Ultrafiltration Rate Research Articles

Dyslipidemia in Peritoneal Dialysis: Implications for Peritoneal Membrane Function and Patient Outcomes.

Dyslipidemia is a common metabolic complication in patients undergoing peritoneal dialysis (PD) and has traditionally been viewed primarily in terms of cardiovascular risk. Current guidelines do not recommend initiating lipid-lowering therapy in dialysis patients due to insufficient evidence of its benefits on cardiovascular mortality. However, the impact of dyslipidemia in PD patients may extend beyond cardiovascular concerns, influencing PD-related outcomes such as the peritoneal ultrafiltration rate, residual kidney function, PD technique survival, and overall mortality. This review challenges the traditional perspective by discussing dyslipidemia's potential role in PD-related complications, which may account for the observed link between dyslipidemia and increased all-cause mortality in PD patients. It explores the pathophysiology of dyslipidemia in PD, the molecular mechanisms linking dyslipidemia to peritoneal membrane dysfunction, and summarizes clinical evidence supporting this hypothesis. In addition, this paper examines the potential for therapeutic strategies to manage dyslipidemia to improve peritoneal membrane function and patient outcomes. The review calls for future research to investigate dyslipidemia as a potential contributor to peritoneal membrane dysfunction and to develop targeted interventions for PD patients.

Frequency and risk factors of congestive heart failure in hemodialysis patients in Assiut University Hospital

Background Cardiac failure is a leading cause of death for patients with chronic kidney disease and end-stage renal disease (ESRD). This study aimed to assess the prevalence of congestive heart failure (HF) in ESRD patients and evaluate its main risk factors. This data will help to provide better care to our patients and improve the outcome. Patients and methods A descriptive observational study was carried out on 290 individuals with ESRD who were on regular hemodialysis. The patients were categorized into two groups based on cardiac failure. The first group consisted of individuals diagnosed with HF, whereas the second group included people who showed no signs of HF. Results Logistic regression analysis revealed that smoking, hemoglobin level, ultrafiltration rate, ischemic heart disease, and ejection fraction were considered independent predictors for HF ESRD patients. Conclusion Congestive HF is prevalent among people undergoing hemodialysis. The main reasons for this high occurrence included the high prevalence of cardiovascular risk factors such as diabetes and hypertension, along with complications of renal failure such as anemia.

High Ultrafiltration Rate and Mortality among Patients Undergoing Hemodiafiltration at St. Luke's Medical Center-Global City: A Retrospective Cohort Study

High Ultrafiltration Rate and Mortality among Patients Undergoing Hemodiafiltration at St. Luke's Medical Center-Global City: A Retrospective Cohort Study

A Pilot and Feasibility Study of Continuous Cardiac Output and Blood Pressure Monitoring during Intermittent Hemodialysis

Introduction: Hypotension is common during intermittent hemodialysis (IHD) and may be due to a decreased cardiac index (CI). However, no study has simultaneously and continuously measured CI and mean arterial pressure (MAP) to understand the prevalence, severity, and duration of CI decreases or relate them to MAP, blood volume (BV), and net ultrafiltration (NUF) rate. Methods: In a prospective, pilot and feasibility investigation, we studied 10 chronic IHD patients. We used the ClearSight System™ to continuously monitor CI and MAP; the CRIT-LINE®IV monitor to detect BV changes and collected data on NUF rate. Results: Device tolerance and compliance were 100%. All patients experienced at least ≥1 episode of severe CI decrease (>25% from baseline), with a median duration of 24 min (IQR 6–87) and of 68 min [14–106] for moderate decreases (>15% but ≤25% from baseline). Eight patients experienced a low CI state (<2.2 L/min/m2). The lowest CI was 0.9 L/min/m2 with a concomitant MAP of 94 mm Hg. When the fall in CI was severe, MAP increased in 58% of cases and remained stable in 28%. Overall, CI decreased by −0.55 L/min/m2 when BV decrease was moderate versus mild (p < 0.001) and by −0.8 L/min/m2 when NUF rate was high versus low (p < 0.001). Conclusion: Continuous CI monitoring is feasible in IHD and shows frequent moderate-severe CI decreases, sometimes to low CI state levels. Such decreases are typically associated with markers of decreased intravascular volume status but not with a decrease in MAP, implying marked vasoconstriction.

Intradialytic eating practices and health outcomes among hemodialysis patients, cross-sectional study

Intradialytic eating practices is a subject of debate among hemodialysis patients and is associated with a variety of clinical implications. This study aimed to investigate eating practices during hemodialysis and their influence on health outcome, including various symptoms experienced during dialysis, intradialytic hypotension, dialysis adequacy, and malnutrition. A cross-sectional study was conducted on hemodialysis patients. A structured questionnaire was used to collect information related to sociodemographic, medical history, lifestyle, dialysis, and eating practices. The occurrence of intradialytic hypotension was determined according to the patients' blood pressure measured at the beginning and end of the session, and dialysis adequacy was determined based on the ultrafiltration rate of the patients. Malnutrition was evaluated using renal inpatient screening tool (renal iNUT), and biochemical data was recruited from the patient's hospital records. A total of 260 hemodialysis patients participated in this study. The mean age was 51.29±15.92, and half of the participants were females. The findings showed no significant association between intradialytic eating practices and symptoms developed during dialysis session, intradialytic hypotension, or malnutrition (p>0.05). According to Chi-square test, a statistically significant association was found between eating practices and dialysis adequacy (p=0.037), hemoglobin level (p<0.001), and phosphorous level (p=0.003). Eating practices were not associated with symptoms that developed during dialysis sessions, intradialytic hypotension, or malnutrition, according to our findings. However, findings reveal that it is possible that eating practices may affect the adequacy of dialysis.

