zero fluid balance during a 1 year period, ventilatory and haemodynamic parameters were measured every 8 h during the 24 h preceding therapy and during the first 24 h of therapy.
Results: We found a slight, although not statistically significant, increase in the PaO(2)/FIO(2) ratio and the oxygenation index, in the total group of patients, and in the subgroups of patients with acute lung injury of extrapulmonary and pulmonary causes.
Conclusions: During the first 24 h of treatment, continuous venovenous haemodiafiltration with zero volume balance did not result in a significant improvement of the respiratory status in patients with acute renal failure and acute lung injury, nor in the subgroups of patients with acute lung injury with extrapulmonary causes.