Dialysis parameters associated with SARS-CoV-2 infection and prognosis in end-stage kidney disease

BACKGROUND

The Covid-19 pandemic has affected patients with end-stage kidney disease (ESKD). Whether dialysis parameters have a prognostic value in ESKD patients with Covid-19 remains unclear.

MATERIALS AND METHODS

We retrospectively evaluated clinical characteristics, blood pressure (BP) and dialysis parameters in ESKD patients undergoing maintenance outpatient hemodialysis, with (Covid-ESKD) and without (No-Covid-ESKD) Covid-19, at four Brazilian hemodialysis facilities. The Covid-ESKD (n = 107; 54% females; 60.8 ± 17.7 years) and No-Covid-ESKD (n = 107; 62% females; 58.4 ± 14.6 years) groups were matched by calendar time. The average BP and dialysis parameters were calculated during the pre-infection, acute infection, and post-infection periods. The main outcomes were Covid-19 hospitalization and all-cause mortality.

RESULTS

Covid-ESKD patients had greater intradialytic and postdialysis systolic BP and lower predialysis weight, postdialysis weight, ultrafiltration rate, and interdialytic weight gain during acute-illness compared to 1-week-before-illness, while these changes were not observed in No-Covid-ESKD patients. After 286 days of follow-up (range, 276-591), there were 18 Covid-19-related hospitalizations and 28 deaths among Covid-ESKD patients. Multivariable logistic regression analysis showed that increases in predialysis systolic BP from 1-week-before-illness to acute-illness (OR, 95%CI = 1.06, 1.02-1.10; p = .004) and Covid-19 vaccination (OR, 95%CI = 0.16, 0.04-0.69; p = .014) were associated with hospitalization in Covid-ESKD patients. Multivariable Cox-regression analysis showed that Covid-19-related hospitalization (HR, 95%CI = 5.17, 2.07-12.96; p < .001) and age (HR, 95%CI = 1.05, 1.01-1.08; p = .008) were independent predictors of all-cause mortality in Covid-ESKD patients.

CONCLUSION

Acute Covid-19 illness is associated with variations in dialysis parameters of volume status in patients with ESKD. Furthermore, increases in predialysis BP during acute Covid-19 illness are associated with an adverse prognosis in Covid-ESKD patients.

The value of bioimpedance analysis in the assessment of hydration and nutritional status in children on chronic peritoneal dialysis

Bioimpedance analysis (BIA)-body composition monitoring (BCM) has been used to evaluate the hydration and nutritional status of adults and children on dialysis. However, its clinical application still has challenges, so further exploration is valuable. We used BIA-BCM to evaluate the hydration and nutritional status of children undergoing chronic peritoneal dialysis from 1 July 2021 to 31 December 2022 in the Children's Hospital of Fudan University to explore the clinical value of this method. A total of 84 children on chronic peritoneal dialysis (PD) were included. In the PD group, 16 (19.05%) and 31 (36.90%) had mild and severe overhydration (OH), respectively; 41.27% (26/63) had a low lean tissue index (LTI). In the PD group, patients with relative OH (Re-OH) > 5.6% had significantly higher systolic blood pressure (SBP) and SBP z score (SBPz). Patients with LTI > 12% had significantly higher body mass index (BMI) and BMI z score (BMIz). Canonical correlation analysis indicated a linear relationship (ρ = 0.708) between BIA-BCM hydration and the clinical hydration indicator and a linear relationship (ρ = 0.995) between the BIA-BCM nutritional indicator and the clinical nutritional indicator. A total of 56% of children on chronic peritoneal dialysis had OH, and 41% had a low LTI. In PD patients, SBP and SBPz were correlated with BIA-BCM Re-OH, and BMI and BMIz were correlated with BIA-BCM LTI. BIA-BCM indicators have good clinical value in evaluating hydration and nutrition.

Association of Bioimpedance Parameters with Increases in Blood Pressure during Hemodialysis

BACKGROUND

Intradialytic hypertension, defined as an increase in BP from pre- to post-hemodialysis (HD), affects 5%-15% of patients receiving maintenance HD and is associated with cardiovascular and all-cause mortality. Hypervolemia is believed to be a major etiological factor, yet the association of more objective biomarkers of volume status with intradialytic hypertension is not well described.

METHODS

In a post hoc analysis of the Frequent Hemodialysis Network Daily Trial ( n =234), using data from baseline, 1-, 4-, and 12-month visits ( n =800), we used random-effects regression to assess the association of bioimpedance estimates of volume (vector length) with post-HD systolic BP (continuous) and any increase in systolic BP (categorical) from pre- to post-HD. We adjusted models for randomized group; age; sex; self-reported race; Quételet (body mass) index; vascular access; HD vintage; hypertension; history of heart failure; diabetes; residual kidney function (urea clearance); pre-HD systolic BP; ultrafiltration rate; serum-dialysate sodium gradient; and baseline values of hemoglobin, phosphate, and equilibrated Kt/V urea.

RESULTS

The mean age of participants was 50±14 years, 39% were female, and 43% were Black. In adjusted models, shorter vector length (per 50 Ω/m) was associated with higher post-HD systolic BP (2.9 mm Hg; 95% confidence interval [CI], 1.6 to 4.3) and higher odds of intradialytic hypertension (odds ratio 1.66; 95% CI, 1.07 to 2.55). Similar patterns of association were noted with a more stringent definition of intradialytic hypertension (>10 mm Hg increase from pre- to post-HD systolic BP), where shorter vector length (per 50 Ω/m) was associated with a higher odds of intradialytic hypertension (odds ratio 2.17; 95% CI, 0.88 to 5.36).

CONCLUSIONS

Shorter vector length, a bioimpedance-derived proxy of hypervolemia, was independently associated with higher post-HD systolic BP and risk of intradialytic hypertension.

The severity of early fluid overload assessed by bioelectrical vector impedance as an independent risk factor for longer patient care after cardiac surgery

BACKGROUND AND AIMS

Fluid overload is a common postoperative complication in patients undergoing cardiac surgery. Although this condition is notably associated with relevant adverse outcomes, assessment of hydration status in clinical practice is challenging. Bioelectrical impedance vector analysis (BIVA) has emerged as a potentially effective method to monitor hydration changes, but the available evidence in critically ill patients undergoing cardiac surgery is limited and sometimes conflicting. The aim of this study was to explore by mean of BIVA the evolution over time of hydration status and its impact on relevant outcomes.

METHODS

Prospective observational study enrolling 130 patients undergoing cardiac surgery. Height normalized impedance was calculated both before surgery (baseline) and in the first five postoperative days. Relevant clinical and laboratory data were collected daily close to BIVA measurements. Length of mechanical ventilation (MV), intensive care unit (ICU) and hospital stay exceeding the 75th percentile of the study population were considered as study endpoints.

RESULTS

Compared to baseline, a significant reduction in impedance was found at first postoperative day, demonstrating a relevant fluid overload. An adjusted impedance at first postoperative day shorter than the best respective threshold was associated to longer MV (7.4 times), ICU stay (4.7 times) and hospital stay (5.6 times). A significant change in impedance and phase angle was documented throughout the observation days (p < 0.001), without returning to the baseline value. The co-existence of low impedance and high plasma osmolarity increased significantly the risk of incurring the study outcomes.

CONCLUSIONS

In patients with cardiac surgery-induced fluid overload, recovery to baseline conditions occurs slowly. A relevant early fluid overload should be considered predictive for longer time of MV, ICU and total hospital stay.

Effects of Empagliflozin on Fluid Overload, Weight, and Blood Pressure in CKD

SIGNIFICANCE STATEMENT

SGLT2 inhibitors reduce risk of kidney progression, AKI, and cardiovascular disease, but the mechanisms of benefit are incompletely understood. Bioimpedance spectroscopy can estimate body water and fat mass. One quarter of the EMPA-KIDNEY bioimpedance substudy CKD population had clinically significant levels of bioimpedance-derived "Fluid Overload" at recruitment. Empagliflozin induced a prompt and sustained reduction in "Fluid Overload," irrespective of sex, diabetes, and baseline N-terminal pro B-type natriuretic peptide or eGFR. No significant effect on bioimpedance-derived fat mass was observed. The effects of SGLT2 inhibitors on body water may be one of the contributing mechanisms by which they mediate effects on cardiovascular risk.

BACKGROUND

CKD is associated with fluid excess that can be estimated by bioimpedance spectroscopy. We aimed to assess effects of sodium glucose co-transporter 2 inhibition on bioimpedance-derived "Fluid Overload" and adiposity in a CKD population.

METHODS

EMPA-KIDNEY was a double-blind placebo-controlled trial of empagliflozin 10 mg once daily in patients with CKD at risk of progression. In a substudy, bioimpedance measurements were added to the main trial procedures at randomization and at 2- and 18-month follow-up visits. The substudy's primary outcome was the study-average difference in absolute "Fluid Overload" (an estimate of excess extracellular water) analyzed using a mixed model repeated measures approach.

RESULTS

The 660 substudy participants were broadly representative of the 6609-participant trial population. Substudy mean baseline absolute "Fluid Overload" was 0.4±1.7 L. Compared with placebo, the overall mean absolute "Fluid Overload" difference among those allocated empagliflozin was -0.24 L (95% confidence interval [CI], -0.38 to -0.11), with similar sized differences at 2 and 18 months, and in prespecified subgroups. Total body water differences comprised between-group differences in extracellular water of -0.49 L (95% CI, -0.69 to -0.30, including the -0.24 L "Fluid Overload" difference) and a -0.30 L (95% CI, -0.57 to -0.03) difference in intracellular water. There was no significant effect of empagliflozin on bioimpedance-derived adipose tissue mass (-0.28 kg [95% CI, -1.41 to 0.85]). The between-group difference in weight was -0.7 kg (95% CI, -1.3 to -0.1).