The effect of changes in intra-compartmental bioimpedance measurements with early intra-dialytic hypotension during haemodialysis.

Intra-dialytic hypotension (IDH) remains the commonest problem associated with routine haemodialysis treatments. Fluid shifts from intracellular(ICW) and extracellular(ECW) compartments to refill plasma volume during haemodialysis with ultrafiltration. We studied the effect of relative changes in ICW and ECW indifferent body segments using multifrequency segmental bioimpedance during haemodialysis and IDH episodes. Of 42 haemodialysis patients,16 patients (38.1%) developed IDH within the first hour of dialysis. Patients with and without early IDH were well-matched for demographics and starting bioimpedance measurements. However, after 60 min, the relative change in in ECW/ICW ratio between the non-fistula arm and leg was significantly different for the early IDH group median -1.07 (-3.33 to 0.8) versus 0.61 (-0.78 to 1.8), p < 0.05, whereas there no differences in ultrafiltration rate, relative blood volume monitoring or on-line clearance. Monitoring serial changes in fluid status in different body compartments with bioimpedance may potentially prevent IDH in the future.

Relative Blood Volume Monitoring during Continuous Renal Replacement Therapy: A Prospective Observational Study.

Hematocrit monitoring during continuous renal replacement therapy (CRRT) allows the continuous estimation of relative blood volume (RBV). This may enable early detection of intravascular volume depletion prior to clinical sequelae. We aimed to investigate the feasibility of extended RBV monitoring and its epidemiology during usual CRRT management by clinicians unaware of RBV. Moreover, we studied the association between changes in RBV and net ultrafiltration (NUF) rates. In a cohort of adult intensive care unit patients receiving CRRT, we continuously monitored hematocrit and RBV using a pre-filter noninvasive optical sensor. We analyzed temporal changes in RBV and investigated the association between RBV change and NUF rates, using the classification of NUF rates into low, moderate, or high based on predefined cut-offs. We obtained &gt;60,000 minute-by-minute measurements in &gt;1,000 CRRT hours in 36 patients. The median RBV change was negative (decrease) in 69% of patients and the median peak change in RBV was -9.3% (interquartile range: -3.9% to -14.3%). Moreover, the median RBV decreased from baseline by &gt;5% in 40.2% of measurements and by &gt;10% in 20.6% of measurements. Finally, RBV decreased significantly more when patients received a high NUF rate (&gt;1.75 mL/kg/h) compared to low or moderate NUF rates (5.32% vs. 1.93% or 1.97%, p &lt; 0.001). Continuous hematocrit and RBV monitoring during CRRT was feasible. RBV decreased significantly during CRRT, and decreases were greater with higher NUF rates. RBV monitoring may help optimize NUF management and prevent the occurrence of intravascular volume depletion.

Closed Loop Ultrafiltration Feedback Control in Hemodialysis: A Narrative Review.

While life-sustaining, hemodialysis is a non-physiological treatment modality that exerts stress on the patient, primarily due to fluid shifts during ultrafiltration. Automated feedback control systems, integrated with sensors that continuously monitor bio-signals such as blood volume, can adjust hemodialysis treatment parameters, e.g., ultrafiltration rate, in real-time. These systems hold promise to mitigate hemodynamic stress, prevent intradialytic hypotension, and improve the removal of water and electrolytes in chronic hemodialysis patients. However, robust evidence supporting their clinical application remains limited. Based on an extensive literature research, we assess feedback-controlled ultrafiltration systems that have emerged over the past three decades in comparison to conventional hemodialysis treatment. We identified 28 clinical studies. Closed loop ultrafiltration control demonstrated effectiveness in 23 of them. No adverse effects of closed loop ultrafiltration control were reported across all trials. Closed loop ultrafiltration control represents an important advancement towards more physiological hemodialysis. Its development is driven by innovations in real-time bio-signals monitoring, advancement in control theory, and artificial intelligence. We expect these innovations will lead to the prevalent adoption of ultrafiltration control in the future, provided its clinical value is substantiated in adequately randomized controlled trials.

Vascular refilling in hemodialysis using feedback-controlled ultrafiltration profile.

The rate and the duration of ultrafiltration (UF) are considered the most important factors to affect vascular refilling. The aim of the study was to investigate whether a UF profile could improve the vascular refilling. Dialysis was delivered by a machine providing feedback control of ultrafiltration rates. Absolute blood volume (BV) was measured by dialysate bolus method. Vascular refilling volume (Vref) was calculated as UF volume - Δ absolute BV. In 40 patients, refilling fraction (Vref/UF volume) was 30.5% in the first hour. Thereafter, refilling fraction steeply increased and reached maximum values in the third and fourth hour at about 95%. The cumulative refilling fraction was 68.5 ± 9.4% at the end. In 14 patients, refilling data from the feedback-controlled UF profile were compared to dialysis sessions with constant UF rates. In 12 of 14 patients, refilling fraction was significantly (p = 0.013) higher in sessions with UF profile (71.6% vs 64.4%).There was a significant negative correlation (r = -0.606; p = 0.002) between the blood volume to extracellular volume ratio and the refilling fraction. The sum of this ratio and the refilling fraction was 1.01 ± 0.06. Despite significant differences, a feedback-controlled UF profile has no advantage over the previous refilling studies with regard to the refilling fraction because vascular refilling seems to depend mainly on the ratio of BV to ECV. This would explain the different results in studies using BV guided UF feedback programs.

Does lung ultrasound-guided ultrafiltration lead to better outcomes in acute kidney injury requiring intermittent hemodialysis: A randomized control trial.

