The immunological effects of continuous veno-venous haemodiafiltration in critically ill patients

Background: Haemodynamic instability is common in septic patients with acut e renal failure. Continuous veno-venous haemodiafiltration (CVVHD) is there fore used as an alternative to conventional haemodialysis. Haemodialysis is associated with an activation of the immune system. The aim of the present study was to test the hypothesis that initiation of CVVHD influences the i mmune system with release of proinflammatory cytokines followed by a decrea se in granulocyte activation, as assessed by the expression of adhesion mol ecules. Results: Fifteen patients were included. Mean Acute Physiology and Chronic Health Evaluation-2 score before CVVHD was 19 (range 8-27). Mean duration o f CVVHD treatment was 9 days (1-21 days). Tumour necrosis factor-alpha and interleukin-8 were detectable in plasma in all patients, whereas interleuki n-10 was detectable only in a few patients. Proinflammatory and anti-inflam matory cytokines were detected in the ultrafiltrate. Large intraindividual and interindividual variations were demonstrated for all of the immunologic al parameters studied. Conclusion: The hypothesis that CVVHD induces the release of proinflammator y cytokines followed by a decrease in granulocyte activation was not confir med in the present study. The heterogeneous group of patients studied, with different underlying diseases and various durations of illness before the start of CVVHD, might have contributed to the difficulty in demonstrating t he proposed immunological effect of CVVHD.