CONCLUSIONS

In a broad range of patients with CKD, empagliflozin resulted in a sustained reduction in a bioimpedance-derived estimate of fluid overload, with no statistically significant effect on fat mass.

TRIAL REGISTRATION

Clinicaltrials.gov: NCT03594110 ; EuDRACT: 2017-002971-24 ( https://eudract.ema.europa.eu/ ).

The moderating effect of fluid overload on the relationship between the augmentation index and left ventricular diastolic function in patients with CKD

Increased vascular stiffness, fluid overload, and left ventricular diastolic dysfunction (LVDD) are common in patients with chronic kidney disease (CKD). We investigated the potential moderating effect of volume status in the relationship between arterial stiffness and left ventricular (LV) diastolic function in non-dialysis patients with stage 5 CKD. The radial augmentation index at a heart rate of 75 beats/min (rAIx75), overhydration/extracellular water (OH/ECW), and E/e´ ratio were concurrently measured in 152 consecutive patients. Each of these parameters reflects the status of vascular stiffness, fluid balance, and LV diastolic function, respectively. Hierarchical regression analysis demonstrated a significant interaction effect of OH/ECW for all patients (P = 0.015), even after controlling for confounders. In separate analyses, this interaction effect was particularly significant in women (P = 0.010), whereas its significance in patients with diabetes was marginally significant (P = 0.062). Our study suggested that fluid overload could be one of the more aggravating factors of LVDD in patients with CKD who have increased arterial stiffness. Therefore, it is advisable to conduct simultaneous assessments of vascular stiffness, fluid balance, and LV function, particularly in the specific groups mentioned earlier. Our results may serve as evidence applicable to patients with chronic heart failure.

Nutritional Assessments by Bioimpedance Technique in Dialysis Patients

Bioelectrical impedance analysis (BIA) has been extensively applied in nutritional assessments on the general population, and it is recommended in establishing the diagnosis of malnutrition and sarcopenia. The bioimpedance technique has become a promising modality through which to measure the whole-body composition in dialysis patients, where the presence of subclinical volume overload and sarcopenic obesity may be overlooked by assessing body weight alone. In the past two decades, bioimpedance devices have evolved from applying a single frequency to a range of frequencies (bioimpedance spectroscopy, BIS), in which the latter is incorporated with a three-compartment model that allows for the simultaneous measurement of the volume of overhydration, adipose tissue mass (ATM), and lean tissue mass (LTM). However, clinicians should be aware of common potential limitations, such as the adoption of population-specific prediction equations in some BIA devices. Inherent prediction error does exist in the bioimpedance technique, but the extent to which this error becomes clinically significant remains to be determined. Importantly, reduction in LTM has been associated with increased risk of frailty, hospitalization, and mortality in dialysis patients, whereas the prognostic value of ATM remains debatable. Further studies are needed to determine whether modifications of bioimpedance-derived body composition parameters through nutrition intervention can result in clinical benefits.

Comparison of whole body versus thoracic bioimpedance in relation to ultrafiltration volume and systolic blood pressure during hemodialysis

In contrast to whole body bioimpedance, which estimates fluid status at a single point in time, thoracic bioimpedance applied by a wearable device could enable continuous measurements. However, clinical experience with thoracic bioimpedance in patients on dialysis is limited. To test the reproducibility of whole body and thoracic bioimpedance measurements and to compare their relationship with hemodynamic changes during hemodialysis, these parameters were measured pre- and end-dialysis in 54 patients during two sessions. The resistance from both bioimpedance techniques was moderately reproducible between two dialysis sessions (intraclass correlations of pre- to end-dialysis whole body and thoracic resistance between session 1 and 2 were 0.711 [0.58-0.8] and 0.723 [0.6-0.81], respectively). There was a very high to high correlation between changes in ultrafiltration volume and changes in whole body thoracic resistance. Changes in systolic blood pressure negatively correlated to both bioimpedance techniques. Although the relationship between changes in ultrafiltration volume and changes in resistance was stronger for whole body bioimpedance, the relationship with changes in blood pressure was at least comparable for thoracic measurements. These results suggest that thoracic bioimpedance, measured by a wearable device, may serve as an interesting alternative to whole body measurements for continuous hemodynamic monitoring during hemodialysis.NEW & NOTEWORTHY We examined the role of whole body and thoracic bioimpedance in hemodynamic changes during hemodialysis. Whole body and thoracic bioimpedance signals were strongly related to ultrafiltration volume and moderately, negatively, to changes in blood pressure. This work supports the further development of a wearable device measuring thoracic bioimpedance longitudinally in patients on hemodialysis. As such, it may serve as an innovative tool for continuous hemodynamic monitoring during hemodialysis in hospital or in a home-based setting.

Bioimpedanciometry in nutritional and hydration assessments in a single dialysis center

BACKGROUND

Bioimpedance analysis (BIA) has been demonstrated to add accuracy to nutritional and volume status assessments in dialysis (HD) patients.

AIM

to describe a sample of dialysis patients from a single center on their demographics and BIA of volume distribution and nutritional status, and mortality during 12-month follow-up.

METHODS

prospective observational cohort study to evaluate vintage HD patients with single-frequency BIA.

RESULTS

we evaluated 82 patients, 29% over 65 years old. Elderly patients had higher ECW/TBW (0.51 vs. 0.44, p < 0.0001), and narrower phase angle (PhA) (4.9 vs. 6.4º, p < 0.0001). Fifteen patients (18.2%) died during follow-up, eight (53%) were elderly. Death was associated with age (62.6 vs. 50.2 years, p = 0.012), post-HD PhA (4.8 vs. 6.2º, p = 0.0001), and post-HD ECW/TBW (0.50 vs. 0.45, p = 0.015). The ROC curve analysis to predict mortality found ECW/TBW ≥ 0.47 and PhA ≤ 5.5º to have the best sensitivity and specificity. One-year patient survival was lower with post-HD ECW/TBW ≥ 0.47 (69.5% vs. 90.6%, p = 0.019), age ≥ 65 years (64.2%, vs. 86.2%, p = 0.029), and PhA ≤ 5.5º (68.2 vs. 91.0%, p = 0.002). Cox regression analysis demonstrated that PhA [HR 5.04 (95%CI 1.60-15.86), p = 0.006] remained associated with death after adjusting for age and ECW/TBW.

CONCLUSION

BIA is useful in assessing volume distribution and nutrition in HD patients, and combined with clinical judgement, may help determine dry weight, especially in elderly patients. Narrower PhA and higher ECW/TBW after HD were associated with poorer one-year survival.

Bioimpedanciometria em avaliações nutricionais e de hidratação em um único centro de diálise

RESUMO Antecedentes: Análise de bioimpedância (BIA) demonstrou adicionar acurácia às avaliações de estado nutricional e de volume em pacientes em diálise (HD). Objetivo: descrever amostra de pacientes em diálise de um único centro quanto aos aspectos demográficos e BIA na distribuição de volume e no estado nutricional, e a mortalidade em 12 meses de acompanhamento. Métodos: estudo de coorte observacional prospectivo para avaliar pacientes prevalentes em HD com BIA de frequência única. Resultados: avaliamos 82 pacientes, 29% acima de 65 anos. Pacientes idosos apresentaram maior AEC/ACT (0,51 vs. 0,44; p < 0,0001), e ângulo de fase mais estreito (PhA) (4,9 vs. 6,4º; p < 0,0001). Quinze pacientes (18,2%) foram a óbito durante acompanhamento, oito (53%) eram idosos. Óbito foi associado à idade (62,6 vs. 50,2 anos, p = 0,012), PhA pós-HD (4,8 vs. 6,2º; p = 0,0001), e AEC/ACT pós-HD (0,50 vs. 0,45, p = 0,015). A análise da curva ROC para prever mortalidade constatou que AEC/ACT ≥ 0,47 e PhA ≤ 5,5º apresentam melhor sensibilidade e especificidade. Sobrevida do paciente em um ano foi menor com AEC/ACT pós-HD ≥ 0,47 (69,5% vs. 90,6%; p = 0,019), idade ≥ 65 anos (64,2% vs. 86,2%; p = 0,029), e PhA ≤ 5,5º (68,2 vs. 91,0%; p = 0,002). A análise de regressão de Cox demonstrou que PhA [HR 5,04 (IC 95% 1,60–15,86); p = 0,006] permaneceu associado ao óbito após ajuste para idade e AEC/ACT. Conclusão: BIA é útil ao avaliar distribuição de volume e nutrição em pacientes em HD, e juntamente com julgamento clínico, pode ajudar a determinar o peso seco, principalmente em pacientes idosos. PhA mais estreito e maior AEC/ACT pós-HD foram associados a pior sobrevida em um ano.

Portable sauna stimulated-diaphoresis for the treatment of fluid-overload in peritoneal dialysis patients: A pilot study

Background

Fluid overload (FO) is a common problem in patients with peritoneal dialysis (PD), it is associated with adverse outcomes and may persist despite adjustements in PD therapy.

Objective

To evaluate the feasibility and safety of stimulated diaphoresis to reduce FO with the use of a portable sauna bath.

Methods

Open-label pilot study in patients on continuous ambulatory peritoneal dialysis (CAPD) and FO. The primary outcome was the treatment-related adverse events; secondary outcomes were changes in over-hydration (OH), body weight and blood pressure, FO symptoms, and sleep quality. Dialysis prescription and daily data were recorded. The intervention period consisted in a 30-min, 45°C sauna bath, daily for 10 days, using a portable sauna bath.

Results

Fifty-one out of 54 total sauna bath sessions were well tolerated. In three (5.5%) sessions adverse effects were reported: transient dizziness in two cases, and a second-degree skin burn in a patient with advanced diabetic neuropathy. OH (6.3 ± 1.2 L vs. 5.5 ± 1.3 L, p = 0.05), body weight (67.7 ± 11.4 vs. 66.8 ± 3.8 kg, p = 0.003), diastolic blood pressure (92 ± 13.5 vs. 83 ± 13.3 mmHg, P = 0.003) and PSQI score (7.3 ± 3.7 vs. 5.1 ± 3.2, p = 0.02) improved significantly between the control and intervention period, respectively.