Optimization of ultrafiltration during hemodialysis is a critical parameter in achieving therapeutic efficacy and ensuring hemodynamic stability. While various modalities such as blood volume monitoring, inferior vena cava diameter assessment, natriuretic peptide levels, bioimpedance assay, and lung ultrasound have been widely explored in the context of maintenance hemodialysis, the concept of volume-guided ultrafiltration in dialysis patients with acute kidney injury remains unexplored. Adult patients with acute kidney injury requiring dialysis, who were hemodynamically stable and not on ventilator support, without underlying lung pathology or cardiac failure, were randomized into two groups. All patients underwent 28-zone lung ultrasound before dialysis. The ultrafiltration was decided based on the treating physician's clinical judgment in controls. In the intervention group, the ultrafiltration orders prescribed by the treating physician were modified, based on the Kerley B line scores obtained by lung ultrasound. The rest of the dialysis prescriptions were similar. A postdialysis lung ultrasound was done in both groups to assess the postdialysis volume status 30 min after the dialysis session. A total of 74 patients undergoing hemodialysis for acute kidney injury were randomized. The baseline characteristics were comparable except for higher baseline B line score scores in the intervention arm. All patients received similar dialysis prescriptions. The lung ultrasound-guided ultrafiltration arm had a higher change in B line scores (BLS) from baseline (4 [0-9.5] vs. 0 [0-4]; p value 0.004) during the first dialysis session. The predialysis BLS indexed to ultrafiltration (mL/kbw/h) were significantly lower in controls, reflecting a relatively higher rate of ultrafiltration in controls compared with intervention (p = 0.006). The total number of dialysis sessions done in the control and intervention arm were 61 and 59, respectively. Among controls, 23/61 sessions (37.7%) had intradialytic adverse events, whereas, in the intervention arm, only 4/59 sessions (6.7) had any adverse intradialytic events (p < 0.01). Lung ultrasound-guided ultrafiltration was associated with a better safety profile, as demonstrated by reduced intradialytic events.

Twice Weekly versus Thrice Weekly Hemodialysis-A Pilot Cross-Over Equivalence Trial.

The 2015 Update of the Kidney Disease Outcomes Quality Initiative (KDOQI) Guideline for Hemodialysis Adequacy increased the contribution of residual kidney function in calculating standard Kt/Vurea (stdKt/Vurea). However, no study has assessed the effect of prescribing twice weekly hemodialysis according to this guideline on patients' quality of life or uremic solute levels. Twenty six hemodialysis patients with average residual urea clearance (Kru) 4.7±1.8 ml/min and hemodialysis vintage of 12±15 months (range two months to 4.9 years) underwent a cross-over trial comparing four weeks of twice weekly hemodialysis and four weeks of thrice weekly hemodialysis. Twice weekly hemodialysis was prescribed to achieve stdKt/Vurea 2.2 incorporating Kru using the 2015 KDOQI Guideline. Thrice weekly hemodialysis was prescribed to achieve spKt/Vurea 1.3 regardless of Kru. Quality of life and plasma levels of secreted uremic solutes and β2 microglobulin (β2m) were assessed at the end of each period. Equivalence testing between twice and thrice weekly hemodialysis based on the Kidney Disease Quality of Life instrument (primary analysis) was inconclusive. Symptoms as assessed by the secondary outcomes Dialysis Symptom Index and post-dialysis recovery time were not worse with twice weekly hemodialysis. StdKt/Vurea was adequate during twice weekly HD (2.7±0.5), and ultrafiltration rate and plasma potassium were controlled with minimally longer treatment times (twice weekly: 195±20 vs. thrice weekly: 191±17 minutes). Plasma levels of the secreted solutes and β2m were not higher with twice weekly than thrice weekly hemodialysis. Twice weekly hemodialysis can be prescribed using the higher contribution assigned to Kru by the 2015 KDOQI Guideline. With twice weekly hemodialysis, quality of life was unchanged, and the continuous function of the residual kidneys controlled fluid gain and plasma levels of potassium and uremic solutes without substantially longer treatment times.

#91 Ultrafiltration rate induced cardiac strain (ULRICA) – study. Preliminary results of a prospective multicentre study in Sweden

Abstract Background and Aims Cardiovascular disease is the principal cause of mortality in the haemodialysis population, attributable not only to traditional risk factors but also to those specific to dialysis treatment such as fluid overload and ultrafiltration. These are modifiable risk factors. The cardiac biomarkers N-terminal pro-B-type natriuretic peptide (proBNP) and hs-Troponin T (TnT) increase during dialysis (Laveborn et al. 2012). Previous studies (Goto et al. 2023) hypothesize that this increase was related to ultrafiltration rate. The aim of the study was to determine if modifying ultrafiltration rate could reduce the elevation of these cardiac biomarkers. Method ULRICA is a multicentre study registered at ClinicalTrials.gov (NCT06153888), conducted in six centres across Sweden. It investigated the effect of ultrafiltration rate in adult, stable haemodialysis patients with a) interdialytic weight gain (IDWG) of more than 2.5% of dry body weight and b) an ultrafiltration rate of over 0.72 IDWG/h (standard UF rate). In a crossover setting each patient underwent one treatment according to standard prescription and, after one week, a second treatment with prolonged UF time to achieve an ultrafiltration rate of less than 0.6 IDWG/h or a reduction of ultrafiltration rate of at least 20% compared to standard treatment. All treatments were performed using low flux dialysers. Blood samples were collected before, after 180 min and after treatment. Levels of proBNP and TnT were then adjusted for haemoconcentration after the formula of Schneditz et al. (2012). Echocardiographic measurements were derived from echocardiographs performed within one year from study start under stable conditions. Due to the small sample size and non-normally distributed values, data were analysed using Wilcoxon signed-rank test for comparisons between treatments and Spearman's rank correlation coefficient for correlations. Results This preliminary one-centre report included 12 patients (four women, eight men) with a median age of 68.5 (range 32-86 years). There was a significant increase in TnT (p=0.008) and proBNP (p= 0.002) during dialysis with standard UF rate. The median levels of cardiac markers before treatment did not differ between the two treatments, TnT 61.5 ng/l (IQR 33.3-87.2) resp. 59.5 ng/l (IQR 35.5-90.0) and proBNP 12177.5 ng/l (IQR 3112.5-34773.0) resp. 9105 ng/l (IQR 2555.3-36803.0); (p=0.906 for TnT and p=0.638 for proBNP). The median increase of TnT was 4.1 ng/l (IQR 1.2-8.4) during standard treatment and 5.8 ng/l (IQR 0.1-10.3) during the prolonged treatment (p= 0.158). The median increase in proBNP was 3257.5 ng/l (IQR 855.0- 15074.7) during standard treatment and 2996.9 ng/l (IQR 724.1-13338.4) during the prolonged treatment (p=0.814). The changes at 180 min were also non-significant (p=0.182 for TnT and p=0.875 for proBNP). There was a positive correlation between the change in proBNP during treatment and age (R=0.85, p&amp;lt;0.001) and left ventricular mass index (LVMI) (R=0.89, p=0.019). There was also a correlation between age and LVMI (R=0.83, p=0.042). Conclusion Preliminary data of a small group of patients confirm an increase of TnT and proBNP during dialysis. Age and LVMI are strongly associated with increase of proBNP. To show whether a reduction of ultrafiltration rate per se might reduce the release of cardiac biomarkers during haemodialysis treatment, further inclusion of patients is in progress.

