Hemodialysis Time and Kt/V: Less May Be Better.

ABSTRACT

Current guidelines focus on conventional dialysis defined as 3-5 hours, three times per week, and suggest that longer or more frequent dialysis be considered. This paper presents the case for considering that shorter or less frequent dialysis should also be considered. More frequent and/or longer dialysis facilitates control of fluid overload, blood pressure, and phosphate levels. These benefits will require time to translate into probable hard outcome improvement. Patients are unlikely to participate in productive or pleasurable activities while undergoing dialysis in center or traveling to treatment. So any increase in dialysis time or frequency, during awake hours, will result in an immediate and quantifiable reduction in quality of life. Conventional measures of dialysis adequacy consider only urea clearance. This poorly reflects middle molecule clearance, renal function, and management of fluid and phosphate overload, all of which have a greater impact on outcome than urea clearance. Fluid, phosphate, and uremic toxin overload may be better and less invasively controlled by continuous means such as dietary modification, binders, and preserving renal function. Bioimpedance, blood volume monitoring, and lung ultrasound provide means for improved control of fluid homeostasis. The probability of renal function recovery or preservation is increased by avoiding dehydration. An ideal strategy would be to preserve renal function and employ as little dialysis as possible (if it cannot be avoided altogether). Fluid overload, blood pressure, uremic toxin, and phosphate levels would be monitored and controlled using any means available, preferably by less invasive means than dialysis. Kt/V is useful in controlling the prescribed dose of dialysis, but the achievement of a universal target should not be an end in itself.