Conclusions

Stimulated diaphoresis with a portable sauna bath could be a novel, safe, and effective alternative way to reduce FO in CAPD patients. Larger studies are needed to confirm our results.

Clinical trial registration

ClinicalTrials.gov, identifier: NCT03563898.

Multifrequency bioimpedance by spectroscopy vs. routine methods in the management of hydration status in peritoneal dialysis patients: A randomized control trial

Background

Overhydration (OH) is common in peritoneal dialysis (PD) and increases the cardiovascular risk. Multifrequency bioimpedance spectroscopy (BIS) has been proposed to estimate the hydration in dialysis. Our objective was to evaluate if BIS is superior than control based on clinical assessment plus single-frequency bioimpedance (SF-BIA) on the fluid control and intermediate cardiovascular outcomes.

Methods

Randomized controlled study in adult PD patients, with a 9-month follow-up, allocated into two groups: control and BIS. Data were collected from medical records. SF-BIA and BIS, laboratory exams, ambulatory blood pressure monitoring, echocardiography (ECHO), and pulse wave velocity (PWV) were evaluated. The BIS data were available to the medical team only in BIS group.

Results

34 patients completed the study, 17 in each group. At the endpoint the BIS group had a significant (p < 0.05) greater proportion of patients with OH/extracellular water (OH/ECW%) ≤ 15% than the control (94.1% vs. 52.9%), and a lower OH mean (2.1 ± 1.6 vs. 0.9 ± 1.1 L). The control group has a significant increase in the tumor necrosis factor alpha median concentration from baseline to six [11.9 (6.0–24.1) vs. 44.7 (9.4–70.6) pg/ml] and 9 months [11.9 (6.0–24.1) vs. 39.4 (27.9–62.6) pg/ml], and in the N-terminal fragment of pro-B-type natriuretic peptide median [239 (171.5–360.5) vs. 356 (219–1,555) pg/ml]. For cardiovascular parameters, BIS group presented a significant reduction in radial PWV [7.7 (6.9–9.2) vs. 6.5 (5.5–8.4) m/s] at 9 month, while in the control presented a significant increase in mean central systolic blood pressure (BP) (106.8 ± 11.2 vs. 117.6 ± 16.5 mmHg) and in central diastolic BP (90.4 ± 9.8 vs. 103.3 ± 12.5 mmHg) at 9 months. The left ventricular mass (LVM)/body surface presented a significant reduction in the control (109.6 ± 30.8 vs. 101.2 ± 28.9 g/m²) and BIS group (107.7 ± 24.9 vs. 96.1 ± 27.0 g/m²) at 9 months.

Conclusion

The results suggest BIS is superior than the clinical evaluation plus SF-BIA for the fluid control of PD patients.

Clinical trial registration

[https://www.ClinicalTrials.gov], identifier [RBR-10k8j3bx].

Bioimpedance indices of fluid overload and cardiorenal outcomes in heart failure and chronic kidney disease: a systematic review

BACKGROUND

Bioimpedance-based estimates of fluid overload have been widely studied and systematically reviewed in dialysis populations, but data from heart failure or non-dialysis chronic kidney disease (CKD) populations have not.

METHODS AND RESULTS

We conducted a systematic review of studies using whole-body bioimpedance from heart failure and non-dialysis CKD populations which reported associations with mortality, cardiovascular outcomes and/or CKD progression. We searched MEDLINE, Embase databases and the Cochrane CENTRAL registry from inception to 14^th March 2022. Thirty one eligible studies were identified: 20 heart failure and 11 CKD cohorts, with 2 studies including over 1000 participants. A wide range of different bioimpedance methods were used across the studies (heart failure: 8 parameters; CKD: 6). Studies generally reported positive associations, but between-study differences in bioimpedance methods, fluid overload exposure definitions, and modelling approaches precluded meta-analysis. The largest identified study was in non-dialysis CKD (Chronic Renal Insufficiency Cohort, 3751 participants) which reported adjusted hazard ratios (95% confidence intervals) for phase angle <5.59 versus ≥6.4 of 2.02 (1.67-2.43) for all-cause mortality; 1.80 (1.46-2.23) for heart failure events; and 1.78 (1.56-2.04) for CKD progression.

CONCLUSIONS

Bioimpedance indices of fluid overload are associated with risk of important cardiorenal outcomes in heart failure and CKD. Facilitation of more widespread use of bioimpedance needs consensus on the optimum device, standardized analytical methods, and larger studies including more detailed characterization of cardiac and renal phenotypes.

Concordance between bio-impedance analysis and clinical score in fluid-status assessment of maintenance haemodialysis patients: A single centre experience

BACKGROUND

The burden of chronic kidney disease (CKD) is rising rapidly globally. Fluid overload (FO), an independent predictor of mortality in CKD, should be accurately assessed to guide estimation of the volume of fluid to be removed during haemodialysis (HD). Clinical score (CS) and bio-impedance analysis (BIA) have been utilized in assessment of FO and BIA has demonstrated reproducibility and accuracy in determination of fluid status in patients on HD. There is need to determine the performance of locally-developed CSs in fluid status assessment when evaluated against BIA.

AIM

To assess the hydration status of patients on maintenance HD using BIA and a CS, as well as to evaluate the performance of that CS against BIA in fluid status assessment.

METHODS

This was a single-centre, hospital-based cross-sectional study which recruited adult patients with CKD who were on maintenance HD at Kenyatta National Hospital. The patients were aged 18 years and above and had been on maintenance HD for at least 3 mo. Those with pacemakers, metallic implants, or bilateral limbs amputations were excluded. Data on the patients’ clinical history, physical examination, and chest radiograph findings were collected. BIA was performed on each of the study participants using the Quantum^® II bio-impedance analyser manufactured by RJL Systems together with the BC 4^® software. In evaluating the performance of the CS, BIA was considered as the gold standard test. A 2-by-2 table of the participants’ fluid status at each of the CS values obtained compared to their paired BIA results was constructed (either ++, +-, -- or -+ for FO using the CS and BIA, respectively). The results from this 2-by-2 table were used to compute the sensitivity and specificity of the CS at the various reference points and subsequently plot a receiver operating characteristic (ROC) curve that was used to determine the best cut-off point. Those above and below the best CS cut-off point as determined by the ROC were classified as being positive and negative for FO, respectively. The proportions of participants diagnosed with FO by the CS and BIA, respectively, were computed and summarized in a 2-by-2 contingency table for comparison. McNemar’s chi-squared test was used to assess any statistically significant difference in proportions of patients diagnosed as having FO by CS and BIA. Logistic regression analysis was conducted to assess whether the variables for the duration of dialysis, the number of missed dialysis sessions, advisement by health care professional on fluid or salt intake, actual fluid intake, the number of anti-hypertensives used, or body mass index were associated with a patient’s odds of having FO as diagnosed by BIA.

RESULTS

From 100 patients on maintenance HD screened for eligibility, 80 were recruited into this study. Seventy-one (88.75%) patients were fluid overloaded when evaluated using BIA with mean extracellular volume of 3.02 ± 1.79 L as opposed to the forty-seven (58.25%) patients who had FO when evaluated using the CS. The difference was significant, with a P value of < 0.0001 (95% confidence interval: 0.1758-0.4242). Using CS, values above 4 were indicative of FO while values less than or equal to 4 denoted the best cut-off for no FO. The sensitivity and specificity for the CS were 63% and 78% respectively. None of the factors evaluated for association with FO showed statistical significance on the multivariable logistic regression model.

CONCLUSION

FO is very prevalent in patients on chronic HD at the Kenyatta National Hospital. CS detects FO less frequently when compared with BIA. The sensitivity and specificity for the CS were 63% and 78% respectively. None of the factors evaluated for association with FO showed statistical significance on the multivariable logistic regression model.

Identification of fluid overload in elderly CKD Patients using bioimpedance techniques

Diagnosis of fluid overload (FO) in early stage is essential to manage chronic kidney disease (CKD) patients' fluid balance and to prevent cardiovascular disease (CVD). However, identification of fluid status in CKD patient is largely dependent on physician's clinical acumen. The ratio of fluid overload to extracellular volume (FO/ECV) has been used as a reference to assess fluid status. The primary aim of this study was to compare FO/ECV with other bioimpedance methods and clinical assessment in CKD patients. Whole body ECV, intracellular volume (ICV), total body water (TBW) and calf normalized resistivity (CNR) were measured (Hydra 4200). Thresholds of FO utilizing CNR and ECV/TBW were derived by receiver operator characteristic (ROC) analysis based on data from pooled CKD patients and healthy subjects (HS). Clinical assessments of FO in CKD patients were performed by nephrologists . CKD (stage 3 and stage 4) patients (n=50) and HS (n=189) were studied. The thresholds of FO were ≤ 14.3 (10^-2 Ωm³/kg) for females and ≤ 13.1 (10^-2 Ωm³/kg) for males using CNR and ≥ 0.445 in females and ≥ 0.434 in males using ECV/TBW. FO was diagnosed in 78%, 62% and 52% of CKD patients by CNR, FO/ECV and ECV/TBW, respectively while only 24% of CKD patients were diagnosed to be FO by clinical assessment . The proportion of FO in non-dialysis CKD patients was largely underestimated by clinical assessment compared to FO/ECV, CNR and ECV/TBW. CNR, and FO/ECV methods were more sensitive than ECV/TBW in identifying fluid overload in these CKD patients.

Inter- and intradialytic fluid volume changes and vascular stiffness parameters in patients on hemodialysis

BACKGROUND

Whether fluid overload is associated with vascular stiffness parameters in hemodialysis (HD) patients has not been fully elucidated. We hypothesized that interdialytic fluid accumulation increases vascular stiffness parameters, which improves with intradialytic ultrafiltration.

