Opinion: How Should Dialysis Fluid Be Individualized for the Chronic Hemodialysis Patient?

Low dialysate sodium in children and young adults on maintenance hemodialysis: a prospective, randomized, crossover study

BACKGROUND

The optimal dialysate sodium concentration (dNa) in children on hemodialysis (HD) is unknown. The aim of this study was to compare the effect on interdialytic weight gain (IDWG) and blood pressure (BP) of a low (135 mmol/l) and standard dNa (138 mmol/l) in children and young adults on maintenance HD.

METHODS

This prospective single-blind randomized crossover study consisted of a randomized sequence of two phases: "standard dNa" of 138 mmol/L and "low dNa" of 135 mmol/L. Each phase lasted 4 weeks. Inclusion criteria were age < 25 years, hypertension, pre-HD serum Na (sNa) ≥ 130 mmol/L, and occurrence of symptoms in less than 25% of sessions. Primary outcomes were pre-HD systolic and diastolic BP and IDWG.

RESULTS

Fifteen patients were recruited, mean age 17.8 ± 4.4 years. Pre-HD SBP and DBP were not different between the two treatments. Mean IDWG was significantly lower with low dNa than with standard dNa: 2.12 ± 1.39% vs. 2.77 ± 1.53%, respectively (p = 0.008). The first-hour refill index (a volume index based on blood-volume monitoring) was significantly lower with dNa 135 mmol/L (p = 0.018). The mean Na gradient (dNa-sNa) was - 2.53 ± 2.4 mmol/L with dNa 135 mmol/L and 0.17 ± 2.8 mmol/L with dNa 138 mmol/L (p = 0.0001). The incidence of symptomatic sessions was similar (1.0% vs. 1.0%).

CONCLUSIONS

In a selected population of hypertensive pediatric and young adult HD patients, a dNa of 135 mmol/L was associated with a significant reduction of IDWG compared with a dNa of 138 mmol/L. Furthermore, long-term studies are needed to investigate the effect of lowering dNa on BP. A higher resolution version of the Graphical abstract is available as Supplementary information.

A first proof-of-concept for the non-invasive, time-efficient measurement of the plasma sodium concentration for individualized dialysis

Dialysis-induced changes in plasma sodium concentration may cause undesirable side effects. To prevent these, the sodium content in dialysis fluid has to be individualized based on the patient's plasma sodium concentration. In this paper, we describe a simple conductivity based method for measuring the plasma sodium concentration. The method is based on performing a bypass during which the residual volume on the dialysate side of the dialyzer at least partially adopts the sodium concentration on the blood side. The conductivity at dialysate outlet of the dialyzer after the end of bypass corresponds to the sodium concentration. We show that already 14 s of bypass are sufficient to subsequently measure a conductivity that correlates with the blood-side sodium concentration. Thus, the short bypass method allows a time saving of 88% compared to the long bypass of 120 s. In vitro experiments with bovine blood show that plasma sodium concentration can be non-invasively and time-efficiently measured during dialysis. Bland Altman analysis reveals a bias of 0.28 mmol/l and limits of agreement of -3.17 and 3.74 mmol/l for the long bypass. For the short bypass, bias is 0.09 mmol/l and limits are -3.90 and 4.08 mmol/l. Since the method presented is based on established conductivity cells, no additional sensors are required, so that the method could be easily implemented in dialysis machines. In future, performing a bypass at the beginning of a treatment may be used to adjust the composition of dialysis fluid individually for each patient.

Effects of Individualized Dialysate Sodium Prescription in Hemodialysis - Results from a Prospective Interventional Trial

INTRODUCTION

Individualized dialysate sodium prescription does affect weight gain, blood pressure (BP), and intradialytic complications. A prospective interventional trial (Dialysate Individualised Sodium (DISO) trial) was conducted to study this issue in Indian patients.

METHODS

Forty patients on thrice-weekly maintenance hemodialysis (HD) for at least 6 weeks were enrolled. The study was performed in two different phases. In the first phase, 12 consecutive HD sessions were done with a standard dialysate sodium concentration of 140 mEq/L. In the second phase, 12 consecutive HD sessions were done with dialysate sodium concentration set to individualized value (mean of pre-HD sodium concentration multiplied by Donnan coefficient of 0.95). Differences in pre- and post-HD sodium, interdialytic weight gain (IDWG), pre- and post-HD BP, thirst scores, and intradialytic adverse events during both phases were assessed.