#500 Monitoring relative blood volume and calf bioimpedance in hemodialysis patients

Abstract Background and Aims Measurements of relative blood volume (RBV, %) are used to monitor the relative change in blood plasm during hemodialysis (HD). Continuous measurement of calf extracellular volume (cECV) during HD allows the calculation of relative change in cECV (RCE). RCE was defined as the ratio of cECV to its initial value, cECV0 (RCE = 100 × cECV/cECV0, %). The aim of our study was to investigate the relationship between RBV, RCE and the occurrence of intradialytic hypotension (IDH). Method Fifty-five HD patients were studied. We reduced the HD target weight stepwise by 0.1 to 0.2 kg per HD session until clinically defined IDH symptoms occurred. RBV was monitored using the blood volume monitor (BVM, Fresenius Medical Care, Germany). Whole body bioimpedance spectroscopy (wBIS) provided whole body ECV (wECV) and intracellular volume (wICV) pre and post HD. Continuous calf bioimpedance (Hydra 4200, Xitron Technologies, San Diego, CA USA) provided cECV during HD. Pre HD overhydration (OH) was calculated according to whole body composition model (Chamney et al, Am J Clin Nutr 2007; 85:80). Total number of HD sessions in all patients were divided into three groups according to the pre HD OH: 1) normal OH (NOH, OH &amp;lt; 1 L), 2) moderate OH (MOH, 1 ≤ OH &amp;lt; 4 L) and 3) severe OH (SOH, OH ≥ 4 L). Furthermore, patients were stratified by the presence or absence of IDH in each hydration group. Ultrafiltration rate (UFR), pre HD body weight, body mass index (BMI) were measured. Minimal RBV (RBVMin) and minimal RCE (RCEMin) in each HD session were recorded. These measures represent maximum reduction of fluid in the intravascular and interstitial spaces, respectively. Reducing cECV can be considered as refilling fluid from interstitial transferring to intravascular space driving by ultrafiltration. The difference between RCEMin and RBVMin was defined as vascular refilling capacity. Linear mixed-effect logistic regression (LMELR) analysis was applied to explore relationships between IDH with RBVMin, RCEMin, wECV and BMI. Results We studied 621 HD sessions in 55 patients. MOH was present in 57%, SOH in 22% and NOH in 21% of total number of HD sessions respectively. There were significant differences in age, UFR, RBVMin, RCEMin, pre HD wECV, BMI between three groups, while the IDH rate did not differ significantly (Table 1). RBVMin was inversely correlated with UFR (Fig. 1) in all measurements. Pre HD wECV was the only factor associated with IDH in overall measurement. Pre HD wECV was significantly lower in IDH than in non-IDH patients in the NOH group (Fig. 2). In the MOH group, UFR and RCEMin-RBVMin were higher in IDH than in non-IDH patients (Fig. 3a and Fig. 3b). In the SOH group, Pre HD OH is the major factor associated with IDH (Fig. 4). Conclusion This study found that the major factors leading to IDH are 1) lower hydration status; 2) relative higher UFR; and 3) the limited refilling capacity. RBVMin correlated with UFR, but it did not predict IDH. Combined analysis of RBV and calf bioimpedance may provide a means to quantitate the fluid transport between intravascular and interstitial compartments and could add to an early IDH warning system.