METHODS

Fluid overload and vascular stiffness parameters were assessed in 39 HD patients (20 with and 19 without fluid overload) and compared to 26 healthy controls. Fluid status was assessed 15 minutes before the mid-week HD session by bio-impedance spectroscopy. Following this, ambulatory pulse wave velocity (PWV) and augmentation index (AIx) were measured for 24 hours before another mid-week HD session and then for 5 hours starting 30 minutes before and ending 30 minutes after the session.

RESULTS

HD patients had significant fluid overload compared to healthy controls (2.0±2.4 vs. -0.2±0.6 L; P<0.001) and baseline PWV was higher (10.3±1.7 vs. 8.8±1.4 m/s; P<0.001). There was no significant difference between PWV and AIx in fluid overloaded and non-fluid overloaded HD patients prior to, or during the HD session. AIx of non-fluid overloaded HD patients improved after the HD session (P = 0.04). Average 24-hour AIx was higher in fluid overloaded HD patients (P<0.001).

CONCLUSIONS

Inter- and intradialytic changes in fluid volume were only weakly related to vascular stiffness parameters in HD patients. Although there was a modest reduction in AIx in non-fluid overloaded HD patients after the dialysis session, fluid removal did not improve vascular stiffness parameters during the HD session. We speculate that the effect of fluid overload correction on vascular stiffness parameters requires long-term adjustments in the vasculature.

Protocol of a pilot-scale, single-arm, observational study to assess the utility and acceptability of a wearable hydration monitor in haemodialysis patients

Background

Fluid overload has a high prevalence in haemodialysis patients and is an important risk factor for excess mortality and hospitalisations. Despite the risks associated with chronic fluid overload, it is clinically difficult to assess and maintain fluid status adequately. Current methods of fluid status assessment are either imprecise or time intensive. In particular, to date, no method exists to accurately assess fluid status during the interdialytic interval.

Objectives

This pilot study aimed to evaluate whether a prototype wearable hydration monitor can accurately and reproducibly detect fluid overload in the haemodialysis population when compared to haemodialysis and bioimpedance data.

Methods

A prospective, open-label, single-arm observational trial of 20 patients commenced in January 2021 in a single haemodialysis centre in Ireland, with a wearable hydration monitor, the Sixty device. The Sixty device uses diffuse reflectance spectroscopy to measure fluid levels at the level of the subdermis and uses machine learning to develop an algorithm that can determine fluid status. The Sixty device was worn at every dialysis session and nocturnally over a three-week observational period. Haemodialysis parameters including interdialytic weight gain, ultrafiltration volume, blood pressure, and relative blood volume were collected from each session, and bioimpedance measurements using the Fresenius body composition monitor were performed on 4 occasions as a comparator. The primary objective of this trial was to determine the accuracy and reproducibility of the Sixty device compared to bioimpedance measurements.

Conclusion

If the accuracy of the wearable hydration monitor is validated, further studies will be conducted to integrate the device output into a multi-parameter machine learning algorithm that can provide patients with actionable insights to manage fluid overload in the interdialytic period.

Trial registration

www.clinicaltrials.govNCT04623281. Registered November 10th, 2020.

Serum Growth Differentiation Factor-15/Albumin Ratio as a 2-Year Survival Marker of End-Stage Renal Disease Patients Initiating Maintenance Hemodialysis

It is important to identify risk factors related to mortality in end-stage renal disease (ESRD) patients starting renal replacement therapy. Recently, several studies proposed that growth-differentiation factor-15 (GDF-15) is a possible biomarker for the prognosis of patients on maintenance hemodialysis. Here, we investigated the predictive value of serum GDF-15/Albumin ratio on two-year mortality in ESRD patients initiating maintenance hemodialysis. The study was a single center, retrospective study on ESRD patients starting maintenance hemodialysis with a follow-up of two years. All patients completed laboratory test and bioimpedance spectroscopy prior to the initiation of the first dialysis. The patients were stratified into quartiles according to the quartiles of serum GDF-15/Albumin ratio. Among the 159 patients, the mean age was 61.78 ± 12.52 years and median survival was 20.03 ± 7.73 months. The highest GDF-15/Albumin quartile was significantly more associated with the increased risk of all-cause mortality than other quartiles (unadjusted hazard ratio (HR): 8.468, 95% CI 2.981–24.054, p < 0.001). Older age and a higher overhydration state were associated with GDF-15/Albumin ratio. The ROC analysis confirmed that the ability of the GDF-15/Albumin ratio to predict mortality was superior to GDF-15 or albumin alone. In conclusion, the GDF-15/Albumin ratio measured at the initial maintenance hemodialysis is an independent prognostic marker of two-year mortality in ESRD patients.

Association of Prescription With Body Composition and Patient Outcomes in Incident Peritoneal Dialysis Patients

Objective: The nutritional status of patients on peritoneal dialysis (PD) is influenced by patient- and disease-related factors and lifestyle. This analysis evaluated the association of PD prescription with body composition and patient outcomes in the prospective incident Initiative for Patient Outcomes in Dialysis–Peritoneal Dialysis (IPOD-PD) patient cohort.

Design and Methods: In this observational, international cohort study with longitudinal follow-up of 1,054 incident PD patients, the association of PD prescription with body composition was analyzed by using the linear mixed models, and the association of body composition with death and change to hemodialysis (HD) by means of a competing risk analysis combined with a spline analysis. Body composition was regularly assessed with the body composition monitor, a device applying bioimpedance spectroscopy.

Results: Age, time on PD, and the use of hypertonic and polyglucose solutions were significantly associated with a decrease in lean tissue index (LTI) and an increase in fat tissue index (FTI) over time. Competing risk analysis revealed a U-shaped association of body mass index (BMI) with the subdistributional hazard ratio (HR) for risk of death. High LTI was associated with a lower subdistributional HR, whereas low LTI was associated with an increased subdistributional HR when compared with the median LTI as a reference. High FTI was associated with a higher subdistributional HR when compared with the median as a reference. Subdistributional HR for risk of change to HD was not associated with any of the body composition parameters. The use of polyglucose or hypertonic PD solutions was predictive of an increased probability of change to HD, and the use of biocompatible solutions was predictive of a decreased probability of change to HD.

Conclusion: Body composition is associated with non-modifiable patient-specific and modifiable treatment-related factors. The association between lean tissue and fat tissue mass and death and change to HD in patients on PD suggests developing interventions and patient counseling to improve nutritional markers and, ultimately, patient outcomes.

Study Registration: The study has been registered at Clinicaltrials.gov (NCT01285726).

Assessment of volemia status using ultrasound examination of the inferior vena cava and spectroscopic bioimpendance in hemodialysis patients

Background/Aim. Hypervolemia is an important risk factor for the development of cardiovascular morbidity and mortality in patients treated with regular hemodialysis. There is still no reliable method for assessing the status of volemia in these patients. The aim of the study was to assess the status of volemia in patients treated with regular hemodialysis by measuring the parameters of the inferior vena cava (IVC) and bioimpedance. Methods. The effect of hemodialysis treatment on ultrasound parameters of the IVC, as well as on the parameters measured by bioimpedance, was examined before and after hemodialysis. The values of the N-terminal prohormone of brain natriuretic peptide (NT-proBNP) were measured both before and after hemodialysis. Forty-five patients were involved in this non-interventional cross-section study, including the patients treated with standard bicarbonate dialysis. According to the interdialytic yield, the patients were divided into three groups: I (up to 2,000 mL), II (2,000?3,000 mL), and III (over 3,000 mL). Results. The values of the IVC parameters and the parameters measured with bioimpedance were significantly lower after treatment with hemodialysis (p < 0.005). The third group of patients had a significantly higher total fluid volume in the body com-pared to the group I, as well as a significantly greater volume of extracellular fluid (p < 0.005). The significantly lower values of NT-proBNP in all groups (p < 0.005) were detected after hemodialysis. After treatment with hemodialysis, a positive correlation was observed between the concentration of NT-proBNP in the serum and the extracellular/intracellular water ratio. However, the correlation between NT-proBNP concentration and total fluid measured by bioimpedance spectroscopy did not reach statistical significance. Conclusion. Measurement of the IVC ultrasound parameters and volemia parameters using bioimpedance significantly contributes to the assessment of the status of volemia. Nevertheless, it cannot be used as a separate parameter, only in combination with all other methods.

OUP accepted manuscript

Patients on chronic hemodialysis are counseled to reduce dietary sodium intake to limit their thirst and consequent interdialytic weight gain (IDWG), chronic volume overload and hypertension. Low-sodium dietary trials in hemodialysis are sparse and mostly indicate that dietary education and behavioral counseling are ineffective in reducing sodium intake and IDWG. Additional nutritional restrictions and numerous barriers further complicate dietary adherence. A low-sodium diet may also reduce tissue sodium, which is positively associated with hypertension and left ventricular hypertrophy. A potential alternative or complementary approach to dietary counseling is home delivery of low-sodium meals. Low-sodium meal delivery has demonstrated benefits in patients with hypertension and congestive heart failure but has not been explored or implemented in patients undergoing hemodialysis. The objective of this review is to summarize current strategies to improve volume overload and provide a rationale for low-sodium meal delivery as a novel method to reduce volume-dependent hypertension and tissue sodium accumulation while improving quality of life and other clinical outcomes in patients undergoing hemodialysis.

Prevalence of fluid overload in an urban US hemodialysis population: A cross-sectional study

INTRODUCTION

Inadequate fluid status remains a key driver of cardiovascular morbidity and mortality in chronic hemodialysis (HD) patients. Quantification of fluid overload (FO) using bioimpedance spectroscopy (BIS) has become standard in many countries. To date, no BIS device has been approved in the United States for fluid status assessment in kidney patients. Therefore, no previous quantification of fluid status in US kidney patients using BIS has been reported. Our aim was to conduct a cross-sectional BIS-based assessment of fluid status in an urban US HD population.

