From the above discussion, the advantages of long dialysis to the patients are obvious: better tolerance of dialysis, better control of blood pressure, better removal of MMs, better rehabilitation, and longer survival. The average ratio of patients to dialysis personnel is 3-4 to 1 in the US. Because of better tolerance of dialysis with fewer hypotensive episodes, the same ratio in Tassin is 6 to 1 . Thus, the financial disadvantage of longer dialysis may be blunted by a reduced staff requirement. Long di alysis sessions may be performed at home without increased cost to the providers.
Kt/Vurea Should Be Abandoned as a Measure of
The acceptance of this index was based on insufficient data and their false interpretation. In the NCDS study the tendency toward lower morbidity with longer dialysis duration was rejected as statistically insignificant because p was 0.06 instead of 0.05 (sic!). However, the power of this study was low because of an insufficient number of patients, short study duration (52 weeks) and disregard of residual renal function, which must have been substantial as many patients were of short vintage. It is worth repeating that the absence of evidence is not the evidence of absence. Combining dialyzer urea clearance (K), dialysis duration (t) and urea distribution volume (V) in one formula and accepting this formula as a measure of dialysis adequacy has brought disastrous consequences. The formula suggests that it is possible to decrease t as long as K is proportionately increased, but this is not true. For instance, increasing dialyzer urea clearance (K) may compensate for shorter dialysis time (t) regarding urea removal, but it cannot compensate for the dialysis tolerance depending on the rate of ultrafiltration, nor has it reflected removal of bigger molecules. A very small urea distribution volume (V) will provide large Kt/Vurea in malnourished patients, even if their dialysis duration is short and dialyzer clearances are low. One can imagine that following only Kt/Vurea, patients loosing appetite, poorly nourished, may maintain this index of dialysis adequacy continuously loosing weight and urea distribution volume (V) until their demise. The Kt/V formula is misleading and should be abandoned as a measure of dialysis quality. Would any aircraft pilot use an altimeter showing the wrong altitude?
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