#2570 Non-invasive blood pressure monitoring in dialysis patients using pulse wave velocity

Abstract Background and Aims Dialysis patients are at high risk of circulatory dysregulation and hypotension during treatment. Intradialytic hypotension (IDH) is a potentially life-threatening complication. The main causes are high ultrafiltration volumes and high ultrafiltration rates when patients tend to gain a lot of weight between dialysis treatments. A lack of patient compliance with regard to drinking volumes and a lack of residual diuresis are risk factors for this. Close circulatory monitoring and therapy settings to avoid absolute or relatively high UF rates to prevent IDH are frequently used. These are primarily the frequent non-invasive measurement of blood pressure using cuffs, the measurement of relative blood volume and the adjustment of ultrafiltration rates to these values. Prophylactically, the dialysis time can be extended, ultrafiltration profiles or ultrafiltration breaks can be planned, the dialysate temperature can be lowered and the composition of the dialysate can be adjusted. Despite all attempts, however, the incidence of IDH in everyday clinical practice is too high. The non-invasive measurements with cuffs are not carried out frequently enough, the measurement of the relative blood volume only covers a partial range, sudden changes in vascular tension or cardiac output are not recorded. Method The pulse wave velocity (PWV) is a well-known parameter for describing the propagation of the pressure wave after ejection of the heart beat volume in the arteries. The PWV is dependent on blood pressure, vessel wall tension and cardiac output. Changes in blood pressure can therefore be recognised by measuring the PWV. With the help of a measuring device (PESAS) for the ECG signal and peripheral pulse plethysmography, PWV can be measured non-invasively, continuously, for every heartbeat and, above all, hardly noticed by the patient. The PESAS allows the time-synchronised measurement of ECG and peripheral plethysmography curves and thus the determination of PWV. It is an experimental device. We would like to present a study showing the use of a measuring device (PESAS) in 15 prevalent dialysis patients for the detection of IDH. All study participants were examined during 3 dialysis treatments. Results The measurement of PWV in chronic dialysis patients during treatment is technically feasible. The measurement is tolerated by the patients. Changes in PWV could be detected in the patients during the course of dialysis; these were also dependent on the ultrafiltration rates. Individual patient reactions to volume withdrawal varied, with both increases and decreases in PWV being demonstrated. An acute change in PWV was usually associated with a drop in blood pressure. Continuous measurement allowed IDH events to be detected earlier than intermittent blood pressure measurement with cuffs. Sudden drops in blood pressure could be detected better and earlier with the PESAS system than by measuring the relative blood volume. Conclusion The PESAS system is suitable for monitoring dialysis patients to prevent IDH. Further adjustments and optimisation of the evaluation algorithms are necessary.

#2722 Hemodialysis vascular access flow assessment by ultrasound dilution method (NephroFlow™) and ultrafiltration method with NIKKISO DBB-EXA™

Abstract Background and Aims A functioning vascular access (VA) is needed to ensure optimal dialysis. Reduced or falling levels of VA flow volume (Qa) indicate VA dysfunction and predict thrombosis. Qa can be measured by a number of different techniques, most of all using dilution techniques such as ultrasound dilution to measure the amount of recirculation induced by reversal of blood lines. The NephroFlow™ hemodialysis monitor estimates Qa using ultrasound velocity measurements of flowing blood and their dilution with 0.9% NaCl. Nikisso DBB-EXATM dialysis machine has the capacity to measure the VA recirculation rate by photometry performing a controlled rise on ultrafiltration rate; Qa is subsequently estimated using the Krivitski formula. There is little literature on the comparison of the different methodologies, but it was described that the DBB-EXATM method underestimates Qa compared to others techniques [1]. Our study aims to compare the Qa between the NephroFlow™ ultrasound dilution technique and the Nikisso DBB-EXATM ultrafiltration method. Method We performed an observational study that included 45 hemodialysis patients followed at our unit. Measurements of VA flow using the NephroFlow® device and the Nikisso-EXATM Ultrafiltration method were performed in patients with a native arteriovenous fistula or a graft. They were hemodynamically stable without acute clinical conditions. Both studies were undertaken during the first 90 minutes of a mid-week dialysis session, under a constant dialysis blood pump flow with the ultrafiltration interrupted during the procedure after having reversed the dialysis lines. For each patient we calculated the average of two Qa evaluations conducted at Nikisso-EXATM, spaced 15 days apart, with an additional evaluation using NephroFlow® conducted between these assessments. Results Forty-five patients (male: 71.1%) with a mean age of 73.2 ± 8 years were selected. The main CKD causes were diabetic kidney disease (n = 13, 28.9%) and uncertain etiology (n = 13, 28.9%). The dialysis vintage of these patients was 142.6 months (minimum 19, maximum 168). An arteriovenous fistula was present in 38 patients (84.4%) and an arteriovenous graft in 7 patients (15.6%). In the entire group, the mean flow with NephroFlow™ was 986.9 ± 515 ml/min and with DBB-EXATM 859.7 ± 522 ml/min. The measured values of the two methods presented a significant positive correlation (by Pearson) (R = 0.822, P &amp;lt; 0.01) (Fig. 1). In the group of patients with arteriovenous fistula (n = 38, 84.4%), the mean flow with NephroFlow™ was 961.8 ± 395 ml/min and with DBB-EXATM 839.1 ± 577 ml/min. The measured values of the two methods presented a significant positive correlation (by Pearson) (R = 0.844, P &amp;lt; 0.01). In the group of patients with arteriovenous graft (n = 7, 15.6%), the mean flow with NephroFlow™ was 1017.3 ± 401 ml/min and with DBB-EXATM 909.2 ± 604 ml/min. The measured values of the two methods presented a significant positive correlation (by Pearson) (R = 0.906, P &amp;lt; 0.01). Conclusion We found a significantly positive correlation between the Qa measurements obtained using both methods. The measurement of Qa using the ultrafiltration method on Nikisso DBB-EXATM seems to be a valuable and easily implementable tool for VA surveillance in both arteriovenous fistula and grafts. However, a bigger number of studies are required in this field in order to clarify this correlation with an additional comparative analysis to assess the reproducibility of measurements.