RESULTS

The mean age of patients was 45.65 years (24 males, 16 females). The mean serum pre-HD sodium level was 138.7 ± 1.7 meq/L in the standard phase and 138.2 ± 2.6meq/L in the individualized phase (P = 0.229). In the standard phase, the mean IDWG was 2.64 ± 1.56 kg and 2.13 ± 0.99 kg in the individualized phase (P = 0.008). The mean pre-HD systolic BP was 138 ± 18 mmHg and 134 ± 17 mmHg in the standard and individualized phases (P = 0.008). There was no difference in intradialytic symptoms, hypotensive episodes or requirement of interventions. Hypertension episodes occurred at a mean value of 2.2 and 1.2 in the standard and individualized phases, respectively (P = 0.010).

CONCLUSION

The use of individualized dialysate sodium level is safe and results in lower IDWG, pre-HD systolic BP, and intradialytic hypertension in patients on HD.

Low dialysate sodium levels for chronic haemodialysis

BACKGROUND

Cardiovascular (CV) disease is the leading cause of death in dialysis patients, and strongly associated with fluid overload and hypertension. It is plausible that low dialysate [Na+] may decrease total body sodium content, thereby reducing fluid overload and hypertension, and ultimately reducing CV morbidity and mortality.

OBJECTIVES

This review evaluated harms and benefits of using a low (< 138 mM) dialysate [Na+] for maintenance haemodialysis (HD) patients.

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Register of Studies up to 7 August 2018 through contact with the Information Specialist using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Register (ICTRP) Search Portal and ClinicalTrials.gov.

SELECTION CRITERIA

Randomised controlled trials (RCTs), both parallel and cross-over, of low (< 138 mM) versus neutral (138 to 140 mM) or high (> 140 mM) dialysate [Na+] for maintenance HD patients were included.

DATA COLLECTION AND ANALYSIS

Two investigators independently screened studies for inclusion and extracted data. Statistical analyses were performed using random effects models, and results expressed as risk ratios (RR) for dichotomous outcomes, and mean differences (MD) or standardised MD (SMD) for continuous outcomes, with 95% confidence intervals (CI). Confidence in the evidence was assessed using GRADE.

MAIN RESULTS

We included 12 studies randomising 310 patients, with data available for 266 patients after dropout. All but one study evaluated a fixed concentration of low dialysate [Na+], and one profiled dialysate [Na+]. Three studies were parallel group, and the remaining nine cross-over. Of the latter, only two used a washout between intervention and control periods. Most studies were short-term with a median (interquartile range) follow-up of 3 (3, 8.5) weeks. Two were of a single HD session, and two of a single week's HD. Half of the studies were conducted prior to 2000, and five reported use of obsolete HD practices. Risks of bias in the included studies were often high or unclear, lowering confidence in the results.Compared to neutral or high dialysate [Na+], low dialysate [Na+] had the following effects on "efficacy" endpoints: reduced interdialytic weight gain (10 studies: MD -0.35 kg, 95% CI -0.18 to -0.51; high certainty evidence); probably reduced predialysis mean arterial blood pressure (BP) (4 studies: MD -3.58 mmHg, 95% CI -5.46 to -1.69; moderate certainty evidence); probably reduced postdialysis mean arterial BP (MAP) (4 studies: MD -3.26 mmHg, 95% CI -1.70 to -4.82; moderate certainty evidence); probably reduced predialysis serum [Na+] (7 studies: MD -1.69 mM, 95% CI -2.36 to -1.02; moderate certainty evidence); may have reduced antihypertensive medication (2 studies: SMD -0.67 SD, 95% CI -1.07 to -0.28; low certainty evidence). Compared to neutral or high dialysate [Na+], low dialysate [Na+] had the following effects on "safety" endpoints: probably increased intradialytic hypotension events (9 studies: RR 1.56, 95% 1.17 to 2.07; moderate certainty evidence); probably increased intradialytic cramps (6 studies: RR 1.77, 95% 1.15 to 2.73; moderate certainty evidence).Compared to neutral or high dialysate [Na+], low dialysate [Na+] may make little or no difference to: intradialytic BP (2 studies: MD for systolic BP -3.99 mmHg, 95% CI -17.96 to 9.99; diastolic BP 1.33 mmHg, 95% CI -6.29 to 8.95; low certainty evidence); interdialytic BP (2 studies:, MD for systolic BP 0.17 mmHg, 95% CI -5.42 to 5.08; diastolic BP -2.00 mmHg, 95% CI -4.84 to 0.84; low certainty evidence); dietary salt intake (2 studies: MD -0.21g/d, 95% CI -0.48 to 0.06; low certainty evidence).Due to very low quality of evidence, it is uncertain whether low dialysate [Na+] changed extracellular fluid status, venous tone, arterial vascular resistance, left ventricular mass or volumes, thirst or fatigue. Studies did not examine cardiovascular or all-cause mortality, cardiovascular events, or hospitalisation.

