Enhanced solute removal with intermittent, in-center, 8-hour nocturnal hemodialysis

Nocturnal home hemodialysis in children: Advantages, implementation, and barriers

Chronic kidney disease and end-stage renal disease (ESRD) in children are major health concerns worldwide with increasing incidence and prevalence. Renal replacement therapies and kidney transplants have remarkably improved the management of patients with ESRD in both adult and pediatric populations. Kidney transplant has the best patient outcomes, but many a time it has a considerable waiting period. In the meantime, the majority of patients with pediatric ESRD are dependent on dialysis. The conventionally utilized hemodialysis regimen is the three times weekly, in-center hemodialysis. Many studies have demonstrated the unfavorable long-term morbidity associated with the conventional regimen. Intensified dialysis programs, which include extended nocturnal hemodialysis or short daily hemodialysis, are being increasingly advocated over the past two decades. In addition to having much better clinical outcomes as compared with the conventional regimen, the flexibility to provide dialysis at home serves as a great incentive. PubMed/Medline, Embase and Cochrane databases for literature on nocturnal home hemodialysis in children with ESRD were extensively searched. Contrary to the noticeable literature available on adult home hemodialysis, a small number of studies exist in the pediatric population. In this review, the benefits, implementation and associated barriers of nocturnal home hemodialysis in children were addressed.

Association between conversion to in-center nocturnal hemodialysis and right ventricular remodeling

Background

In-center nocturnal hemodialysis (INHD) is associated with favorable left ventricular (LV) remodeling. Although right ventricular (RV) structure and function carry prognostic significance, the impact of dialysis intensification on RV is unknown. Our objectives were to evaluate changes in RV mass index (MI), end-diastolic volume index (EDVI), end-systolic volume index (ESVI) and ejection fraction (EF) after conversion to INHD and their relationship with LV remodeling.

Methods

Of 67 conventional hemodialysis (CHD, 4 h/session, three times/week) patients, 30 continued on CHD and 37 converted to INHD (7-8 h/session, three times/week). Cardiac magnetic resonance imaging was performed at baseline and 1 year using a standardized protocol; an experienced and blinded reader performed RV measurements.

Results

At 1 year there were significant reductions in RVMI {-2.1 g/m2 [95% confidence interval (CI) -3.8 to - 0.4], P = 0.017}, RVEDVI [-9.5 mL/m2 (95% CI - 16.3 to - 2.6), P = 0.008] and RVESVI [-6.2 mL/m2 (95% CI - 10.9 to - 1.6), P = 0.011] in the INHD group; no significant changes were observed in the CHD group. Between-group comparisons showed significantly greater reduction of RVESVI [-7.9 mL/m2 (95% CI - 14.9 to - 0.9), P = 0.03] in the INHD group, a nonsignificant trend toward greater reduction in RVEDVI and no significant difference in RVMI and RVEF changes. There was significant correlation between LV and RV in terms of changes in mass index (MI) (r = 0.46), EDVI (r = 0.73), ESVI (r = 0.7) and EF (r = 0.38) over 1 year (all P < 0.01).

Conclusions

Conversion to INHD was associated with a significant reduction of RVESVI. Temporal changes in RV mass, volume and function paralleled those of LV. Our findings support the need for larger, longer-term studies to confirm favorable RV remodeling and determine its impact on clinical outcomes.

In-center nocturnal hemodialysis

Dialysis intensification from conventional regimens (typically thrice weekly, 4 hours per session) is increasingly utilized with the intent of improving the cardiovascular health and quality of life of chronic dialysis recipients. While home nocturnal hemodialysis offers the opportunity for maximal intensification of dialysis, it is inaccessible to the majority of dialysis recipients who are unable to self-administer hemodialysis in their own homes. In-center nocturnal hemodialysis (INHD) permits the intensification of conventional hemodialysis with the benefits of nursing support and supervision in addition to freedom from dialysis during productive daytime hours. Although no randomized trials have evaluated the relative merits of INHD, preliminary data indicate that INHD is a viable option that may confer a variety of benefits for chronic dialysis recipients.