#1348 Acute kidney injury: evaluation of factors to predict the need of dialysis therapy

Abstract Background and Aims Acute kidney injury (AKI) is a clinical syndrome with heterogeneous pathophysiological mechanisms, associated with higher morbidity and mortality risk. The existing evidence shows that an episode of AKI increases the risk of chronic kidney disease and end-stage kidney disease, with considerable effects on long term outcomes. Current risk prediction scores were mostly calculated in the setting of contrast induced nephropathy and cardiac surgery reporting the patient's risk of AKI immediately before and after the invasive procedure. To date, no scoring models are available to assess the risk of progression and necessity of renal replacement therapy (RRT) for patients in the course of AKI. Method A prospective observational cohort study was conducted enrolling patients with AKI treated within the Nephrology, Dialysis and Kidney Transplant Unit of IRCCS Azienda Ospedaliero-Universitaria di Bologna from January 2022 to July 2023. The inclusion criteria were: 1) age &amp;gt;18 years, 2) stage 3 AKI according to the current KDIGO guidelines or presence of urgent RRT indication (severe hyperkalemia, metabolic acidosis or fluid overload refractory to medical treatment). The indication for RRT was given based on clinical judgement. Type of RRT, dialyzer and ultrafiltration rate were applied according to the clinical features of the patient. The primary endpoint was the association between AKI features and RRT. Secondary endpoints were evaluation of patients treated with RRT for factors associated with renal recovery. Results We studied 56 patients. The mean age ± SD was 69.8 ± 15.3 years (range, 18-94) and 37 (66.1%) were males. 18 patients (32.1%) were treated with conservative therapy and 38 (67.9%) with RRT. The factors correlated with the necessity of RRT were previous cardiovascular disease (p = 0.002), diabetes mellitus (p = 0.017), Charlson score &amp;gt;5 (p = 0.035), volume overload (p = 0.002), urine output level (p = 0.033) and C reactive protein (CRP; p = 0.020). Multivariate analysis found significant association of cardiovascular disease (OR, 5.94; 95% CI, 1.45 to 24.34; p = 0.013) and elevated CRP (OR, 1.08; 95% CI, 1.00 to 1.16; p = 0.049) during AKI episode with the RRT need in the study cohort. Higher ultrafiltration rate during RRT was correlated with non recovery of kidney function (OR, 1.86; 95% CI, 1.09 to 3.14; p = 0.021). Conclusion Cardiovascular disease and higher CRP were associated with necessity of RRT. More intensive fluid removal during RRT resulted as negative predictor of kidney function recovery. Further studies with larger study samples and randomized design are necessary to confirm these findings.

#2548 In vitro evaluation of proenkephalin kinetics in hemofiltration and hemodialysis

Abstract Background and Aims Proenkephalin A 119-159 (penKid) is a stable surrogate marker for enkephalins (endogenous opioids regulating kidney function). PenKid plasma concentration correlates to GFR and increases in AKI, for this reason it can be used for prediction and diagnosis of AKI (even subclinical forms) and need of RRT. Furthermore, it seems to be also a reliable biomarker to predict the successful liberation from RRT and may therefore aid in the successful weaning of patients from RRT. PenKid has the perk of maintaining stable its concentration during RRT, suggesting that is barely filtered, in contrast to other biomarkers. However, with its small size of 4.5 kDa, penKid can be assumed to be freely filtered through the glomerulus and dialysis membranes. To address the issue about stable penKid plasma concentrations in RRT (no extracorporeal removal or increased production in response to impaired kidney function), we planned ex vivo experiments simulating different conditions of RRT. The aim of this study is to determine the sieving coefficient and the diffusive clearance of the penKid molecule in conditions of in vitro continuous veno-venous hemofiltration (CVVH) and continuous veno-venous hemodialysis (CVVHD), respectively. Method The lyophilized peptide was solved in 20 mM Dipotassium phosphate, 6 mM Disodium EDTA [pH 8], avoiding concentrations higher than 1 mg/mL. The compound was diluted in 50 mL of plasma to ensure homogeneous distribution. For each experimental modality, a batch of blood of 1000 mL with adjusted hematocrit at 30% and albumin concentration of 3 g% was utilized. Blood was spiked with lyophilized synthetic penKid to achieve two target concentrations of 150 and 500 pmol/L in CVVH and CVVHD modalities, respectively. Blood was adjusted for a volume of 1000 mL, maintained at 37° and continuously stirred during the experiments. CVVH was performed with blood flow (QB) = 150 mL/min and ultrafiltration rate (QUF) = 20 mL/min to reproduce a filtration fraction of 20%. The ultrafiltrate was reinfused in the venous line to maintain initial volume. This allowed to define convective clearance and solute sieving coefficient in pure convective mode. CVVHD was performed with QB = 150 mL/min and dialysate flow (QD) = 35 mL/min (Net QUF = 0 mL/min). This allowed the calculation of diffusive clearance. A polysulfone dialyzer (AV1000 FMC, Bad Homburg, Germany) was utilized. Samples were taken at 10, 30, 60 minutes from the initiation of the circulation, in both modalities. Results Initial penKid concentrations in blood corresponded to the desired targets in all the experiments. Sieving coefficients displayed values between 0.69 and 1.5 and they appear to remain stable over time (Fig. 1). Diffusive clearance displayed values between 35 and 15.7 mL/min. Values appear to present a slight decrease over time (Fig. 2). The observed variability can be attributed to several factors: difference in plasma protein interference in various moments of the experiments, difference in concentration of penKid in plasma water versus plasma or blood, variability in the sample measurements. Conclusion Significant removal of penKid can be obtained by extracorporeal therapies both in convection (CVVH) and diffusion (CVVHD). Further investigation is needed to assess if these findings are confirmed during in vivo treatments in which penKid kinetics is affected by generation, elimination and changes in distribution volume.