AUTHORS' CONCLUSIONS

It is likely that low dialysate [Na+] reduces intradialytic weight gain and BP, which are effects directionally associated with improved outcomes. However, the intervention probably also increases intradialytic hypotension and reduces serum [Na+], effects that are associated with increased mortality risk. The effect of the intervention on overall patient health and well-being is unknown. Further evidence is needed in the form of longer-term studies in contemporary settings, evaluating end-organ effects in small-scale mechanistic studies using optimal methods, and clinical outcomes in large-scale multicentre RCTs.

Sodium Prescription in the Prevention of Intradialytic Hypotension: New Insights into an Old Concept

Background: Sodium prescription in patients with intradialytic hypotension remains a challenge for the attending nephrologist, as it increases dialysate conductivity in hypotension-prone patients, thereby adding to dietary sodium levels. Methods: New sodium prescription strategies are now available, including the use of a mathematical model to compute the sodium mass to be removed during dialysis as a physiological controller. Results: This review describes the sodium load of patients with end-stage renal disease on chronic hemodialysis (HD) and discusses 2 strategies to remove excess sodium in patients prone to intradialytic hypotension, namely, Profiled HD and the hemodiafiltration Aequilibrium System. Conclusion: The Profiled HD and Aequilibrium System trial both proved effective in counteracting intradialytic hypotension.

The Dialysis Sodium Gradient: A Modifiable Risk Factor for Fluid Overload

Background

Fluid overload in patients on conventional hemodialysis is a frequent complication, associated with increased cardiovascular morbidity and mortality. The dialysate sodium prescription is a potential modifiable risk factor. Our primary objective was to describe associations between dialysate-to-serum sodium gradient and parameters of fluid status. A secondary objective was to evaluate the 6-month risk of hospitalization and mortality in relation to sodium gradient.

Methods

We performed a cross-sectional study of 110 prevalent conventional hemodialysis patients at a single center. The associations of sodium gradient with interdialytic weight gain index (IDWG%), ultrafiltration (UF) rate, and blood pressure (BP) were analyzed.

Results

The mean serum sodium gradient was 4.6 ± 3.6 mEq/L. There was a direct correlation between sodium gradient and IDWG% (r = 0.48, p < 0.01) as well as UF rate (r = 0.44, p < 0.01). In a logistic regression model, a 1 mEq/L higher sodium gradient was associated with increased risk of IDWG% >3% (OR 1.33, p < 0.01) and increased risk of UF rate >10 mL/kg/h (OR 1.16, p = 0.03), but there were no associations with intradialytic hypotension, intradialytic hypertension or BP. No significant differences were found with 6-month hospitalization or mortality risk in relation to sodium gradient.

Conclusion

A higher sodium gradient was associated with significant increases in IDWG and UF rates, known to be associated with poor outcomes, but was not associated with intradialytic hypotension. Individualizing the dialysate sodium prescription to minimize sodium gap may lead to less fluid overload in conventional hemodialysis patients.

The choice of dialysate sodium is influenced by hemodialysis frequency and duration: what should it be and for what modality?