METHODS

We determined fluid status in chronic HD patients using whole body BIS (Body Composition Monitor, BCM). The BCM reports FO in liters; negative FO denotes fluid depletion. Measurements were performed before dialysis. Post-HD FO was estimated by subtracting the intradialytic weight loss from the pre-HD FO.

FINDINGS

We studied 170 urban HD patients (age 61 ± 14 years, 60% male). Pre- and post-HD FO (mean ± SD), were 2.2 ± 2.4 and -0.2 ± 2.7 L, respectively. Pre-HD, 43% of patients were fluid overloaded, 53% normally hydrated, and 4% fluid depleted. Post-HD, 12% were fluid overloaded, 55% normohydrated and 32% fluid depleted. Only 48% of fluid overloaded patients were hypertensive, while 38% were normotensive and 14% hypotensive. Fluid status did not differ significantly between African Americans (N = 90) and Caucasians (N = 61).

DISCUSSION

While about half of the patients had normal fluid status pre-HD, a considerable proportion of patients was either fluid overloaded or depleted, indicating the need for tools to objectively quantify fluid status.

Current clinical practice in adapted automated peritoneal dialysis (aAPD)-A prospective, non-interventional study

Adapted automated peritoneal dialysis (aAPD), comprising a sequence of dwells with different durations and fill volumes, has been shown to enhance both ultrafiltration and solute clearance compared to standard peritoneal dialysis with constant time and volume dwells. The aim of this non-interventional study was to describe the different prescription patterns used in aAPD in clinical practice and to observe outcomes characterizing volume status, dialysis efficiency, and residual renal function over 1 year. Prevalent and incident, adult aAPD patients were recruited during routine clinic visits, and aAPD prescription, volume status, residual renal function and laboratory data were documented at baseline and every quarter thereafter for 1 year. Treatments were prescribed according to the nephrologist's medical judgement in accordance with each center's clinical routine. Of 180 recruited patients, 160 were analyzed. 27 different aAPD prescription patterns were identified. 79 patients (49.4%) received 2 small, short dwells followed by 3 long, large dwells. During follow-up, volume status changed only marginally, with visit mean values ranging between 1.59 (95% confidence interval: 1.19; 1.99) and 1.97 (1.33; 2.61) L. Urine output and creatinine clearance decreased significantly, accompanied by reductions in ultrafiltration and Kt/V. 25 patients (15.6%) received a renal transplant and 15 (9.4%) were changed to hemodialysis. Options for individualization offered by aAPD are actually used in practice for optimized treatment. Changes observed in renal function and dialysis efficiency measures reflect the natural course of chronic kidney disease. No safety events were observed during the study period.

Characteristics of bioimpedance-determined fluid shifts according to intradialytic blood pressure difference

This study was designed to identify the fluid spaces that are most changed during ultrafiltration (UF) according to intradialytic blood pressure (BP) difference. BP data were collected five times (before hemodialysis [HD] and 1–4 h of HD). Intradialytic BP difference was calculated as the highest minus lowest of these BP measurements. Intradialytic systolic BP (SBP) difference over 20 mm Hg and diastolic BP (DBP) difference over 10 mm Hg were defined as wide intradialytic SBP difference (SYS-W) and DBP difference (DIA-W), respectively. We measured the various fluid spaces before HD and 1–4 h of HD, and 30 min after HD using a portable, whole-body bioimpedance spectroscopy (BIS). In this study, 85 prevalent patients aged over 18 years with a fixed dry weight (65.38 ± 12.45 years, 54.18% men, 52.50% patients with diabetes), undergoing HD had participated. 1) Mean relative reduction of extracellular water (ECW) was significantly higher in SYS-W than in narrow intradialytic SBP difference (SYS-N) patients from 1 h to 30 min after HD. 2) Mean relative reduction of intracellular water (ICW) was significantly lower in DIA-W than in narrow intradialytic DBP difference (DIA-N) patients from 1 h to 30 min after HD. 3) ECW of patients with SYS-W was significantly lower than that of patients with SYS-N. Patients with SYS-W have the characteristics of fluid shifts in which reduction of ECW was steeper than patients with SYS-N whereas fluid shifts of ICW were lower in patients with DIA-W than patients with DIA-N.

Toward an individualized determination of dialysis adequacy: a narrative review with special emphasis on incremental hemodialysis

INTRODUCTION

The search for the 'perfect' renal replacement therapy has been paralleled by the search for the perfect biomarkers for assessing dialysis adequacy. Three main families of markers have been assessed: small molecules (prototype: urea); middle molecules (prototype β2-microglobulin); comprehensive and nutritional markers (prototype of the simplified assessment, albumin levels; composite indexes as malnutrition-inflammation score). After an era of standardization of dialysis treatment, personalized dialysis schedules are increasingly proposed, challenging the dogma of thrice-weekly hemodialysis.

AREAS COVERED

In this review, we describe the advantages and limitations of the approaches mentioned above, focusing on the open questions regarding personalized schedules and incremental hemodialysis.

EXPERT OPINION

In the era of personalized dialysis, the assessment of dialysis adequacy should be likewise personalized, due to the limits of 'one size fits all' approaches. We have tried to summarize some of the relevant issues regarding the determination of dialysis adequacy, attempting to adapt them to an elderly, highly comorbidity population, which would probably benefit from tailor-made dialysis prescriptions. While no single biomarker allows precisely tailoring the dialysis dose, we suggest using a combination of clinical and biological markers to prescribe dialysis according to comorbidity, life expectancy, residual kidney function, and small and medium-size molecule depuration.

The Effects of Oral Energy-Dense Supplements on Nutritional Status in Nondiabetic Maintenance Hemodialysis Patients: A Randomized Controlled Trial

BACKGROUND AND OBJECTIVES

Fat-based energy-dense nutritional supplements may offer benefits over protein- or carbohydrate-dense supplements for patients receiving dialysis because of the adverse metabolic consequences of the latter. We conducted a randomized controlled trial to assess the effects of the short-term use of a fat-based nutritional supplement on various measures of nutritional status in patients receiving maintenance hemodialysis who have low dietary energy intake.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We enrolled nondiabetic patients receiving hemodialysis for >3 months who had inadequate dietary energy intake (<30 kcal/kg per day). The participants were randomly assigned in a 1:1 ratio to receive an oral fat-based energy-dense supplement (300 kcal daily) or routine care for 12 weeks (n=120 per group). The primary outcome was the change in phase angle measured by bioelectrical impedance analysis, a marker of cell integrity and body cell mass, from the baseline to week 12. The secondary outcomes were changes in quality of life. Other outcomes included laboratory nutritional indicators and physical examinations.

RESULTS

The average age of the total population was 47 (SD: 12) years, and 55% were men. The median of dialysis vintage was 43.4 (22.5-76.3) months; 240 participants were randomly assigned to the intervention (n=120) or control group (n=120). In total, 228 (95%) participants completed the trial. The change in phase angle did not differ significantly between the intervention and control groups (estimate, 0.0; 95% confidence interval, -0.1 to 0.1 versus estimate, 0.0; 95% confidence interval, -0.1 to 0.1; estimated difference, 0.0; 95% confidence interval -0.2 to 0.2; P=0.99). None of the 19 domains of quality of life differed between the groups. Adverse events were reported in 23 (19%) participants in the control group and 40 (33%) participants in the intervention group.

CONCLUSIONS

In nondiabetic patients on maintenance hemodialysis, short-term administration of fat-based energy-dense nutritional supplement has no clinically significant effect on nutritional status as measured by phase angle.

PODCAST

This article contains a podcast at https://https://www.asn-online.org/media/podcast/CJASN/2021_08_03_CJN16821020.mp3.

Clinical Epidemiology of Systolic and Diastolic Orthostatic Hypotension in Patients on Peritoneal Dialysis

Blood pressure changes upon standing reflect a hemodynamic response, which depends on the baroreflex system and euvolemia. Dysautonomia and fluctuations in blood volume are hallmarks in kidney failure requiring replacement therapy. Orthostatic hypotension has been associated with mortality in hemodialysis patients, but neither this relationship nor the impact of changes in blood pressure has been tested in patients on peritoneal dialysis. We investigated both these relationships in a cohort of 137 PD patients. The response to orthostasis was assessed according to a standardized protocol. Twenty-five patients (18%) had systolic orthostatic hypotension, and 17 patients (12%) had diastolic hypotension. The magnitude of systolic and diastolic BP changes was inversely related to the value of the corresponding supine BP component (r = -0.16, p = 0.056 (systolic) and r = -0.25, p = 0.003 (diastolic), respectively). Orthostatic changes in diastolic, but not in systolic, BP were linearly related to the death risk (HR (1 mmHg reduction): 1.04, 95% CI 1.01-1.07, p = 0.006), and this was also true for CV death (HR: 1.08, 95% CI 1.03-1.12, p = 0.001). The strength of this association was not affected by further data adjustment (p ≤ 0.05). These findings suggest that independent of the formal diagnosis of orthostatic hypotension, even minor orthostatic reductions in diastolic BP bear an excess death risk in this population.

