Do shorter hemodialyses increase the risk of death?

Improvement in technology has made it possible to deliver a high dialysis dose in a shorter period of time. Studies of the relationship between dialysis treatment duration and mortality have revealed that the risk of death increased significantly as the treatment time was reduced. The longer duration and increased frequency of dialysis achieve an excellent clearance of smalland middleweight toxins, enable equilibration of tissue and vascular compartments, improve appetite and permit liberalization of diet, while gentle ultrafiltration allows for better control of hypertension. Better clearance of uremic toxins, normalization of cellular and extracellular volume, and improved nutrition result in a significant decrease in morbidity and mortality of dialyzed patients. With most of dialyzers in use, adequate hemodialysis can be delivered in 4 to 5 hours, especially in a setting of maximal blood and high dialysate flow, and low access recirculation. Although controversial, the preliminary evidence available favor the use of a biocompatible membrane and more frequent or prolonged dialysis to ensure adequate removal of smalland middle molecular weight toxins, yet preventing the loss of essential solutes.