Cardiovascular disease is the leading cause of mortality in hemodialysis patients. A chronic state of volume and pressure overload contributes, and central to this is the net sodium balance over the course of a hemodialysis. Of recent interest is the contribution of the dialysate sodium concentration (Dial-Na+) to clinical outcomes. Abundant evidence confirms that in thrice-weekly conventional hemodialysis, higher Dial-Na+ associates with increased intradialytic weight gain, blood pressure, and cardiovascular morbidity and mortality. On the other hand, low Dial-Na+ associates with intradialytic hypotension in the same patient population. However, the effect of Dial-Na+ in short hours daily hemodialysis (SHD; often referred to as "quotidian" dialysis), or nocturnal dialysis (FHND) is less well studied. Increased frequency and duration of exposure to a diffusive sodium gradient modulate the way in which DPNa+ alters interdialytic weight gain, predialysis blood pressure, and intradialytic change in blood pressure. Furthermore, increased dialysis frequency appears to decrease the predialysis plasma sodium setpoint (SP), which is considered stable in conventional thrice-weekly patients. This review discusses criteria to determine optimal Dial-Na+ in conventional, SHD and FHND patients, and identifies areas for future research.

Dialysate sodium prescription and blood pressure in hemodialysis patients

BACKGROUND

Diffusive sodium removal has been recommended to control hypertension in hemodialysis patients. Recent evidence on hospitalizations and mortality, however, challenged the benefit of lower dialysate sodium prescriptions and ignited a debate in the dialysis community. We therefore studied the relationship between dialysate sodium and blood pressure over the longer term.

METHODS

We used multiply adjusted linear mixed models to estimate the association between dialysate sodium and predialysis systolic blood pressure (SBP) as well as change in SBP (delta SBP; postdialysis minus predialysis) in 23,962 patients from the international Dialysis Outcomes and Practice Patterns Study.

RESULTS

We found that 43% of hemodialysis facilities had variable (individualized) dialysate sodium prescriptions (125-155 mEq/L), whereas 57% had uniform dialysate sodium prescriptions (135-145 mEq/L) for ≥90% patients. Between-group comparisons of these 2 facility types suggested that dialysate sodium, when variably prescribed, might have been used to modify predialysis SBP (P interaction = 0.01) and perhaps delta SBP levels (P interaction = 0.08). Within facilities not prone to indication bias, because dialysate sodium was not variable, higher uniform dialysate sodium (per 2 mEq/L) was associated with slightly higher SBP (+0.9 mm Hg, 95% confidence interval (CI) = 0.1-1.6 among all patients; +1.7 mm Hg, 95% CI = 0.1-3.2 among patients not treated with blood pressure medication) and no increase in delta SBP.

CONCLUSIONS

Patients assigned to hemodialysis facilities with uniformly higher dialysate sodium do not have markedly higher predialysis SBP, providing rather limited support for lowering dialysate sodium to control hypertension, particularly in view of hospitalization and mortality risks associated with lower dialysate sodium.

Optimal dialysate sodium-what is the evidence?

Oligo-anuric patients with end-stage kidney disease are dependent on hemodialysis to achieve and maintain the desired goal of euvolemia. The dialysis prescription, in addition to sodium and fluid restriction, is therefore a critically important factor in the care of hemodialysis patients. Various dialysate sodium concentrations have been favored throughout the history of dialysis, but the "optimal" concentration remains unclear. In this manuscript, we examine the historical context of changes to the dialysate sodium prescription, review the evidence of its associated effects, discuss 'individualization' of dialysate sodium, and highlight the need for definitive trials that are powered for important clinical outcomes.

Role of dialysis sodium gradient on intradialytic hypertension: an observational study

INTRODUCTION

The causes of intradialytic hypertension (IDHyper) are not well understood and this condition can complicate the clinical management of hemodialysis (HD) patients.

AIM

To evaluate the potential role of intradialytic sodium gradient (NaG) on blood pressure values and IDHyper during HD.

