Volume Status In Dialysis Patients Research Articles

#1017 External validation of a machine learning model for the prediction of bioimpedance-determined pre-dialysis overhydration

Abstract Background and Aims An accurate, automated determination of volume status in dialysis patients using a reproducible standard would be clinically useful. We have previously developed a machine learning model for the prediction of pre-dialysis overhydration (OH) index (litres) from the Fresenius Body Composition Monitor (BCM). External validation is a requisite step before the clinical implementation of a machine learning model. Method Data analyses were performed using Python. An XGBoost regressor model was internally developed and validated in a Fresenius dataset of 9,452 patients and 279,324 BCM target events from the Czech Republic and Italy between January 2016 and December 2022. An XGBoost regressor model with 60 input variables including the average BCM OH value in the preceding year, 2-week moving averages of dialysis session data and biomarkers/ medications data from the preceding 13 weeks demonstrated the best performance of the models tested. The external validation (EV) dataset consisted of 24 patients from a 7-week observational study in a single centre, in Beaumont, Ireland comprising 94 BCM sessions and 650 haemodialysis sessions. Individualised predictions were compared with BCM measures and clinical volume assessments performed at 2-week intervals. Mean squared error (MSE), Root mean square error (RMSE), and Bland-Altman plots were used for continuous outcomes. Precision, recall and F1 score were used to assess the algorithm's performance in predicting the following fluid categories: overhydration ≥1.1L, normohydration −1.1L to 1.1L, underhydration ≤-1.1L. Normohydration weight was calculated by subtracting the predicted OH index from the pre-dialysis weight. Results There was performance degradation between the internal validation (IV) and EV set. The RMSE for pre-dialysis OH was 1.04 kg in the IV set and 1.5 kg in the EV set. This could be attributed to differences in the distribution of the outcome variable (BCM OH validation dataset=1.97 ± 1.56 kg*, EV dataset=0.89 ± 1.7 kg), and the case-mix. The RMSE for normohydration weight was 1.86 kg in the EV set. Wide limits of agreement were noted on a Bland Altman plot comparing the average of BCM and predicted values plotted against the difference in values (mean bias - 0.54, 95% limits of agreement -3.44 kg to 2.36 kg). The overall accuracy of the model in predicting fluid classes was 60%. A histogram showed a close alignment in the distributions of predicted normohydration weights and BCM values. Conclusion The performance of the algorithms degraded between the internal validation and external validation datasets. However, the pre-dialysis algorithm showed an ability to discriminate fluid categories compared to nursing staff and the overall accuracy was acceptable. Additional training of the algorithms using fluid status classes would be expected to improve the precision of predictions. *Values less than the 1st percentile of – 2.17 L were excluded.

Fluid management protocols in hemodialysis patients using bioimpedance validation: time to look elsewhere?

The management of volume status in dialysis patients is an important determinant of the rate of decline of residual kidney function. The implementation of clinical protocols to guide volume management in the in-center hemodialysis unit resulted in comparable rates of development of anuria and decline in residual kidney function when compared with bioimpedance spectroscopy-guided volume management. Clinical judgment and experience are important drivers of patient outcomes. The importance and applicability of bioimpedance spectroscopy in other clinical settings, such as units without clear volume management protocols or in home dialysis units, remain to be seen.

MO820INTRACELLULAR WATER BEFORE HEMODIALYSIS PREDICTS ALL-CAUSE MORTALITY IN HEMODIALYSIS PATIENTS

Abstract Background and Aims Several factors may be responsible for the increased mortality in dialysis patients, but volume overload is considered among the main mechanisms of this association. Volume status is usually estimated using clinical criteria, i.e., patien's signs and symptoms, peridialytic blood pressure measurements, and intradialytic hemodynamic instability. Bioimpedance analysis (BIA) is another way to measure volume status in dialysis patients. BIA can measure overhydration (OH), extracellular water (ECW), intracellular water (ICW) and ECW/ICW ratio. The aim of our study was to analyze the role of BIA parameters before and after hemodialysis (HD) on all-cause mortality. Method Eighty-three patients (mean age 64.2 years; 51 men) on maintenance HD were included. BIA was performed and blood pressure was measured before and after the HD session. Patients were followed for assigned time, until transplantation or death. The mean follow-up time was 1181±564 days. Results Descriptive statistics of our patients are shown in Table 1. During the follow-up period, 6 (7.2%) patients were transplanted and 39 (47%) patients died. Univariate Cox regression analysis showed that only ICW before HD was a significant predictor of all-cause mortality (HR=1.089; 95%CI: 1.01-1.17, p=0.018). OH, ECW, ECW/ICW ratio before and after HD and ICW after HD were not associated with survival. In multivariate Cox regression analysis including ICW before dialysis, age, dialysis vintage, pulse pressure before HD, hemoglobin, CRP and serum albumin, ICW before dialysis was an independent predictor of all-cause mortality (HR=1.102; 95%CI: 1.01-1.20, p=0.029) (Table 2). Conclusion ICW before HD predicts all-cause mortality in HD patients.