#828 Non-invasive determination of uric acid in blood during hemodialysis with an optical spent dialysate sensor

Abstract Background and Aims Kt/V urea is conventionally used hemodialysis (HD) adequacy marker, whereas many other uremic toxins with differing removal kinetics affect the mortality of end stage kidney disease (ESKD) patients. Among them, uric acid (UA) has been shown to cause cardiovascular mortality of ESKD patients. Recently, determination of UA concentration in blood with optical sensors during HD has been attempted by Lin et al in 2021 and Żyłka et al in 2023, but the accuracy has been relatively low. Moreover, Żyłka et al measured light absorption of spent dialysate at 573 nm to determine UA concentration, whereas previous research has shown that dialysate and UA have negligible light absorption in that region. The aim of this observational study was to predict concentration of UA with higher accuracy in ESKD patients’ blood during HD with various treatment settings by monitoring spent dialysate noninvasively with an optical sensor. Method Twenty-two ESKD patients on chronic HD were included into the study. Each patient received four 4 h long midweek HD sessions: one standard HD and three haemodiafiltration (HDF) sessions with different settings. Median (interquartile range) settings of the 1 HD session were: effective blood flow (Qb) = 199 (198-199) mL/min, dialysate flow (Qd) = 297 (297-298) mL/min, ultrafiltration rate (UF) = 13 (8-16) mL/min, dialyzer area 1.5 m2 and for the 3 HDF sessions: Qb = 298 (296-356) mL/min, Qd = 788 (489-792) mL/min, substitution fluid flow (Qsubs) = 96 (66-106) mL/min, UF = 11 (8-15) mL/min, dialyzer areas 1.8 m2 and 2.2 m2. Blood samples were collected before the start and at the end of each HD session from the arterial blood line and spent dialysate samples were collected 7, 60, 120, 180 and 240 min after the start from the outlet of the HD machine. Concentration of UA in spent dialysate and serum samples were determined with HPLC. An optical sensor (Optofluid Technologies OÜ, Tallinn, Estonia) was connected to the spent dialysate outlet of the HD machine and ultraviolet (UV) light absorption of spent dialysate was measured online in real time for each HD session. A linear interactions regression model was created using light absorbance at four different UV wavelengths to predict UA concentrations in collected spent dialysate samples. A curve of UA concentration for the whole HD session was determined based on the model and UV absorbance data measured with the optical sensor. Thereafter, UA concentration in spent dialysate at the start and at the end of each session (UAsensor hereinafter) was found from the concentration curve. The data of 88 HD sessions were equally divided into calibration and validation sets. Linear regression model was created using data of calibration set to predict concentration of UA (UApredicted) in blood as follows: UApredicted = a • UAsensor • $\frac{{{\rm{Qd}} + {\rm{\ Qsubs}} + {\rm{UF\ }}}}{{{\rm{Qb}}}}$, where “a” is the slope, UAsensor is the UA concentration in spent dialysate found from the concentration curve of the optical sensor, Qb is effective blood flow and Qd+Qsubs+UF is the total flow of spent dialysate. Subsequently, the accuracy of the model was evaluated on the calibration and validation data using Bland Altman analysis. Results UA concentrations in spent dialysate determined with HPLC and estimated with the optical sensor were strongly correlated (R2 = 0.992) and with comparable accuracy (BIAS±SE) (0.1 ± 3.84) µmol/L. Coefficient of determination 0.951 with the accuracy of 0.00 ± 31.43 µmol/L was achieved for calibration group, and coefficient of determination 0.962 with the accuracy of −7.64 ± 32.06 µmol/L was achieved for validation group between the UA concentration in blood determined with HPLC and corresponding values predicted by the optical sensor, respectively (Fig. 1). Conclusion Concentration of UA in dialysate and blood can be estimated noninvasively and accurately with the optical sensor in real time. This can be used to estimate removal efficiency and levels of UA during HD. In future, removal of other uremic toxins could be additionally monitored leading to a more personalized HD treatment.

#2752 Decline of residual renal function in peritoneal patients: in search of the lost kidney?

Abstract Background and Aims The latest (2020) recommendations of the International Society of Peritoneal Dialysis have proposed a new paradigm of adequacy. In this context, preserving residual renal function (RRF) is considered one of the most important therapeutic targets to reduce cardiovascular risk and mortality. Incremental peritoneal dialysis can contribute to preserving RRF. The goal of this study is to evaluate factors which are associated with a decline in RRF in APD patients. Method We conducted a retrospective study of incidental peritoneal dialysis patients between 2020 and 2022. We started considering 62 patients who underwent APD. 23 were excluded due to lack of data, follow-up of less than 1 year, need for haemodialysis sessions before or during follow-up, interfering surgery (bariatric surgery and nephrectomy) and treatment using the CAPD technique. We analyzed data from 39 APD patients (see Table 1) and classified them into two groups based on their RRF decline using the cut-off of 1 ml/min/year (calculated as the mean of urea and creatinine clearance). They were distinguished into slow progressors and fast progressors and we identified any differences in clinical and dialysis parameters at baseline and 12-month follow-up. We calculated dialytic, renal and total Kt/V in both groups and looked for possible predictors of faster RRF loss. For statistical analysis, we used ANOVA for continuous variables, Kruskal-Wallis for non-continuous variables and Fisher for qualitative variables. Finally, predictive data were extracted using logistic regression. Results We found 22 slow progressors and 17 fast progressors. A significant difference was found in the prevalence of cardiovascular disease (18.2% vs 47.1%, p 0.028), residual renal function (5.71 ml/min vs 6.85 ml/min, p 0,03) and dialysing solution volumes (13.2 L vs 14.1 L, p 0.05) between the two groups, with higher values in the fast progressors. In this group, more male patients were also observed (p 0.11), treated with 2 or more antihypertensive drugs (p 0.30) and exposed to higher weekly dialysate glucose (p 0.23) and daily ultrafiltration rates (p 0.23). At the 12-month follow-up, the mean decline in renal function was -1, 56 ml/min in the entire sample, -3.03 ml/min in the fast progressors group and -0.43 ml/min in the slow progressors group; the change in daily Uf inversely correlated with the change in RRF (p 0.025; r -0.35, Fig. 1). There was a mean reduction in ultrafiltrate volume (-22.7 ml vs +123.5 ml, p 0.028) and in the amount of glucose in the dialysing solutions (-138.6 g vs +100.5 g, p 0.007) compared to baseline values in patients who preserved RRF. In contrast, the difference between the two groups in the number of patients who started PD with&amp;lt;5 sessions per week is borderline (p 0.099). Weekly dialysis Kt/V is higher in fast-progressor patients (1 vs 0.88; p 0.205) with a total weekly Kt/V in both cases above the recommended target of 1.7. On multivariate regression analysis, baseline renal function and the presence of heart disease correlate with a more rapid decline in RRF (p 0.047; p 0.021 respectively). Conclusion With the limitations of low sample size and short follow-up time, we observed that ultrafiltration and peritoneal exposure to dialysate glucose may play a role in RRF loss, but more research is needed to confirm this. We found that patients with heart disease and higher baseline RRF were more likely to experience a faster decline in RRF. Overall findings suggest that maintaining RRF is crucial in APD patients, and incremental dialysis can help preserve it. We recommend further studies with longer follow-up times to better understand the relationship between RRF and APD.

