Duration and adequacy of dialysis. Overview: the science is easy, the ethic is difficult

Because of physiologic, technical, and practical limits, short dialysis is probably associated with higher mortality when compared with longer dialysis, even when dialysis efficiency is maintained with a proportionately higher clearance. The optimal dialysis efficiency measured as KT/V (or better expressed as mean standardized urea clearance in ml/min) for hemodialysis, remains unknown, but it is not unreasonable to assume that either a KT/V of 3 or a mean standardized urea clearance of 30 ml/min is optimal, and certainly better than the presently used KT/V of 1.2 to 1.8. To achieve KT/Vs on this order, a 70 kg patient will need at least 7 hours of dialysis 3 times per week. This gives rise to an ethical problem: Should one give many patients short dialysis, or fewer patients longer dialysis? This is a question to which no easy ethical solution can be found.