Clinical Relevance of Fluid Volume Status Assessment by Bioimpedance Spectroscopy in Children Receiving Maintenance Hemodialysis or Peritoneal Dialysis.

Bioimpedance spectroscopy (BIS) is a noninvasive method used to evaluate body fluid volume status in dialysis patients, but reports on its effectiveness in pediatrics are scarce. We investigated the correlation between BIS and clinical characteristics and identified the changes in patients whose dialysis prescription was modified based on BIS. The medical records of children on maintenance dialysis who had undergone BIS between 2017 and 2019 were reviewed. Of the 49 patients, 14 were overhydrated, based on the >15% proportion of overhydration relative to extracellular water (OH/ECW) measured by BIS. Intake of ≥two antihypertensive medications was noted in the majority (85.7%) of children with fluid overload and only in 48.6% of those without fluid overload (p = 0.017). Elevated blood pressure despite medication use was significantly more common in patients with fluid overload than in those without fluid overload (78.6% vs. 45.7%, p = 0.037). Of the 14 overhydrated children, 13 (92.9%) had significant changes in body weight, OH/ECW, the number of antihypertensive drugs, left ventricular end-diastolic diameter, and cardiothoracic ratio after the change in dialysis prescription. BIS is a useful and noninvasive method to assess fluid status in dialysis children. Long-term follow-up and correlation with a more objective clinical indicator of fluid overload is necessary to verify the clinical effectiveness of BIS.

Clinical efficacy of biomarkers for evaluation of volume status in dialysis patients.

Volume status is a key parameter for cardiovascular-related mortality in dialysis patients. Although N-terminal pro-B-type natriuretic peptide (NT-proBNP), myeloperoxidase, copeptin, and pro-adrenomedullin have been reported as volume markers, the relationship between body fluid status and volume markers in dialysis patients is uncertain. Therefore, we investigated the utility of volume status biomarkers based on body composition monitor (BCM) analyses.We enrolled pre-dialysis, hemodialysis (HD), and peritoneal dialysis (PD) patients and age- and gender-matched healthy Korean individuals (N = 80). BCM and transthoracic echocardiography were performed and NT-proBNP, myeloperoxidase, copeptin, and pro-adrenomedullin concentrations were measured. Relative hydration status (ΔHS, %) was defined in terms of the hydration status-to-extracellular water ratio with a cutoff of 15%, and hyperhydrated status was defined as ΔHS > 15%.Although there were no significant differences in total body water, extracellular water, or intracellular water among groups, mean amount of volume overload and hyperhydrated status were significantly higher in HD and PD patients compared with control and pre-dialysis patients. Mean amount of volume overload and hyperhydrated status were also significantly associated with higher NT-proBNP and pro-adrenomedullin levels in HD and PD patients, although not with myeloperoxidase or copeptin levels. Furthermore, they were significantly associated with cardiac markers (left ventricular mass index, ejection fraction, and left atrial diameter) in HD and PD patients compared with those in the control and pre-dialysis groups.On the basis of increased plasma NT-proBNP and pro-adrenomedullin concentrations, we might be able to make predictions regarding the volume overload status of dialysis patients, and thereby reduce cardiovascular-related mortality through appropriate early volume control.

Volume Assessment in Hemodialysis: A Comparison of Present Methods in Clinical Practice with Sonographic Lung Comets.

Dry weight assessment in dialysis patients remains a challenging endeavor owing to the limitations of the available methods for volume assessment. Lung ultrasound is emerging as an invaluable tool to assist in the appropriate assessment and assignment of dry weight. The objectives of this study are (1) to determine the reliability of clinical signs and symptoms for volume assessment, (2) to compare lung ultrasound with High Resolution Computed Tomography (HRCT) chest-A noninvasive gold standard tool for detecting pulmonary congestion and with inferior vena cava diameter (IVCD) – another time-tested volume assessment method, and (3) to analyze if lung ultrasound could detect dialysis induced fluid status variations. The cross-sectional study involves 50 patients on maintenance hemodialysis. Lung ultrasound for B line estimation and ultrasonographic measurement of IVCD performed before and after hemodialysis by a nephrologist trained in ultrasonography. Limited HRCT was obtained just before hemodialysis. Edema, crackles, and dyspnea had a poor sensitivity of 37.9%, 11.5%, and 52.6%, respectively, to detect clinically significant pulmonary congestion by lung ultrasound. A highly significant correlation was obtained between B-line score and HRCT signs of pulmonary congestion (P < 0.001) before dialysis. B lines showed statistically significant reduction with dialysis. The absolute reduction of B lines showed significant correlation with ultrafiltration volume and weight loss. Bedside lung ultrasound appears a sensitive tool for evaluating real-time changes in extravascular lung water and would serve to optimize volume status in dialysis patients.