#1928 Stepwise incremental hemodialysis and low-protein diet supplemented with keto-analogues to preserve residual kidney function: a pilot study

Abstract Background and Aims Studies have demonstrated that chronic dialysis with residual kidney function (RKF) had better survival rates in comparison to those with diminished or absent RKF and are also further associated with improved cardiovascular outcomes. Thus, the strategic preservation of RKF following the initiation of hemodialysis or during transitional periods emerges as a crucial consideration. Compelling evidence suggests that more frequent hemodialysis may contribute to an accelerated decline in RKF, contrasting with the beneficial effects of a low-protein diet (LPD) supplemented with keto-analogues, which has been shown to delay the progression of kidney function decline in the chronic kidney disease (CKD) non-dialysis population. Our pilot study aims to investigate the impact of a stepwise incremental hemodialysis with LPD supplemented with keto-analogues approach on the preservation of RKF after the need to initiate dialysis. Method This open-label, randomized controlled trial (RCT) pilot study employed a 1:1 allocation ratio (Groups 1 and 2) and included 30 patients in CKD stage V non-dialysis, aged ≥18 years, with an eGFR of 5-10 ml/min/1.73 m² as per the CKD-EPI equation, and a urine output of ≥800 ml/day. Exclusion criteria comprised patients with active infection or inflammation, indicated by C-reactive protein (CRP) levels exceeding 10 mg/L, individuals with cancer, or those with a body mass index (BMI) ≥35 kg/m². Group 1 underwent once-weekly hemodialysis (HD) initiation lasting 4 hours, coupled with a low-protein diet (LPD) of 0.6 g/kg/day supplemented with keto-analogues (0.12 g/kg/day) on non-dialysis days and a regular protein diet (1.0 g/kg/day) on dialysis days. In contrast, Group 2 underwent twice-weekly HD initiation (4 hours each) and maintained a regular protein diet (1.0 g/kg/day) every day. A stepwise incremental approach to HD frequency (once to twice per week in Group 1 and twice to thrice per week in Group 2) was implemented if renal kidney function (RKF) fell below 3 ml/min/1.73 m², eqKt/V was ≤1.2/session, Kru was &amp;lt;3 mL/min, ultrafiltration rate exceeded 15 ml/kg/hour, serum potassium was &amp;gt;5.5 mEq/L, and serum phosphate or serum albumin were outside the ranges of &amp;gt;5.5 mg/dL and &amp;lt;3.5 g/dL, respectively. The study spanned a duration of 12 months. Results A total of 30 patients were enrolled in the study and randomized into Group 1 (N = 15) and Group 2 (N = 15). There were no significant differences in baseline characteristics, including age (58.0 ± 19.3 vs 61.9 ± 16.8 years; p = 0.638), BMI (24.0 ± 3.8 vs 23.5 ± 3.6 kg/m²; p = 0.751), eGFR (6.9 ± 1.4 vs 6.2 ± 1.9 mL/min/1.73 m²; p = 0.241), urine volume (2226 ± 729 vs 1690 ± 986 mL/day; p = 0.128), and serum albumin (3.8 ± 0.3 vs 3.6 ± 0.3 g/dL; p = 0.123). In both groups, urine volume decreased over 12 months but Group 1 exhibited significantly higher urine volumes compared to Group 2 at M6 (1697 ± 442 vs 1063 ± 480; p = 0.01), M9 (1453 ± 522 vs 918 ± 404; p = 0.02), and M12 (1119 ± 429 vs 768 ± 367; p = 0.03). Consistent with urine volume, there were significant differences in creatinine clearance (CCr) at M6 (3.9 ± 0.5 in Group 1 vs 2.7 ± 1.8 in Group 2; p = 0.05) and M9 (3.5 ± 0.3 in Group 1 vs 1.9 ± 0.9 in Group 2; p = 0.01). In Group 1, there was a need to increase the rate of dialysis to twice/week in 5 patients at average of 3.6 months after start of study. No significant differences in hospitalization, adverse effects, and patient survival were observed between the two groups. The body weight of all participant were well maintained and no sign of malnutrition. Conclusion Stepwise incremental HD initiated as once-weekly hemodialysis coupled with LPD with keto-analogue supplementation better preserved urine output and CCr compared with twice weekly HD on a regular protein diet. In a period of 12 months after initiation of dialysis, we demonstrated that this stepwise strategy was feasible.