Influence of high-flux hemodialysis and hemodiafiltration on serum C-terminal agrin fragment levels in end-stage renal disease patients

C-terminal agrin fragment (CAF, 22 kDa) has been shown to be a promising new rapid biomarker for kidney function. This study evaluated the influence of hemodialysis (HD) and hemodiafiltration (HDF) treatment on serum CAF concentrations in patients with end-stage renal disease (ESRD). A total of 36 patients with ESRD undergoing chronic HD/HDF treatment were enrolled (21 high-flux-HD/Fx60 membrane, 7 high-flux-HD/Elisio19H membrane, and 8 HDF/Elisio19H membrane). On a midweek session, blood samples were obtained before, at halftime, and post-treatment. Dialysate samples were obtained 4 times during treatment. Serum and dialysate CAF, cystatin C, urea, and creatinine concentrations were measured. Reduction ratios (RRs), total solute removal, overall dialytic clearance, and instantaneous dialytic clearance at halftime were calculated and compared. Although HD/Elisio19H and HDF/Elisio19H treatments significantly reduced CAF concentrations (RR 46.6 ± 9.1% and 57.6 ± 11.7%, respectively, P = 0.018 and P = 0.001), HD/Fx60 treatment did not remove CAF from serum (RR 2.4 ± 15.4%, P = 0.25), there was no relevant CAF detection in dialysate. In the HD/Fx60 group, the RR of CAF was significantly lower compared with cystatin C, urea, and creatinine, in which significant removal was detected (37.9 ± 14.8%, 65.0 ± 10.7%, and 56.0 ± 9.8%, respectively, P < 0.001). CAF is a new biomarker for kidney function whose serum concentration is not influenced by conventional high-flux HD using Fx60 membrane. It might therefore represent a promising dialysis-independent biomarker for evaluation of kidney function, for example, in acute kidney failure.

Phosphate removal model: an observational study of low-flux dialyzers in conventional hemodialysis therapy

Precise assessing phosphate removal by hemodialysis (HD) is important to improve phosphate control in patients on maintenance HD. We reported a simple noninvasive model to estimate phosphate removal within a 4-hour HD. One hundred sixty-five patients who underwent HD 4 hours per session using low-flux dialyzers made of polysulfone (1.2 m(2)) or triacetate (1.3 m(2)) were enrolled. Blood flows varied from 180 to 300 mL/min. Effluent dialysate samples were collected during the 4-hour HD treatment to measure the total phosphate removal. Predialysis levels of serum phosphate, potassium, hematocrit, intact parathyroid hormone, total carbon dioxide (TCO(2)), alkaline phosphatase, clinical and dialysis characteristics were obtained. One hundred thirty-five observations were randomly selected for model building and the remaining 30 for model validation. Total amount of phosphate removal within the 4-hour HD was mostly 15-30 mmol. A primary model (model 1) predicting total phosphate removal was Tpo(4)  = 79.6 × C(45) (mmol/L) - 0.023 × age (years) + 0.065 × weight (kg) - 0.12 × TCO(2) (mmol/L) + 0.05 × clearance (mL/min) - 3.44, where C(45) was phosphate concentration in spent dialysate measured at the 45 minute of HD and clearance was phosphate clearance of dialyzer in vitro conditions offered by manufacturer's data sheet. Since the parameter TCO(2) needed serum sample for measurement, we further derived a noninvasive model (model 2):Tpo(4)  = 80.3 × C(45)  - 0.024 × age + 0.07 × weight + 0.06 × clearance - 8.14. Coefficient of determination, root mean square error, and residual plots showed the appropriateness of two models. Model validation further suggested good and similar predictive ability of them. This study derived a noninvasive model to predict phosphate removal. It applies to patients treated by 4-hour HD under similar conditions.

Survival with three-times weekly in-center nocturnal versus conventional hemodialysis

Whether the duration of hemodialysis treatments improves outcomes remains controversial. Here, we evaluated survival and clinical changes associated with converting from conventional hemodialysis (mean=3.75 h/treatment) to in-center nocturnal hemodialysis (mean=7.85 h/treatment). All 959 consecutive patients who initiated nocturnal hemodialysis for the first time in 77 Fresenius Medical Care facilities during 2006 and 2007 were eligible. We used Cox models to compare risk for mortality during 2 years of follow-up in a 1:3 propensity score-matched cohort of 746 nocturnal and 2062 control patients on conventional hemodialysis. Two-year mortality was 19% among nocturnal hemodialysis patients compared with 27% among conventional patients. Nocturnal hemodialysis associated with a 25% reduction in the risk for death after adjustment for age, body mass index, and dialysis vintage (hazard ratio=0.75, 95% confidence interval=0.61-0.91, P=0.004). With respect to clinical features, interdialytic weight gain, albumin, hemoglobin, dialysis dose, and calcium increased on nocturnal therapy, whereas postdialysis weight, predialysis systolic blood pressure, ultrafiltration rate, phosphorus, and white blood cell count declined (all P<0.001). In summary, notwithstanding the possibility of residual selection bias, conversion to treatment with nocturnal hemodialysis associates with favorable clinical features, laboratory biomarkers, and improved survival compared with propensity score-matched controls. The potential impact of extended treatment time on clinical outcomes while maintaining a three times per week hemodialysis schedule requires evaluation in future clinical trials.

