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Abstract
Adequate dialysis is defined as the effective dose that is able to achieve the stated objectives. Dialysis dose may be measured by urea reduction ratio (URR) which is defined as the fractional decrease in blood urea nitrogen. URR is considered to be less accurate as a true measure of dialysis dose since it is also significantly influenced by the volume of fluid removed during treatment. Another utility is urea kinetic modeling (Kt/V) which can be defined as the amount of urea clearance (K) multiplied by time (t) and divided by urea distribution volume (V) and its derivatives.Anemia is a common comorbidity in hemodialysis patients. Anemia is a result of reduction in erythropoiesis which is caused by reduced renal production of erythropoietin (EPO) and by resistance of bone marrow cells to this hormone; in addition, shortened survival of red blood cells often is present. Large cohort studies found a clear relationship between the degree of anemia and dialysis dose. However, none of these studies have been able to discriminate the role of different dialysis modalities in addition to that of adequacy. A direct relationship was described between hematocrit level and URR after adjustment for other factors.In hemodialysis patients, the prevalence of malnutrition increases from 18 to 75 %, although this value depends on the criteria used to define malnutrition. A noncontrolled, unrandomized study has suggested that the nutritional status of patients can be improved by increasing the dose of conventional hemodialysis and/or by using biocompatible membranes.Hypertension is very common in patients undergoing regular conventional hemodialysis treatment. There is an important interaction between hemodialysis process and administration of antihypertensives.
Increasing delivered dialysis dose showed that both systolic and diastolic BP decreased statistically significantly. It was recognized that hypertension in HD patients could be difficult to control, but that normal BP values could be achieved by “adequate” dialysis and ultrafiltration in 80–90% of patients.
Hypertension is also affected by various dialysis regimens. For example, with SDHD, which increases the frequency but not the total dialysis time, the intra and interdialytic changes are much smaller, and this treatment is associated with improved blood pressure control and a reduction in left ventricular mass.