Importance of increased ultrafiltration volume and impact on mortality: sepsis and cytokine story and the role of continuous veno-venous haemofiltration

While in end-stage renal disease dialysis dose correlates with morbidity an d mortality, this correlation is less evident in acute renal failure. In sp ite of a poor literature in the field, a few recent papers seem to suggest that an increase in treatment dose may result in an improved Outcome Of cri tically ill patients affected by acute renal failure. This improvement appe ars to plateau at a certain level of dialysis dose in the general populatio n while, in septic patients, the correlation between treatment dose and out come continues linearly. These results suggest that, while the 'renal dose' of renal replacement therapy has a threshold beyond which further improvem ents cannot be expected, the 'septic dose' of renal replacement therapy is probably higher and may provide benefits beyond simple blood purification f rom uremic toxins. This approach is in agreement with the recently proposed 'peak concentration hypothesis', which suggests that sepsis may derive fro m a complete derangement of the immunological response, featuring simultane ous peaks of pro- and anti-inflammatory mediators. This would explain the s ystemic inflammatory syndrome and the cell hyporesponsiveness of the septic patient and, at the same time, would explain the beneficial effects of new therapies such as high volume hemofiltration, coupled plasmafiltration ads orption and dialysis with hyperpermeable membranes. These therapies could b e able to reduce the peaks of the pro- and anti-inflammatory substances cir culating during the syndrome, leading to a less severe degree of inflammati on and immunodepression. Curr Opin Nephrol Hypertens 10:755-761. (C) 2001 L ippincott Williams & Wilkins.