Chest Ultrasound as a New Tool for Assessment of Volume Status in Hemodialysis Patients

Accurate assessment of volume status (VS) in hemodialysis (HD) patients is challenging. The use of chest ultrasound (CUS) for detection of extravascular lung water has recently gained wide acceptance. The aim of this study was to evaluate the use of CUS in VS assessment in HD patients in comparison to clinical and inferior vena cava (IVC) indices and to assess their relation with volume displacement after ultrafiltration. This prospective cohort study was carried out on 38 patients on regular HD. VS was assessed using a 13-point clinical score, and IVC indices and CUS score were measured pre- and post-ultrafiltration. Correlation between these parameters and with ultrafiltration volume was tested. There was a statistically significant reduction in post-ultrafiltration CUS score and the 13-point clinical score (P < 0.01). Moreover, reduction in all the IVC indices (inspiratory and expiratory diameters and collapsing index) was detected, but did not reach statistical significance (P = 0.185, P = 0.296, and P = 0.194, respectively). CUS score had statistically significant correlations with ultrafiltration volume and New York Heart Association classes (P < 0.001 and <0.001, respectively). Neither clinical signs nor IVC indices can be used independently for the assessment of VS in HD patients. CUS is a useful guide in VS assessment, and we recommend its routine use in the management of HD patients. Concomitant use of bio- impedance analysis (BIA) may be needed in addition to CUS for more accurate assessment of VS in HD patients.

Volume overload in hemodialysis: diagnosis, cardiovascular consequences, and management

Volume overload in haemodialysis (HD) patients associates with hypertension and cardiac dysfunction and is a major risk factor for all-cause and cardiovascular mortality in this population. The diagnosis of volume excess and estimation of dry weight is based largely on clinical criteria and has a notoriously poor diagnostic accuracy. The search for accurate and objective methods to evaluate dry weight and to diagnose subclinical volume overload has been intensively pursued over the last 3 decades. Most methods have not been tested in appropriate clinical trials and their usefulness in clinical practice remains uncertain, except for bioimpedance spectroscopy and lung ultrasound (US). Bioimpedance spectroscopy is possibly the most widely used method to subjectively quantify fluid distributions over body compartments and produces reliable and reproducible results. Lung US provides reliable estimates of extravascular water in the lung, a critical parameter of the central circulation that in large part reflects the left ventricular end-diastolic pressure. To maximize cardiovascular tolerance, fluid removal in volume-expanded HD patients should be gradual and distributed over a sufficiently long time window. This review summarizes current knowledge about the diagnosis, prognosis and treatment of volume overload in HD patients.

Pilot study to reduce interdialytic weight gain by provision of low-sodium, home-delivered meals in hemodialysis patients

INTRODUCTION

Patients with kidney failure undergoing maintenance hemodialysis (HD) therapy are routinely counseled to reduce dietary sodium intake to ameliorate sodium retention, volume overload, and hypertension. However, low-sodium diet trials in HD are sparse and indicate that dietary education and behavioral counseling are ineffective in reducing sodium intake. This study aimed to determine whether 4 weeks of low-sodium, home-delivered meals in HD patients reduces interdialytic weight gain (IDWG). Secondary outcomes included changes in dietary sodium intake, thirst, xerostomia, blood pressure, volume overload, and muscle sodium concentration.

METHODS

Twenty HD patients (55 ± 12 years, body mass index [BMI] 40.7 ± 16.6 kg/m² ) were enrolled in this study. Participants followed a usual (control) diet for the first 4 weeks followed by 4 weeks of three low-sodium, home-delivered meals per day. We measured IDWG, hydration status (bioimpedance), standardized blood pressure (BP), food intake (3-day dietary recall), and muscle sodium (magnetic resonance imaging) at baseline (0 M), after the 4-week period of usual diet (1 M), and after the meal intervention (2 M).

FINDINGS

The low-sodium meal intervention significantly reduced IDWG when compared to the control period (-0.82 ± 0.14 kg; 95% confidence interval, -0.55 to -1.08 kg; P < 0.001). There were also 1 month (1 M) to 2 month (2 M) reductions in dietary sodium intake (-1687 ± 297 mg; P < 0.001); thirst score (-4.4 ± 1.3; P = 0.003), xerostomia score (-6.7 ± 1.9; P = 0.002), SBP (-18.0 ± 3.6 mmHg; P < 0.001), DBP (-5.9 ± 2.0 mmHg; P = 0.008), and plasma phosphorus -1.55 ± 0.21 mg/dL; P = 0.005), as well as a 0 M to 2 M reduction in absolute volume overload (-1.08 ± 0.33 L; P = 0.025). However, there were no significant changes in serum or tissue sodium (all P > 0.05).

DISCUSSION

Low-sodium, home-meal delivery appears to be an effective method for improving volume control and blood pressure in HD patients. Future studies with larger sample sizes are needed to examine the long-term effects of home-delivered meals on these outcomes and to assess cost-effectiveness.

Implementation of a decision aid for recognition and correction of volume alterations (Recova®) in haemodialysis patients

BACKGROUND

Fluid overload is associated with mortality in haemodialysis patients, and 30% of patients remain fluid-overloaded after dialysis. The aim of this study was to evaluate if implementation of Recova^®, a decision aid combining clinical assessment with bioimpedance spectroscopy, facilitates individualization of target weight determination and thereby contributes to improved fluid status in maintenance haemodialysis patients.

METHODS

The impact of the implementation was measured as the proportion of participants at an adequate target weight at the end of the study, assessed as change in symptoms, hydration status, and N-terminal pro-brain natriuretic peptide (NT-proBNP). Nurses were instructed to use Recova every 2 weeks, and the process of the intervention was measured as frequencies of fluid status assessments, bioimpedance measurements, and target weight adjustments.

RESULTS

Forty-nine patients at two haemodialysis units were enrolled. In participants with fluid overload (n = 10), both overhydration and fluid overload symptom score decreased. In fluid-depleted participants (n = 20), target weight adjustment frequency and the estimated target weight increased. The post-dialytic negative overhydration was reduced, but NT-proBNP increased.

CONCLUSIONS

Implementation of Recova in haemodialysis care increased the monthly frequencies of bioimpedance measurements and target weight adjustments, and it contributed to symptom reduction.

TRIAL REGISTRATION

The Uppsala County Council Registry of Clinical Trials: FoU 2019-0001-15.

Comparison between lung ultrasonography and current methods for volume assessment in Asian chronic hemodialysis patients

INTRODUCTION

Volume assessment in end-stage kidney disease patients on hemodialysis (HD) remains inadequate by existing methods: clinical examination, bioimpedance spectroscopy, measurement of inferior vena cava diameter by ultrasound (IVCD), and plasma B-type natriuretic peptide (NT-pro BNP). This study aims to compare the performance of lung ultrasound against existing methods for volume assessment in a HD cohort.

METHODS

Two nephrologists independently performed 28-point lung ultrasound immediately before and after midweek HD in 50 patients. Lung congestion was classified into mild, moderate, and severe categories based on lung ultrasound findings. Clinical examination for crepitations and oedema, change in hydration status (∆HS) measured by bioimpedance spectroscopy, NT-pro BNP, IVCD during inspiration (IVCDimin), expiration (IVCDimax), and inferior vena cava collapsibility index were also assessed before and after midweek HD.

FINDINGS

In all, 61% of patients with normohydration status by bioimpedance spectroscopy had moderate or severe lung congestion on lung ultrasound. There were significant correlations between predialysis lung ultrasound, and NT-pro BNP (r = 0.432, P = 0.004), ∆HS (r = 0.447, P < 0.001), and IVCD parameters (P < 0.05). Some correlations weakened postdialysis (∆HS [r = 0.322, P = 0.01] and IVCDimax [r = 0.307, P = 0.03]), whereas NT-pro BNP and ∆HS paradoxically increased in 28% and 30% of the cohort, respectively. On receiver operator curve analysis, most methods of volume assessment had limited discriminatory power to detect mild lung congestion.

DISCUSSION

Lung ultrasound demonstrates some comparability with existing volume assessment methods in Asian dialysis patients. However, it appears more effective at detecting subclinical pulmonary congestion, and tracking fluid changes real-time compared to bioimpedance spectroscopy and NT-pro BNP.

Extracellular fluid volume expansion, arterial stiffness and uncontrolled hypertension in patients with chronic kidney disease

BACKGROUND

Hypertension is prevalent in patients with chronic kidney disease (CKD) and is related to extracellular fluid volume (ECFV) expansion. Arterial stiffening is another implication of CKD that can be caused by ECFV expansion. In this study, we hypothesized that CKD patients with uncontrolled hypertension are more likely to be fluid volume expanded than normotensive patients, which in turn is associated with increased arterial stiffness.

METHODS

Adult hypertensive patients with mild-severe CKD (n = 82) were recruited. ECFV was assessed using multifrequency bioimpedance and arterial stiffness by applanation tonometry and oscillometry.

RESULTS

Patients with uncontrolled hypertension had fluid volume expansion compared with controls (1.0 ± 1.5 versus 0.0 ± 1.6 L, P < 0.001), and had a higher augmentation index (AIx) and pulse wave velocity. Fluid volume expansion was more prevalent in patients with uncontrolled hypertension (58%) than patients who were at target (27%). Fluid volume expansion was correlated with age, AIx and systolic blood pressure. In a binary logistic regression analysis, AIx, age and fluid volume status were independent predictors of uncontrolled hypertension in both univariate and multivariate models.

DISCUSSION

In summary, uncontrolled hypertension among hypertensive CKD patients is associated with ECFV expansion. Our data suggest a relationship between ECFV expansion, increased arterial stiffness and uncontrolled hypertension.

Serum levels of protein carbonyl, a marker of oxidative stress, are associated with overhydration, sarcopenia and mortality in hemodialysis patients

Background

Increased oxidative stress in end-stage renal disease is regarded as one of the important mechanisms in the atherosclerosis and muscle wasting. However, studies examining the clinical significance of oxidative stress by direct measurement of these markers and its association with volume status and sarcopenia are limited.

Methods

A follow-up cross-sectional study was performed in stable hemodialysis (HD) patients and serum protein carbonyl levels were measured as a biomarker of oxidative stress. Additionally, multi-frequency body composition analysis, handgrip strength (HGS) and nutritional assessments were performed at baseline.

