Continuous veno-venous hemofiltration improves hemodynamics in septic shock with acute renal failure without modifying TNFalpha and IL6 plasma concentrations.

BACKGROUND

Continuous hemofiltration improves hemodynamics in critically ill patients by removing cytokines from the plasma. The mechanism, however, remains to be clarified since recent studies show conflicting findings. The present study was therefore designed to evaluate hemodynamic changes and kinetics of tumor necrosis factor (TNF)alpha, interleukin (IL)1beta and IL6 in patients with septic shock and acute renal failure (ARF) undergoing continuous veno-venous hemofiltration (CWHF), over a 24-hour period.

METHODS

Eleven patients admitted to the ICU for septic shock with ARF were investigated with radial artery and pulmonary artery catheterization during isovolemic CWHF using AN69 hemofilters at a blood flow rate of 240 mL/min and ultrafiltration 1.65 +/- 0.33 L/h. Hemodynamic measurements (mean arterial pressure, right arterial pressure, pulmonary artery pressure, pulmonary vascular resistance, systemic vascular resistance, cardiac output and tissue oxygenation indeces) were obtained before and after 2h, 4h, 6h, 12h and 24 h of CVVHF. Blood samples from the pre- and postfilter lines and ultrafiltrate samples were collected for the radioimmunoassay of TNFalpha, IL1beta and IL6 before and at 2h, 4h, 6h, 12h and 24h.

RESULTS

During CVVHF, mean arterial pressure rose from 67 +/- 7 mm Hg to 89 +/- 5 mm Hg (p < 0.05) and indexed systemic vascular resistance from 711 +/- 153 dyne.s.cm(-5)/m2 to 1,200 +/- 100 dyne.s.cm(-5)/m2 (p < 0.05). Serum lactate and oxygen consumption did not change. Mean arterial pressure and systemic vascular resistance were not correlated to the lowering of body temperature during CVVHF. Significant clearance of IL6 was achieved, but not of TNFa, though the plasma concentrations of both cytokines were unaffected throughout the study. IL1beta was not detectable. Two patients were discharged alive with normal renal function.

CONCLUSION

In patients with septic shock and ARF, CVVHF improves mean arterial pressure and systemic vascular resistance. This effect does not appear to be related to the removal of cytokines. The effect of CVVHF on mortality and morbidity in the long term, in septic shock has still to be established.