Effects of high volume continous veno-venous hemofiltration in cardiac surgery patients with renal failure

Acute Renal Failure following cardio-pulmonary bypass carries a high mortality. It has been shown that hemofiltration improves cardiac function during and after cardiopulmonary bypass by removal of myocardial depressant substances and/or cytokines. The aim of this study was to evaluate the safety and efficiency of HV-CVVH with a highly permeable filter, started early in patients with acute renal failure following heart surgery. 36 cardio-surgical patients (mean age 67) were included. Most of the patients were suffering from acute renal failure as a consequence of a low-output syndrome after cardiac surgery. We used cellulose triacetate membrane, surface area 1.9 m2, cutoff 50.000 D. An ultrafiltrate flow was 50-80 ml/min. Parameters of renal function, changes in inotropic support, arterial blood pressure, pulmonary gas exchange (PO2/FiO2 ratio) before and after hemofiltration treatment, were retrospectively analyzed. Values of serum creatinine levels, serum urea levels and doses of dopamine, noradrenaline, enoximone, as well as, values of positive end expiratory pressure and the PaO2/FiO2 ratio before the first, and after or at the end of the last run of HV-CVVH, were compared by the paired t-test. We observed a low incidence of complications related to hemofiltration. Hemofiltration normalized serum urea and creatinine levels within 24 hours. The need for inotropic support after HV-CVVH was lower than before. The PaO2/FiO2 ratio was significantly higher after HV-CVVH than before. In the 29 patients in whom renal function was recovered, the median time of recovery was 96 hours and in 86% of these patients the function recovered within 10 days. Hospital mortality was 30.3%. High volume continuous venovenous hemofiltration is a safe and effective treatment in post cardiac surgery patients. HV-CVVH seems to improve the cardiac and respiratory functions.

Keywords: Hemofiltration, Multiple Organ Failure, renal failure, cardiac surgery