Lung ultrasound in the assessment of hypervolemia in hemodialysis patients - two case reports

Introduction. Hemodialysis patients often have chronic volume overload, hypervolemia, which may cause severe complications. In some patients hypervolemia is masked, without any signs and symptoms, such as hypertension, edema and bibasilar crackles on lung auscultation. Lung ultrasound can be used to detect these patients. Pre- and post-dialysis lung ultrasound can be used to quantify lung congestion using the B line score. High post-dialysis B line score can identify patients with residual hypervolemia and adequate measures can be taken (increasing ultrafiltration, extended duration of hemodialysis, additional dialysis sessions). Case Reports. The first patient was a 57-year-old male. The hemodialysis vintage was 4 years. His interdialytic weight gain was 2.8 kg. The lung ultra?sound was performed before and after dialysis and B line score was calculated. The pre-dialysis score was 15 and post-dialysis score was 2. The second patient was a 72-year-old male. The hemodialysis started 5 years before. This patient was noncompliant with the medical advice of his physician regarding diet and medications. His interdialytic weight gain was 5.6 kg. His pre-dialysis score was 26 and post-dialysis score was 15. Both patients were without signs and symptoms of hypervolemia after dialysis. Nevertheless, the second patient was 1.6 kg over his dry weight after dialysis. An additional dialysis session was scheduled, after which his post-dialysis B line score fell to 5. Conclusion. Lung ultrasound can be used to assess volume status in dialysis patients. It can identify hypervolemia in asymptomatic patients and allow necessary corrections.

Predialysis NTproBNP Predicts Magnitude of Extracellular Volume Overload in Haemodialysis Patients

Introduction: Increased natriuretic peptides are associated with increased cardiovascular and all-cause mortality for haemodialysis (HD) patients. However, debate continues whether these biomarkers are increased by extracellular water (ECW) excess and can be used to aid clinical assessment of volume status and help determine target weight. Methods: We measured N terminal probrain natriuretic peptide (NT-proBNP) predialysis in 375 stable haemodialysis outpatients with corresponding pre and postdialysis multifrequency bioelectrical impedance assessments (MFBIA) of (ECW)/total body water (TBW). Results: Median age 64 (51-75), 63.9% male, 42.9% diabetic, 43.2% Caucasoid, 14.4% with a history of myocardial infarction, 8.4% coronary artery bypass surgery, dialysis vintage 28.2 (12.3-55.5) months. Median predialysis NT-proBNP 283 (123-989) pmol/l, and predialysis ECW/TBW ratio 0.397 ± 0.029. On multivariate analysis, predialysis log NT-proBNP was associated with predialysis systolic blood pressure (β 0.007, p = 0.000), weight (β −0.008, p = 0.001), valvular heart disease (β 0.342, p = 0.015, ECW/TBW (β 1.3, p = 0.019) and log CRP (β 0.145, p = 0.037). Dividing patients into NTproBNP quartiles, %ECW/TBW and relative ECW overhydration were significantly greater for the highest quartile vs. lowest (40.5 ± 4.1 vs. 39.0 ± 1.1, and 1.51 ± 1.24 vs. 0.61 ± 0.69 l, respectively, p < 0.001). Conclusion: In this study, predialysis NTproBNP values were associated with direct assessments of the extracellular volume excess measured by MFBIA and systolic arterial blood pressure. This suggests that predialysis NTproBNP values can potentially be used to aid clinical assessment of volume status in dialysis patients to determine target weight.

Is There a Role for N-Terminal Probrain-Type Natriuretic Peptide in Determining Volume Status in Haemodialysis Patients?