PATIENTS AND METHODS

206 prevalent HD patients on 3 times weekly HD treatment for at least 6 months (dialytic vintage 6-240 months) followed at our institution were studied. Mean age was 68 ± 14 years, 129 were men. For 2 consecutive months (24 HD sessions) after the start of observation, the following variables were evaluated in predialysis after the long interdialysis interval: pre-HD plasma sodium (pNa, mmol/l) and potassium (pK, mmol/l) concentrations (mean value of 8 determinations), pre- and post-HD systolic (SBP, mm Hg) and diastolic (DBP, mm Hg) blood pressure, dry body weight (dBW, kg), interdialytic weight gain (IDWG, kg), ultrafiltration rate (UFR, ml/kg/h), dialysis dose (Kt/V), protein catabolic rate (PCRn, g/kg/day), hemoglobin (Hb, g/dl). SBP, DBP, IDWG, UFR are the mean values of the 24 HD sessions. 76% of patients were on antihypertensive therapy, 171 patients were on bicarbonate HD, and 35 on HDF. Dialysate Na concentration was set at 140 mmol/l in all patients. Duration of HD and the blood and dialysate flow rate were kept constant during observation.

STATISTICAL ANALYSIS

Data are expressed as mean ± SD; linear and multiple regression analysis and t test for unpaired data were employed. Significant differences were defined as p < 0.05.

RESULTS

Pre-HD pNa was 138.1 ± 2.3 mmol/l, pK 5.0 ± 0.4 mmol/l, dBW 67 ± 14 kg, IDWG 2.9 ± 0.8 kg, UFR 11.2 ± 3.7 ml/kg/h, Kt/V 1.43 ± 0.18, PCRn 1.13 ± 0.17 g/kg/day, and Hb 11.2 ± 0.8 g/dl. Pre- and post-HD SBP values were 139 ± 13 and 134 ± 12 mm Hg (p < 0.0001); pre- and post-HD DBP did not change significantly. A dialysis Na gradient (NaG) (dialysate Na - pre-HD pNa) was calculated, as well as the delta of SBP (ΔSBP) (post-HD SBP - pre-HD SBP). IDHyper was defined as ΔSBP >0. A significant direct correlation was found between NaG and ΔSBP (p < 0.0001) and multiple regression analysis with ΔSBP as dependent variable confirmed the strong correlation with NaG (p < 0.00001). According to ΔSBP behavior, 171 patients (83%) had a decrease or no change in post-HD SBP (group 1; no IDHyper); 35 patients (17%) increased their post-HD SBP (group 2; IDHyper). NaG values were significantly greater in patients in group 2 (group 1: 1.5 ± 2.2 vs. group 2: 3.3 ± 2.5, p < 0.0001).

CONCLUSIONS

This study shows that the intradialytic ΔSBP is independently and strongly associated with the dialytic NaG. The more positive the NaG (net intradialytic Na gain), the more positive the ΔSBP and IDHyper.

Significance of interdialytic weight gain versus chronic volume overload: consensus opinion

Predialysis volume overload is the sum of interdialytic weight gain (IDWG) and residual postdialysis volume overload. It results mostly from failure to achieve an adequate volume status at the end of the dialysis session. Recent developments in bioimpedance spectroscopy and possibly relative plasma volume monitoring permit noninvasive volume status assessment in hemodialysis patients. A large proportion of patients have previously been shown to be chronically volume overloaded predialysis (defined as >15% above 'normal' extracellular fluid volume, equivalent to >2.5 liters on average), and to exhibit a more than twofold increased mortality risk. By contrast, the magnitude of the mortality risk associated with IDWG is much smaller and only evident with very large weight gains. Here we review the available evidence on volume overload and IDWG, and question the use of IDWG as an indicator of 'nonadherence' by describing its association with postdialysis volume depletion. We also demonstrate the relationship between IDWG, volume overload and predialysis serum sodium concentration, and comment on salt intake. Discriminating between volume overload and IDWG will likely lead to a more appropriate management of fluid withdrawal during dialysis. Consensually, the present authors agree that this discrimination should be among the primary goals for dialysis caretakers today. In consequence, we recommend objective measures of volume status beyond mere evaluations of IDWG.