Regression of left ventricular mass following conversion from conventional hemodialysis to thrice weekly in-centre nocturnal hemodialysis

Background

Increased left ventricular mass (LVM) is associated with adverse outcomes in patients receiving chronic hemodialysis. Among patients receiving conventional hemodialysis (CHD, 3×/week, 4 hrs/session), we evaluated whether dialysis intensification with in-centre nocturnal hemodialysis (INHD, 3×/week, 7-8 hrs/session in the dialysis unit) was associated with regression of LVM.

Methods

We conducted a retrospective cohort study of CHD recipients who converted to INHD and received INHD for at least 6 months. LVM on the first echocardiogram performed at least 6 months post-conversion was compared to LVM pre-conversion. In a secondary analysis, we examined echocardiograms performed at least 12 months after starting INHD. The effect of conversion to INHD on LVM over time was also evaluated using a longitudinal analysis that incorporated all LVM data on patients with 2 or more echocardiograms.

Results

Thirty-seven patients were eligible for the primary analysis. Mean age at conversion was 49 ± 12 yrs and 30% were women. Mean pre-conversion LVM was 219 ± 66 g and following conversion, LVM declined by 32 ± 58 g (p = 0.002). Among patients whose follow-up echocardiogram occurred at least 12 months following conversion, LVM declined by 40 ± 56 g (p = 0.0004). The rate of change of LVM decreased significantly from 0.4 g/yr before conversion, to -11.7 g/yr following conversion to INHD (p < 0.0001).

Conclusion

Conversion to INHD is associated with a significant regression in LVM, which may portend a more favourable cardiovascular outcome. Our preliminary findings support the need for randomized controlled trials to definitively evaluate the cardiovascular effects of INHD.

Selectively increasing the clearance of protein-bound uremic solutes

BACKGROUND

The toxicity of bound solutes could be better evaluated if we could adjust the clearance of such solutes independent of unbound solutes. This study assessed whether bound solute clearances can be increased while maintaining urea clearance constant during the extended hours of nocturnal dialysis.

METHODS

Nine patients on thrice-weekly nocturnal dialysis underwent two experimental dialysis treatments 1 week apart. The experimental treatments were designed to provide the same urea clearance while providing widely different bound solute clearance. One treatment employed a large dialyzer and high dialyzate flow rate (Qd) of 800 mL/min while blood flow (Qb) was 270 mL/min. The other treatment employed a smaller dialyzer and Qd of 300 mL/min while Qb was 350 mL/min.

RESULTS

Treatment with the large dialyzer and higher Qd greatly increased the clearances of the bound solutes p-cresol sulfate (PCS: 27±9 versus 14±6 mL/min) and indoxyl sulfate (IS: 26±8 versus 14±5 mL/min) without altering the clearance of urea (204±20 versus 193±16 mL/min). Increasing PCS and IS clearances increased the removal of these solutes (PCS: 375±200 versus 207±86 mg/session; IS: 201±137 versus 153±74 mg/session), while urea removal was not different.

CONCLUSIONS

The removal of bound solutes can thus be increased by raising the dialyzate flow and dialyzer size above the low levels sufficient to achieve target Kt/V(urea) during extended treatment. Selectively increasing the clearance of bound solutes provides a potential means to test their toxicity.