Background/Aims: Natriuretic peptides have been reported to be a valuable biomarker for predicting cardiac events and mortality for haemodialysis patients. However, there has been a debate as to whether these biomarkers can be used to assess volume overload and help determine dry weight. Methods: We measured the N-terminal probrain natriuretic peptide (NTproBNP) in 366 stable haemodialysis outpatients with a corresponding pre- and post-dialysis multifrequency bioimpedance assessment of extracellular water (ECW)/total body water (TBW). Results: Median age was 61 years (46–73); 58.5% were male, 28.5% diabetic, and 37.7% Caucasoid; 71.1% had a history of hypertension, 8.4% of myocardial infarction, and 9.3% of coronary artery bypass surgery; dialysis vintage was 54 months (22–85.5), and urea reduction ratio was 73.4 ± 7.6%. Median post-dialysis NTproBNP was 179 pmol/l (68–535), pre-dialysis ECW/TBW was 0.393 ± 0.014, and post-dialysis ECW/TBW was 0.385 ± 0.015. On multivariate analysis log NTproBNP was associated with post-dialysis ECW/TBW (β 9.09, 95% CI 3.22–14.95, p = 0.003), mean arterial pressure (β 0.0087, 95% CI –0.0045 to –0.013, p = 0.000), and ultrafiltration rate (ml/kg· h; β 0.038, 95% CI 0.01–0.06, p = 0.001). Conclusion: In this study postdialysis NTproBNP values were correlated with direct assessments of volume status in haemodialysis patients, i.e. by ECW/TBW, or indirect measures of volume overload, i.e. ultrafiltration rate and post-dialysis mean arterial blood pressure. This suggests that serial NTproBNP values may aid clinical assessments of volume status in dialysis patients.

Circulatory malfunction during dialysis—basic physiology

Circulatory malfunction is a common and troublesome adverse reaction to hemodialysis treatment that causes patient discomfort, influences dialysis adequacy, and is associated with increased morbidity and mortality. Hypotensive episodes may be caused by a variety of factors of which hypovolemia, owing to aggressive ultrafiltration, is the most frequent. Because the clinical evaluation of volume status in dialysis patients is fraught with uncertainties, intradialytic cardiovascular monitoring is an important tool to prevent the occurrence of hypotension. Relative blood volume sensoring, the tracking of the hematocrit change during dialysis, has become the standard method. However, widespread routine use has turned out to be helpful but not sufficient to eliminate the problem. The presentation will outline the pathophysiologic events related to hemodialysis-induced circulatory malfunction. Particular focus will be put on the role of the autonomic nervous system in the counterregulatory response to hypovolemia and how shifts in autonomic nervous activity can be exploited for electrocardiographic monitoring. The possible role for intradialytic monitoring as an aid in the determination of dry weight will be discussed.

Noninvasive quantification of blood potassium concentration from electrocardiogram analysis

Circulatory malfunction is a common and troublesome adverse reaction to hemodialysis treatment that causes patient discomfort, influences dialysis adequacy, and is associated with increased morbidity and mortality. Hypotensive episodes may be caused by a variety of factors of which hypovolemia, owing to aggressive ultrafiltration, is the most frequent. Because the clinical evaluation of volume status in dialysis patients is fraught with uncertainties, intradialytic cardiovascular monitoring is an important tool to prevent the occurrence of hypotension. Relative blood volume sensoring, the tracking of the hematocrit change during dialysis, has become the standard method. However, widespread routine use has turned out to be helpful but not sufficient to eliminate the problem. The presentation will outline the pathophysiologic events related to hemodialysis-induced circulatory malfunction. Particular focus will be put on the role of the autonomic nervous system in the counterregulatory response to hypovolemia and how shifts in autonomic nervous activity can be exploited for electrocardiographic monitoring. The possible role for intradialytic monitoring as an aid in the determination of dry weight will be discussed.

Alterations of atrial electrophysiology after hemodialysis session: a simulation study in volumetric atrial tissues

Circulatory malfunction is a common and troublesome adverse reaction to hemodialysis treatment that causes patient discomfort, influences dialysis adequacy, and is associated with increased morbidity and mortality. Hypotensive episodes may be caused by a variety of factors of which hypovolemia, owing to aggressive ultrafiltration, is the most frequent. Because the clinical evaluation of volume status in dialysis patients is fraught with uncertainties, intradialytic cardiovascular monitoring is an important tool to prevent the occurrence of hypotension. Relative blood volume sensoring, the tracking of the hematocrit change during dialysis, has become the standard method. However, widespread routine use has turned out to be helpful but not sufficient to eliminate the problem. The presentation will outline the pathophysiologic events related to hemodialysis-induced circulatory malfunction. Particular focus will be put on the role of the autonomic nervous system in the counterregulatory response to hypovolemia and how shifts in autonomic nervous activity can be exploited for electrocardiographic monitoring. The possible role for intradialytic monitoring as an aid in the determination of dry weight will be discussed.