Results

Eighty-eight patients undergoing HD were included and 30 (34.1%) patients died during a mean follow-up of 5.2 years. The mean patient age was 60.6 ± 13.5 years, and the mean HD duration was 50.8 ± 41.3 months. In total, 16 patients (18.2%) were overhydrated, 49 (55.7%) had low HGS and 36 (40.9%) had low muscle mass. Serum protein carbonyl levels were associated with serum levels of albumin, prealbumin and transferrin, hydration status and low HGS. Overhydration (odds ratio [OR] 7.01, 95% CI 1.77–27.79, p = 0.006), prealbumin (OR 0.91, 95% CI 0.83–0.99, p = 0.030), subjective global assessment (OR 3.52, 95% CI 1.08–11.46, p = 0.037) and sarcopenia (OR 3.41, 95% CI 1.02–11.32, p = 0.046) were significantly related to increased serum protein carbonyl levels. Multivariate analysis showed that the serum levels of protein carbonyl (Hazard ratio [HR] 2.37, 95% CI 1.02–5.55, p = 0.036), albumin (HR 0.17, 95% CI 0.06–0.46, p = 0.003), prealbumin (HR 0.86, 95% CI 0.80–0.92, p = 0.001), overhydration (HR 2.31, 95% CI 1.26–8.71, p = 0.015) and sarcopenia (HR 2.72, 95% CI 1.11–6.63, p = 0.028) were independent determinants of all-cause mortality.

Conclusions

Serum protein carbonyl was significantly associated with overhydration, nutritional status and sarcopenia, and could be a new predictor of mortality in patients undergoing HD.

Fluid and hemodynamic management in hemodialysis patients: challenges and opportunities

Fluid volume and hemodynamic management in hemodialysis patients is an essential component of dialysis adequacy. Restoring salt and water homeostasis in hemodialysis patients has been a permanent quest by nephrologists summarized by the ‘dry weight’ probing approach. Although this clinical approach has been associated with benefits on cardiovascular outcome, it is now challenged by recent studies showing that intensity or aggressiveness to remove fluid during intermittent dialysis is associated with cardiovascular stress and potential organ damage. A more precise approach is required to improve cardiovascular outcome in this high-risk population. Fluid status assessment and monitoring rely on four components: clinical assessment, non-invasive instrumental tools (e.g., US, bioimpedance, blood volume monitoring), cardiac biomarkers (e.g. natriuretic peptides), and algorithm and sodium modeling to estimate mass transfer. Optimal management of fluid and sodium imbalance in dialysis patients consist in adjusting salt and fluid removal by dialysis (ultrafiltration, dialysate sodium) and by restricting salt intake and fluid gain between dialysis sessions. Modern technology using biosensors and feedback control tools embarked on dialysis machine, with sophisticated analytics will provide direct handling of sodium and water in a more precise and personalized way. It is envisaged in the near future that these tools will support physician decision making with high potential of improving cardiovascular outcome.

An analysis of the impact of fluid overload and fluid depletion for all-cause and cardiovascular mortality

BACKGROUND

Both baseline fluid overload (FO) and fluid depletion are associated with increased mortality risk and cardiovascular complications in haemodialysis patients. Fluid status may vary substantially over time, and this variability could also be associated with poor outcomes.

METHODS

In our retrospective cohort study, including 4114 haemodialysis patients from 34 Romanian dialysis units, we investigated both all-cause and cardiovascular mortality risk according to baseline pre- and post-dialysis volume status, changes in pre- and post-dialysis fluid status during follow-up (time-varying survival analysis), pre-post changes in volume status during dialysis and pre-dialysis fluid status variability during the first 6 months of evaluation.

RESULTS

According to their pre-dialysis fluid status, patients were stratified in the following groups: normovolaemic with an absolute FO (AFO) compartment between -1.1 and 1.1 L, fluid depletion with an AFO below -1.1 L, moderate FO with an AFO compartment >1.1 but <2.5 L and severe FO with the AFO compartment >2.5 L. Baseline pre-dialysis FO and fluid depletion patients had a significantly elevated risk of all-cause mortality risk {hazard ratio [HR] 1.53 [95% confidence interval (CI) 1.22-1.93], HR 2.04 (95% CI 1.59-2.60) and HR 1.88 (95% CI 1.07-3.39) for moderate FO, severe FO and fluid depletion, respectively}. In contrast, post-dialysis fluid depletion was associated with better survival [HR 0.71 (95% CI 0.57-0.89)]. Similar results were found when using changes in pre- or post-dialysis fluid status during follow-up (time-varying values): FO patients had an increased risk of all-cause [moderate FO: HR 1.39 (95% CI 1.11-1.75); severe FO: HR 2.29 (95% CI 2.01-3.31] and cardiovascular (CV) mortality [moderate FO: HR 1.34 (95% CI 1.05-1.70); severe FO: HR 2.34 (95% CI 1.67-3.28)] as compared with normohydrated patients. Using pre-post changes in volume status during dialysis, we categorized the patients into six groups: Group 1, AFO <-1.1 L pre- and post-dialysis; Group 2, AFO between -1.1 and 1.1 L pre-dialysis and <-1.1 L post-dialysis (the reference group); Group 3, AFO between -1.1 and 1.1 L pre- and post-dialysis; Group 4, AFO >1.1 L pre-dialysis and <-1.1 L post-dialysis; Group 5, AFO >1.1 L pre-dialysis and between -1.1 and 1.1 L post-dialysis; Group 6, AFO >1.1 L pre- and post-dialysis. Using the baseline values, only patients in Groups 1, 5 and 6 maintained an increased risk for all-cause mortality as compared with the reference group. Additionally, CV mortality risk was significantly higher for patients in Groups 5 and 6. When we applied the time-varying analysis, patients in Groups 1, 5 and 6 had a significantly higher risk for both all-cause and CV mortality risk. In the last approach, the highest risk for the all-cause mortality outcome was observed for patients with high-amplitude fluctuation during the first 6 months of evaluation [HR 2.75 (95% CI 1.29-5.84)].

CONCLUSION

We reconfirm the association between baseline pre- and post-dialysis volume status and mortality in dialysis patients; additionally, we showed that greater fluid status variability is independently associated with higher mortality.

The Nephrologist as an Ultrasonographer

Ultrasonography is increasingly being used in the practice of nephrology, whether it is for diagnosis or management of acute or chronic kidney dysfunction, until progression to end-stage kidney disease, including preoperative assessment, access placement, and diagnosis and management of dysfunctional hemodialysis access. Point-of-care ultrasounds are also being used by nephrologists to help manage volume status, especially in patients admitted to the intensive care units, and more recently, for guiding fluid removal in the outpatient dialysis units. Fundamental knowledge of sonography has become invaluable to the nephrologist, and performance and interpretation of ultrasound has now become an essential tool for practicing nephrologists to provide patient-centered care, maximize efficiency, and minimize fragmentation of care. This review will address the growing role of ultrasonography in the management of a patient with CKD from the point of initial contact with the nephrologist throughout the spectrum of kidney disease and its consequences.

The effect of BCM guided dry weight assessment on short-term survival in Chinese hemodialysis patients : Primary results of a randomized trial - BOdy COmposition MOnitor (BOCOMO) study

BACKGROUND

Lack of accurate and effective assessment tools of fluid status is one of the major challenges to reach proper dry weight (DW) in chronic hemodialysis (HD) population. The aim of this randomized study was to evaluate the effect of bioimpedance guided DW assessment on long-term outcomes in Chinese HD patients. Eligible patients were randomly assigned (1:1) to two groups in each center, the control group and body composition monitor (BCM) group. In the BCM group, DW has been evaluated by bioimpedance technic every 2 months during follow-up. The primary composite endpoint consisted of death, acute myocardial infarction, cerebral infarction, cerebral hemorrhage, and peripheral vascular disease.

METHODS

A total of 445 patients were recruited from 11 hemodialysis centers from Beijing, Tianjin and Shijiazhuang cities from Jan 1, 2013 to Dec 31, 2014. They were randomized into either BCM group or control group. All patients have been followed up for 1 year or until Dec 31, 2014 or censoring.

RESULTS

At baseline, there were no significant differences between two groups in terms of demographic parameters, dialysis vintage, percentage of vascular access, and comorbid conditions. At the end of the study, 18 (4.04%) patients had died (11 in control group and 7 in BCM group). Kaplan-Meier survival analysis showed no significant difference in survival rates between two groups (log-rank test P = 0.07). However, there was an increasing trend of survival rates in BCM group compared to the control group. In the multivariable Cox analysis, there was a nonsignificant trend toward less primary composite end points in the BCM group in the adjusted analysis, the hazard ratio was impressive (0.487, 95% CI 0.217-1.091, P = 0.08).

CONCLUSION

Bioimpedance technic has been applied to assess fluid status for decades and has been proved to be a promising tool for clinical practice. Although short-term outcomes were not improved in the randomized, controlled trial, the ascending trend in survival has been observed. Further studies are needed to investigate the survival benefit of bioimpedance method in DW assessment in a larger sample with longer follow-up period.

TRIAL REGISTRATION

ClinicalTrials.org, NCT01509937. Registered 13 January 2012.

Uncertainties in BP management in dialysis patients

Hypertension in dialysis patients is extremely common. In this article, we review the current evidence for blood pressure (BP) goals in hemodialysis patients, and consider the effectiveness of interventions by which BP may be lowered, including manipulation of dietary and dialysate sodium; optimization of extracellular water; prolongation of dialysis time; and antihypertensive medication. Although two meta-analyses suggest lowering BP using antihypertensive drugs might be beneficial in reducing cardiovascular events and mortality, there are insufficient rigorously designed trials in hypertensive hemodialysis populations to determine preferred antihypertensive drug classes. We suggest aiming for predialysis systolic BP between 130 and 159 mm Hg, while at the same time acknowledge the significant limitations of the data upon which it is based. We conclude by summarizing current knowledge as regards management of hypertension in the peritoneal dialysis population and make recommendations for future research in this field.