Sodium balance in maintenance hemodialysis

Sodium is the principal solute in the extracellular compartment and the major component of serum osmolality. In normal persons in the steady state, sodium homeostasis is achieved by a balance between the dietary intake and the urinary output of sodium, whereas in intermittent hemodialysis patients, sodium balance depends on dietary intake and sodium removal during hemodialysis. Thus, the main goal of hemodialysis is to remove precisely the amount of sodium that has accumulated during the interdialytic period. Sodium removal during hemodialysis occurs via convective (~78%) and diffusive losses (~22%) between dialysate and plasma sodium concentration. The latter (the sodium gradient) is an important factor in the 'fine tuning' of sodium balance during intermittent hemodialysis. Most use fixed dialysate sodium concentrations, but each patient has his/her own plasma sodium concentrations pre-hemodialysis, which are quite reproducible and stable in the long-term. Thus, in many patients, a fixed dialysate sodium concentration will cause a persistent positive sodium balance during dialysis, which could possibly cause increased thirst, interdialytic weight gain, and mortality. Several methods will be discussed to reduce positive sodium balance, including sodium alignment.

Individualized reduction in dialysate sodium in conventional in-center hemodialysis

Recent studies have focused on the association between dialysate sodium (Na(+)) prescriptions and interdialytic weight gain (IDWG). We report on a case series of 13 patients undergoing conventional, thrice-weekly in-center hemodialysis with an individualized dialysate Na(+) prescription. Individualized dialysate Na(+) was achieved in all patients through a stepwise weekly reduction of the standard dialysate Na(+) prescription (140 mEq/L) by 2-3 mEq/L until reaching a Na(+) gradient of -2 mEq/L (dialysate Na(+) minus average plasma Na(+) over the preceding 3 months). Interdialytic weight gain, with and without indexing to dry weight (IDWG%), blood pressure, and the proportion of treatments with cramps, intradialytic hypotension (drop in systolic blood pressure >30 mmHg) and intradialytic hypotension requiring an intervention were reviewed. At the beginning of the observation period, the pre-hemodialysis (HD) plasma Na(+) concentration ranged from 130 to 141 mEq/L. When switched from the standard to the individualized dialysate Na(+) concentration, IDWG% decreased from 3.4% ± 1.6% to 2.5% ± 1.0% (P = 0.003) with no change in pre- or post-HD systolic or diastolic blood pressures (all P > 0.05). We found no significant change in the proportion of treatments with cramps (6% vs. 13%), intradialytic hypotension (62% vs. 65%), or intradialytic hypotension requiring an intervention (29% vs. 33%). Individualized reduction of dialysate Na(+) reduces IDWG% without significantly increasing the frequency of cramps or hypotension.

Dialysate sodium concentration and the association with interdialytic weight gain, hospitalization, and mortality

BACKGROUND AND OBJECTIVES

Recommendations to decrease the dialysate sodium (DNa) prescription demand analyses of patient outcomes. We analyzed morbidity and mortality at various levels of DNa, simultaneously accounting for interdialytic weight gain (IDWG) and for the mortality risk associated with lower predialysis serum sodium (SNa) levels.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We used multiply-adjusted linear mixed models to evaluate the magnitude of IDWG and Cox proportional hazards models to assess hospitalizations and deaths in 29,593 patients from the Dialysis Outcomes and Practice Patterns Study with baseline DNa and SNa as predictors, categorized according to lowest to highest levels.

RESULTS

IDWG increased with higher DNa across all SNa categories, by 0.17% of body weight per 2 mEq/L higher DNa; however, higher DNa was not associated with higher mortality in a fully adjusted model (also adjusted for SNa; hazard ratio [HR]=0.98 per 2 mEq/L higher DNa, 95% confidence interval [CI] 0.95-1.02). Instead, higher DNa was associated with lower hospitalization risk (HR=0.97 per 2 mEq/L higher DNa, 95% CI 0.95-1.00, P=0.04). Additional adjustments for IDWG did not change these results. In sensitivity analyses restricted to study facilities, in which 90%-100% of patients have the same DNa (56%), the adjusted HR for mortality was 0.88 per 2 mEq/L higher DNa (95% CI 0.83-0.94). These analyses represented a pseudo-randomized experiment in which the association between DNa and mortality is unlikely to have been confounded by indication.

