No abstract

To examine how patient survival substantiates dialysis adequacy, 20-year actuarial survival experience was calculated for 445 unselected hemodialysis (HD) patients (97 patients accepted on a temporary basis--and usually kept on their regular dialysis scheme--were left out). The dose of dialysis has been the same and unchanged for all patients since beginning: 24 square meter hours of Kiil dialysis (cuprophane) per week with acetate buffered dialysate. KT/V mean (SD) was 1.67 (0.41). Six months after starting dialysis, 98% of patients were normotensive and off all blood pressure (BP) medication. The mean population hematocrit, excluding the only 6 patients receiving erythropoietin supplementation, was 28%. Survival rate was 87% at 5 years, 75% at 10 years, 55% at 15 years, and 43% at 20 years of HD. The satisfactory control of BP without using potentially toxic BP drugs and the higher than usual dose of dialysis are two possible explanations for survival data better than usually reported. We suggest that patient survival should be considered as the best overall index of adequacy of dialysis.

The total amount of sodium present in the body controls the extracellular volume. In advanced renal failure, sodium balance becomes positive and the extracellular volume expands. This leads to hypertension, and vascular changes that lead to adverse cardiovascular consequences in dialysis patients. Controlling the body sodium content and the extracellular volume allows one to better control hypertension and its consequences. This can be achieved by reducing the sodium input (sodium dietary restriction and reasonably low sodium dialysate) and/or by increasing the sodium output (ultrafiltration by convection). The discontinuous nature of hemodialysis causes saw-tooth volume fluctuations. This has led to the concept of dry weight (DW), a crucial component of dialysis adequacy. Assessment and achievement of DW is feasible on pure clinical grounds. But its relative lack of accuracy (and the physicians' progressive lack of interest in bedside examination) has led to several nonclinical methods of assessing DW in an effort to improve the assessment of fluid status in dialysis patients.

A drastic reduction in hemodialysis (HD) time has been based on the dialysis dose measurement in terms of urea Kt/V exclusively and on the use of high efficiency dialysers. It was subtly coupled to a de-emphasis of the use of HD to normalize blood pressure. In Tassin we have maintained long slow HD with an overall excellent patient survival. We analyze the influence of the different factors of this survival: the place of dry weight and blood pressure control without use of antihypertensive medication is emphasized, and the role of dialysis dose and nutrition is discussed. Adequacy should be defined in terms of these additive conditions. Long slow HD allows one to fulfill these conditions easily. Shortening of dialysis time should not interfere with the control of blood pressure.

Unsatisfactory control of blood pressure (BP) leading to an increased rate of cardiovascular events is the main cause of mortality in haemodialysis. BP control has deteriorated since haemodialysis session times have been reduced. Inadequate BP control most often is due to a failure to achieve and maintain dry weight. Dry weight and normotension have been gradually omitted in the goals of dialysis, satisfactory dialysis being reduced to an 'adequate' urea Kt/V. Ideal dry body weight needs a reappraisal. What is dry weight? How should it be clinically assessed, established and maintained in patients? The problems encountered in estimating dry weight can be solved at the bedside in most cases. The additional laboratory, echography and impedancemetry methods are research tools that hopefully can be made simpler and lower in cost so they can be used everyday at the bedside. In the mean time, with the exception of ambulatory blood pressure measurement, one must rely on careful and repeated clinical observation to determine and maintain dry weight.