Factors Contributing to Formation of Edema in Volume Overloaded Continuous Ambulatory Peritoneal Dialysis Patients

Background

Volume control is critical for the success of peritoneal dialysis (PD) but dry weight in PD has been difficult to obtain. Edema free is, in general, accepted clinically as a target for volume control in PD patients. However, PD patients can be free of edema despite significant volume overload. The present study investigates the possible factors that influence the formation of pitting edema in volume-overloaded PD patients.

Methods

In this cross-sectional study, patients’ fluid status was evaluated by multifrequency bioelectrical impedance spectroscopy analysis. Values for overhydration were obtained. Patients with overhydration ≥ 2.0 kg were considered volume overloaded and were eligible for inclusion. From 1 March 2009 to 1 December 2009, a total of 96 patients on continuous ambulatory PD were included. Endothelial function was evaluated by flow-mediated dilatation (FMD). Other clinical indicators, such as blood pressure, dialysis adequacy, nutrition status, and biochemical parameters, were recorded. Patients were divided into 2 groups based on edema status: the edema group ( n = 35 volume-overloaded patients with bilateral pitting edema) and the non-edema group ( n = 61 volume-overloaded patients without bilateral pitting edema).

Results

Overhydration in the edema group was significantly higher than in the non-edema group (4.28 ± 1.75 kg vs 3.12 ± 0.81 kg, p < 0.001), whereas both FMD and serum albumin in the edema group were significantly lower than in the non-edema group (6.65% ± 5.2% vs 10.3% ± 5.1%, p = 0.001; 37.6 ± 4.2 g/L vs 39.3 ± 3.5 g/L, p = 0.047, respectively). Edema status (edema = 1, non-edema = 0) was positively correlated with overhydration ( r = 0.341, p < 0.001), gender (male = 1, female = 2: r = 0.184, p = 0.072), and total fluid removal ( r = 0.188, p = 0.074) and negatively correlated with endothelial function, as assessed by FMD ( r = -0.33, p = 0.001), and serum albumin ( r = -0.18, p = 0.055). Logistic regression analysis showed that FMD [odds ratio (OR) 0.90, 95% confidence interval (CI) 0.81 - 0.99; p = 0.036], gender (male = 1, female = 2: OR 4.06, 95% CI 1.23 - 13.35; p = 0.021), overhydration (OR 3.06, 95% CI 1.53 - 6.13; p = 0.002), and serum albumin (OR 0.86, 95% CI 0.75 - 0.99; p = 0.035) were independent factors affecting the edema status of the study population.

Conclusion

Our study showed that endothelial function (assessed by FMD), gender, serum albumin, and over hydration are independent determinants of edema status in PD patients. This may explain why some PD patients can maintain free of edema despite significant volume overload.

Sodium and water handling during hemodialysis: new pathophysiologic insights and management approaches for improving outcomes in end-stage kidney disease

Space medicine and new technology such as magnetic resonance imaging of tissue sodium stores (²³NaMRI) have changed our understanding of human sodium homeostasis and pathophysiology. It has become evident that body sodium comprises 3 main components. Two compartments have been traditionally recognized, namely one that is circulating and systemically active via its osmotic action, and one slowly exchangeable pool located in the bones. The third, recently described pool represents sodium stored in skin and muscle interstitium, and it is implicated in cell and biologic activities via local hypertonicity and sodium clearance mechanisms. This in-depth review provides a comprehensive view on the pathophysiology and existing knowledge gaps of systemic hemodynamic and tissue sodium accumulation in dialysis patients. Furthermore, we discuss how the combination of novel technologies to quantitate tissue salt accumulation (e.g., ²³NaMRI) with devices to facilitate the precise attainment of a prescribed hemodialytic sodium mass balance (e.g., sodium and water balancing modules) will improve our therapeutic approach to sodium management in dialysis patients. While prospective studies are required, we think that these new diagnostic and sodium balancing tools will enhance our ability to pursue more personalized therapeutic interventions on sodium and water management, with the eventual goal of improving dialysis patient outcomes.

The impact of volume overload on technique failure in incident peritoneal dialysis patients

Background

Technique failure in peritoneal dialysis (PD) can be due to patient- and procedure-related factors. With this analysis, we investigated the association of volume overload at the start and during the early phase of PD and technique failure.

Methods

In this observational, international cohort study with longitudinal follow-up of incident PD patients, technique failure was defined as either transfer to haemodialysis or death, and transplantation was considered as a competing risk. We explored parameters at baseline or within the first 6 months and the association with technique failure between 6 and 18 months, using a competing risk model.

Results

Out of 1092 patients of the complete cohort, 719 met specific inclusion and exclusion criteria for this analysis. Being volume overloaded, either at baseline or Month 6, or at both time points, was associated with an increased risk of technique failure compared with the patient group that was euvolaemic at both time points. Undergoing treatment at a centre with a high proportion of PD patients was associated with a lower risk of technique failure.

Conclusions

Volume overload at start of PD and/or at 6 months was associated with a higher risk of technique failure in the subsequent year. The risk was modified by centre characteristics, which varied among regions.

The Effect of Strict Volume Control Assessed by Repeated Bioimpedance Spectroscopy on Cardiac Function in Peritoneal Dialysis Patients

Adequate fluid management plays an important role in decreasing cardiovascular risk in peritoneal dialysis (PD) patients. We evaluated whether strict volume control monitored by bioimpedance spectroscopy (BIS) affects cardiac function in PD patients. This study is a secondary analysis of a multicentre, prospective, randomized, controlled trial. Fluid overload was assessed by the average overhydration/extracellular water (OH/ECW) at baseline, 6 months and 12 months. Patients were categorized as time-averaged overhydrated (TA-OH/ECW ≥15%) or normohydrated (TA-OH/ECW <15%), and echocardiographic parameters were compared between groups. Among a total of 151 patients, 120 patients exhibited time-averaged normohydration. Time-averaged overhydrated patients had a significantly higher left atrial (LA) diameter and E/e′ ratio and a lower left ventricular (LV) ejection fraction at 12 months than time-averaged normohydrated patients. LA diameter, end-systolic volume and end-diastolic volume were decreased at 12 months compared to baseline in time-averaged normohydrated patients only. TA-OH/ECW was independently associated with ejection fraction at 12 months (β = −0.190; p = 0.010). TA-OH/ECW, but not OH/ECW at 12 months, was an independent risk factor for LV dysfunction (odds ratio 4.020 [95% confidence interval 1.285–12.573]). Overhydration status based on repeated BIS measurements is an independent predictor of LV systolic function in PD patients.

Systematic Fluid Assessment in Haemodialysis: Development and Validation of A Decision Aid

BACKGROUND

About a third of patients undergoing haemodialysis have poorly controlled fluid status, which may affect survival. Clinical assessment is subjective and imprecise, which has led to the increasing use of devices based on bioimpedance spectroscopy (BIS). However, BIS cannot provide a simple target applicable to all patients. Our aim was to develop and validate a decision aid combining clinical assessment of fluid status with information from BIS in target weight determination.

METHODS

The decision aid was based on empirical experience and a literature review identifying physiological parameters already used in the clinical assessment of fluid status. Content validity was established by patient representatives, interdisciplinary stakeholders and external experts, who assessed item relevance and comprehensiveness. Reliability was assessed by inter-rater agreement analysis between nurses assessing typical patient cases.

RESULTS

The decision aid for Recognition and Correction of Volume Alterations (RECOVA) consists of three parts (1) a scoring system; (2) thresholds and triggers; (3) a decision aid algorithm. Agreement between raters in the assessment of symptoms was almost perfect, with Intraclass Correlation Coefficient > 0.90. Agreement in clinical response was only fair, but increased to moderate, with training and self-reported confidence.

CONCLUSION

RECOVA may enable systematic clinical assessment of fluid status, facilitating early recognition of fluid alterations, and incorporation of bioimpedance into target weight management. However, implementation into clinical practice will require training of staff. Clinical intervention studies are required to evaluate if RECOVA facilitates response to and correction of recognised fluid alterations.

Pre-dialysis fluid status, pre-dialysis systolic blood pressure and outcome in prevalent haemodialysis patients: results of an international cohort study on behalf of the MONDO initiative

Background

Pre-dialysis fluid overload (FO) associates with mortality and causes elevated pre-dialysis systolic blood pressure (pre-SBP). However, low pre-SBP is associated with increased mortality in haemodialysis patients. The objective of this study was to investigate the interaction between pre-dialysis fluid status (FS) and pre-SBP in association with mortality.

Methods

We included all patients from the international Monitoring Dialysis Outcome Initiative (MONDO) database with a pre-dialysis multifrequency bioimpedance spectroscopy measurement in the year 2011. We used all parameters available during a 90-day baseline period. All-cause mortality was recorded during 1-year follow-up. Associations with outcome were assessed with Cox models and a smoothing spline Cox analysis.

Results

We included 8883 patients. In patients with pre-dialysis FO (>+1.1 to +2.5 L), pre-SBP <110 mmHg was associated with an increased risk of death {hazard ratio (HR) 1.52 [95% confidence interval (CI) 1.06-2.17]}. An increased risk of death was also associated with pre-dialysis fluid depletion (FD; <-1.1 L) combined with a pre-SBP <140 mmHg. In normovolemic (NV) patients, low pre-SBP <110 mmHg was associated with better survival [HR 0.46 (95% CI 0.23-0.91)]. Also, post-dialysis FD associated with a survival benefit. Results were similar when inflammation was present. Only high ultrafiltration rate could not explain the higher mortality rates observed.

Conclusion

The relation between pre-SBP and outcome is dependent on pre-dialysis FS. Low pre-SBP appears to be disadvantageous in patients with FO or FD, but not in NV patients. Post-dialysis FD was found to associate with improved survival. Therefore, we suggest interpreting pre-SBP levels in the context of FS and not as an isolated marker.