Residual kidney function (RKF) is a powerful indicator of residual renal functional capacity that eliminates uremic toxins and fluid in hemodialysis patients. The purpose of our study was to investigate the influence of hydrating status on residual renal function in patients with CKD 5HD. Methods. A prospective observational study included 60 hemodialysis patients with CKD VD. All patients were examined - taken general and biochemical blood tests, determined the level of urea and creatinine in the daily urine. RKF was evaluated by urine volume, residual KT / V and KRU. Water balance was measured and evaluated using BCM-monitor. Results.During the analysis of BCM data, hyperhydration (OH / ECW above 15%) was revealed in 15 among all patients included in the study, which amounted to 25%. A statistically significant difference between patients who were hyperhydrated and normohydrated was found in relative (OH / ECW) and absolute hydration (OH), ECW, and ultrafiltration rates. Thus, in the group of hyperhydrated patients, the average relative hydration rate was 14.3% lower compared to normohydrated patients (p < 0.001) and absolute hydration by 2.6 l (p < 0.001). In further analysis, no significant difference between two groups was found in the indicators characterizing the RKF, namely, between the level of urine output, KRU, KT / Vren. The level of ultrafiltration in the group with normal hydration is 900 ml lower than that with hyperhydration (p < 0.005). In study the influence of indicators of hydration status such as OH, OH / ECW, TBW, ECW, ICW on RKF indices no reliable correlation of the above mentioned values ​​with diuresis, KRU, KT / Vren (p > 0.05) was found. A positive correlation was found between KRU, diuresis and KT / Vren, indicating that with increasing diuresis the KRU value and KT / Vren increase (p < 0.001). The same relationship was found between diuresis and KT / Vren, p < 0.001. An analysis of the relationship between absolute and relative hydration with dialysis efficacy (eKT / V) revealed that dialysis efficacy decreases with increase of hydratation in CKD 5HD patients (p < 0.05). Conclusions. The results obtained in our study indicate that the indicators of hydration status at baseline do not allow to find out an influence of them on the baseline level of RKF (diuresis, KRU and KT / Vren) in patients with CKD 5HD. Issues of the influence of hydration status on changes in RKF during the observation will be addressed in the following reports.

Even the length of hospital stay was longer in the LR group (30 VS 23 days; p ¼ 0,06). Patients receiving vaccination against hepatitis B were more important in the group ER (58,5% VS 38,5%; p ¼ 0,003). However, there was no difference between the 2 groups according to the mortality risk during the first 3 months and even the first year of dialysis. Conclusions: Early referral may be beneficial because it allows dialysis planification and treatment of the complications of progressive uremia. But, Early death on HD seems not to be associated with late referral to a nephrologist.

Understanding of changes in water compartments during hemodialysis (HD) is an important part of ensuring the effectiveness of the procedure and minimizing both intra- and post-dialysis complications.  The purpose of our study was to investigate the direction of changes in water sectors in patients with CKD 5D with preserved residual kidney function (RKF) and without RKF. Methods. Prospective observational study enrolled 88 hemodialysis (HD) patients. All patients performed laboratory examinations and measurements of water balance using the BCM monitor before HD, hourly after the start, and 30 minutes after the end of the session. Depending on the presence of residual kidney function, patients were divided into two groups. The first group with RKF included 52 patients, the second - without RKF - 36. Results. Analysis of water balance parameters allowed to conclude that 26 patients (26.13%) were hyperhydrated (OH/ECW above 15%), including 13 (36,11%) in the group without RKF and 10 (19,2%) - in the group with the preserved RKF. There was no statistically significant difference in the groups. When comparing baseline values between groups of patients, it was found that in the group with preserved RKF the albumin level was significantly higher at 8.94% (p<0.05), levels of phosphorus and potassium were lower by 18.27% and 20.24%, respectively. There was no statistically significant difference between other clinical parameters in the groups. Subsequent analysis of the water balance indicators allowed establishing a reliable positive correlation between the level of ultrafiltration (UV) and total body water (TBW). The higher the UV level, the higher the ECW (p < 0.05). Similar results were obtained when analyzing the relationship between extracellular fluid (ECW) and UV (p < 0,001). As a result of the correlation analysis between the level of UV and diuresis, the mean inverse correlation relationship is shown, which shows - the lower the diuresis, the higher the level of ultrafiltration (p < 0,001). During HD the TBW (ΔTBW = 1.5 ± 1.8) and ECW (ΔECW = 1.92 ± 0.85) progressively decrease, the ICW compartment is practically unchanged (ΔICW = -0.17 ± 0.89). In patients with preserved RKF the change in ECW is significantly lower comparatively with the group without RKF (p <0.05). Conclusions. Obtained data indicate that the clinical evaluation of hyperhydration is not always adequate. The obtained results confirm the fact that the presence of RKF provides better phosphorus and potassium levels control in patients with CKD. During HD the removal of fluid occurs directly from the extracellular space, in the group with the RKF to a lesser extent, indicating that the presence of diuresis provides a lower volume of OH, TBW, ECW before HD session, and therefore the level of ultrafiltration appears to be less. Thus the RKF also provides better control of water balance. The results of the dynamics of water sector changes during HD can be used to assess the refilling in the future.

In the field of hemodialysis technologies, as in other fields of medicine, evolutionary changes are constantly taking place. The innovations are driven by unachieved clinical outcomes and desire to improve the quality of care of patients with CKD 5D. Recent advances in dialysis techniques resulted in the possibility to expand the permeability of dialysis membranes for a wider spectrum of uremic toxins that lead to the enhancement of long-term outcomes improving quality of life and reducing the mortality rate of dialysis patients. The inadequacy of existent dialysis techniques, at least in part, is due to the chronic accumulation of organic retention solutes of middle and large molecules, which are poorly or even not removed during dialysis. A gradual improvement in the elimination of uremic toxins is observed as a result of the development of new alternative approaches of hemodialysis therapy, such as high-flux hemodialysis, hemodiafiltration, expanded hemodialysis (HDx). However, some techniques have had limited success due to a host number of organizational, technological, financial and human factors. Expanded hemodialysis offers a novel blood purification technology in removal of the large spectrum of uremic toxins, in particular large medium molecules, due to the new structure of the dialysis membrane. There are a number of studies that prove the potential benefits of a new method of dialysis therapy over the previous ones, suggesting a reduction in cardiovascular mortality, vascular calcification and inflammation. In addition, there is evidence of a positive effect of HDx on the quality of life in dialysis patients. In particular, to minimize the manifestations of skin itching, restless legs syndrome, asthenic syndrome.

The work is a literature review. Residual kidney function (RKF) is one of the crucial indicators of mortality and quality of life in patients with chronic kidney disease. Residual renal function provides better control of hydration, blood pressure, clearance of substances with low and middleweight, anemia, Ca/P metabolism, chronic inflammation. However, approaches to preservation of RKF in dialysis patients have been studied not enough, the importance of RKF preservation is underlined. The wide range of predictors of RKF loss are presented in the article, approaches to measurement of RKF, the relationship between level and presence of RKF with survival and mortality of patients with CKD 5D were analyzed. The possibility of RKF preservation and extension using different approaches by correction of dialysis prescription were estimated. There is no standardized method for applying incremental hemodialysis in practice. Onceto twice-weekly hemodialysis regimens are often used randomly, without knowing the benefit for current patient or how to escalate the dialysis dose if RKF declines over time. It is important to change the HD/HDF prescription according to the range of RRF using objective data.