Application of continuous veno-venous hemofiltration in patients with acute respiratory distress syndrome

Abstract

To investigate the changes of interleukin (IL)-6 serum level in patients with acute respiratory distress syndrome (ARDS) and the effects of continuous renal replacement therapy (CRRT) on IL-6 level and its clinical significance. Forty ARDS patients were randomly divided into 2 equal groups: Group A undergoing conventional treatment and Group B receiving conventional treatment plus CRRT at onset of ARDS. Serum IL-6 level was measured by enzyme linked immunosorbent assay (ELISA) at the onset (0 h) and 12, 24, 48, and 72 hours later. Dynamic APACHEII score was also evaluated at the time points of 0, 24, 48, and 72 h. The incidence of ventilator-associated pneumonia (VAP), intensive care unit (ICU) mortality rate, duration of total mechanical ventilation, and ICU stay were assessed. Twenty-five healthy examinees were used as controls. The serum IL-6 level of the whole ARDS patients was significantly higher then that of the normal controls (P < 0.01), and the serum IL-6 level of the ARDS patients who died was significantly higher than that of the ARDS patients who survived (P < 0.01). The IL-6 serum level was correlated well with the APACHEIIscore either in the survival subgroup or the non-survival subgroup (for the former: r = 0.560 P = 0.008, and for the latter: r = 0.518 P = 0.023). Group B, contrary to Group A, had persistently decreased serum IL-6 levels and APACHEII scores at the onset and during the progression of ARDS (all P < 0.05). The incidence of VAP in Group B was 45%, significantly lower than that in Group A (80%, P = 0.022) while the ICU mortality rate didn't differ between the two groups (40% vs 55%, P = 0.342). The duration of total mechanical ventilation and ICU stay of the Group B patients who underwent early CRRT were (12 +/- 5) days and (16 +/- 5) days respectively, both significantly shorter than those of Group A patients [(16 +/- 5) days, P = 0.027 and (19 +/- 5) days, P = 0.030]. The elevated serum IL-6 level in ARDS patients seems to be correlated well with the severity of lung injury, and appears to be a good marker to judge the prognosis of the disease combined with APACHEII score. In the early phase of ARDS, CRRT can decrease the high serum level of IL-6, shorten the duration of total mechanical ventilation and ICU stay, and decrease the incidence of VAP. Removal of the circulating proinflammatory cytokines by CRRT may be one of the most vital mechanisms to treat ARDS.