CONCLUSIONS

In the absence of randomized prospective studies, the benefit of reducing IDWG by decreasing DNa prescriptions should be carefully weighed against an increased risk for adverse outcomes.

Effect of lowering dialysate sodium concentration on interdialytic weight gain and blood pressure in patients undergoing thrice-weekly in-center nocturnal hemodialysis: a quality improvement study

BACKGROUND

Patients on in-center nocturnal hemodialysis therapy typically experience higher interdialytic weight gain (IDWG) than patients on conventional hemodialysis therapy. We determined the safety and effects of decreasing dialysate sodium concentration on IDWG and blood pressure in patients on thrice-weekly in-center nocturnal hemodialysis therapy.

STUDY DESIGN

Quality improvement, pre-post intervention.

SETTINGS & PARTICIPANTS

15 participants in a single facility.

QUALITY IMPROVEMENT PLAN

Participants underwent three 12-week treatment phases, each with different dialysate sodium concentrations, as follows: phase A, 140 mEq/L; phase B, 136 or 134 mEq/L; and phase A(+), 140 mEq/L. Participants were blinded to the exact timing of the intervention.

OUTCOMES

IDWG, IDWG/dry weight (IDWG%), and blood pressure.

MEASUREMENTS

Outcome data were obtained during the last 2 weeks of each phase and compared with mixed models. The fraction of sessions with adverse events (eg, cramping and hypotension) also was reported.

RESULTS

IDWG, IDWG%, and predialysis systolic blood pressure decreased significantly by 0.6 ± 0.6 kg, 0.6% ± 0.8%, and 8.3 ± 14.9 mm Hg, respectively, in phase B compared with phase A (P < 0.05 for all comparisons). No differences in predialysis diastolic and mean arterial or postdialysis blood pressures were found (P > 0.05 for all comparisons). The proportion of treatments with intradialytic hypotension was low and similar in each phase (P = 0.9). In phase B compared with phase A, predialysis plasma sodium concentration was unchanged (P > 0.05), whereas postdialysis plasma sodium concentration decreased by 3.7 ± 1.9 mEq/L (P < 0.05).

LIMITATIONS

Modest sample size.

CONCLUSION

Decreasing dialysate sodium concentrations in patients undergoing thrice-weekly in-center nocturnal hemodialysis resulted in a clinical and statistically significant decrease in IDWG, IDWG%, postdialysis plasma sodium concentration, and predialysis systolic blood pressure without increasing adverse events. Prolonged exposure to higher than required dialysate sodium concentrations may drive IDWG and counteract some of the purported benefits of "go-slow" (longer session length) hemodialysis.

Interdialytic weight gain and ultrafiltration rate in hemodialysis: lessons about fluid adherence from a national registry of clinical practice

Excessive interdialytic weight gain (IWG) and ultrafiltration rates (UFR) above 10 mL/h/kg body weight imply higher morbidity and mortality. This study aimed to estimate the prevalence of high fluid consumers, describe UFR patterns, and describe patient characteristics associated with IWG and UFR. The Swedish Dialysis DataBase and The Swedish Renal Registry of Active Treatment of Uremia were used as data sources. Data were analyzed from patients aged >/=18 on regular treatment with hemodialysis (HD) and registered during 2002 to 2006. Interdialytic weight gain and dialytic UFR were examined in annual cohorts and the records were based on 9693 HD sessions in 4498 patients. Differences in proportions were analyzed with the chi-square test and differences in means were tested using the ANOVA or the t test. About 30% of the patients had IWG that exceed 3.5% of dry body weight and 5% had IWG >/=5.7%. The volume removed during HD was >10 mL/h/kg for 15% to 23% of the patients, and this rate increased during the first dialytic year. Patient characteristics associated with fluid overload were younger age, lower body mass index, longer dialytic vintage, and high blood pressure. By studying IWG and dialytic UFR as quality indicators, it is shown that there is a potential for continuing improvement in the care of patients in HD settings, i.e., to enhanced adherence to fluid restriction or alternatively to extend the frequency of dialysis for all patients, e.g., by providing daily treatment.