In-center nocturnal hemodialysis performed thrice-weekly--a provider's perspective

Favorable clinical outcomes related to morbidity, mortality, patient well-being, laboratory biomarkers, and medication use have been reported with in-center nocturnal hemodialysis (INHD); nevertheless, it is not entirely clear how much patient selection or physiologic mechanisms related to better fluid management and phosphorus (and calcium) metabolism may explain these outcomes. There are indications that INHD may be a preferred treatment option in specific cases, such as in patients with high interdialytic weight gain, poor tolerance to high ultrafiltration rate, hyperphosphatemia, or for those patients who work or go to school during the day. In the era of the new prospective payment system where quality standards become intertwined with reimbursement, an INHD program may be a useful method to help attain quality goals in facilities that have patients with unfavorable case-mix. The experience of the past decade has shown INHD to be safe and well tolerated by patients. The growth of INHD therapy is a testament to sustainability and feasibility of this treatment option. Prospective clinical trials are needed in this area. If the promise of INHD is fulfilled, it may also prove to be a valuable option for potential success of Accountable Care Organizations where providers need to assume responsibility for more patient-centered care and improvement in clinical outcomes. In summary, based on the current experience, INHD is a viable and valuable option as an additional, alternative hemodialysis (HD) regimen to conventional HD.

Kinetic model of phosphorus mobilization during and after short and conventional hemodialysis

BACKGROUND AND OBJECTIVES

The kinetics of plasma phosphorus (inorganic phosphorus or phosphate) during hemodialysis treatments cannot be explained by conventional one- or two-compartment models; previous approaches have been limited by assuming that the distribution of phosphorus is confined to classical intracellular and extracellular fluid compartments. In this study a novel pseudo one-compartment model, including phosphorus mobilization from a large second compartment, was proposed and evaluated.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Clinical data were obtained during a crossover study where 22 chronic hemodialysis patients underwent both short (2-hour) and conventional (4-hour) hemodialysis sessions. The model estimated two patient-specific parameters, phosphorus mobilization clearance and phosphorus central distribution volume, by fitting frequent intradialytic and postdialytic plasma phosphorus concentrations using nonlinear regression.

RESULTS

Phosphorus mobilization clearances varied among patients (45 to 208 ml/min), but estimates during short (98 ± 44 ml/min, mean ± SD) and conventional (99 ± 47 ml/min) sessions were not different (P = 0.74) and correlated with each other (concordance correlation coefficient ρ(c) of 0.85). Phosphorus central distribution volumes for each patient (short: 11.0 ± 4.2 L and conventional: 11.9 ± 3.8 L) were also correlated (ρ(c) of 0.45).

CONCLUSIONS

The reproducibility of patient-specific parameters during short and conventional hemodialysis treatments suggests that a pseudo one-compartment model is robust and can describe plasma phosphorus kinetics under conditions of clinical interest.

Effects of thrice-weekly in-center nocturnal vs. conventional hemodialysis on integrated backscatter of myocardial tissue

Ultrasonic tissue characterization with integrated backscatter (IBS) offers a promising method for the noninvasive assessment of myocardial fibrosis and contractile performance. The aim of this study was to investigate the effect of thrice-weekly in-center nocturnal hemodialysis (INHD) and conventional hemodialysis (CHD) on myocardial fibrosis and left ventricular function in end-stage renal disease patients. Thirty-two INHD and 58 matched CHD patients were enrolled; baseline and 12-month measures of blood pressure (BP), serum calcium and phosphorus, echocardiographic left ventricular mass index (LVMI) and left ventricular function, the myocardial calibrated IBS (C-IBS), and systodiastolic cyclical variations in IBS (CV-IBS) were collected. The baseline characteristics were similar between groups, except that serum phosphorus and calcium × phosphorus were higher in the INHD group. At 12-month follow-up, there was a significant decrease in the mean C-IBS (-20.2 ± 3.7 to -28.1 ± 4.0 dB, P<0.01) and a significant increase in CV-IBS (5.0 ± 1.5 to 7.1 ± 1.6 dB, P<0.01) in INHD patients. Multivariate analysis showed that the mean C-IBS was positively related to SBP, DBP, LVMI, serum phosphorus, and left atrial volume index and inversely related to midwall fractional shortening, transmitral E/A ratio, and E(m) . The mean CV-IBS was positively correlated with left ventricular midwall fractional shortening, E/A ratio, E(m) and inversely correlated with SBP, DBP, LVMI, serum phosphorus, E/E(m) , and left atrial volume index. There was no significant change in the mean C-IBS, mean CV-IBS, and LVMI in the CHD group. Compared with CHD, INHD improves myocardial fibrosis and left ventricular function, and control of serum phosphorus is associated with the improvement of myocardial fibrosis. Improvement of myocardial fibrosis contributes to the reduction of left ventricle hypertrophy.