How Would You Prescribe the Dialysate Sodium Concentration for Your Patients?

Low sodium dialysate was commonly used in the early year of hemodialysis to enhance diffusive sodium removal beyond its convective removal by ultrafiltration. However, disequilibrium syndrome was common, particularly when dialysis sessions were reduced to 4 h. The recent trend of lowering the DNa from the most common level of 140 mEq/L has been associated with intradialytic hypotension and increased risk of hospitalization and mortality. Higher DNa also has disadvantages, such as higher blood pressure and greater interdialytic weight gain, likely due to increased thirst. My assessment of the evidence leads me to choose DNa at the 140 level for most patients and to avoid DNa below 138. Patients with intradialytic symptoms may benefit from DNa 142 mEq/L, if they can avoid excessive fluid weight gains.

What Is the Optimal Dialysate Sodium Concentration?

In haemodialysis, sodium and fluid balance (where intake matches loss) is achieved by ultrafiltration and by diffusion between the plasma water and dialysate. If a patient’s sodium intake does not change, any reduction in fluid gain obtained by lowering dialysate sodium concentration will result in less sodium removal by ultrafiltration. The corresponding change in diffusion to achieve balance may mean the benefit of lower fluid gain is offset by morbidity caused by a fall in serum sodium during dialysis. The standard dialysate sodium should minimise harm caused by both high ultrafiltration rates and osmotic disequilibrium. For most units, this is likely to be 138 to 140 mmol/L.

Recovery of Alkaline Earth Metals from Desalination Brine for Carbon Capture and Sodium Removal

Because carbon dioxide adsorbs the radiation from the Sun and the Earth’s surface, global warming has become a severe problem in this century. Global warming causes many environmental problems such as heatwave, desertification, and erratic rainfall. Above all, erratic rainfall makes people have insufficient freshwater. To solve this problem, desalination technology has been developed in many countries. Although desalination technology can provide freshwater, it produces brine as well (producing 1 L of freshwater would result in 1 L of brine). The brine will decrease the dissolved oxygen in the sea and affect the organism’s habitat. In this study, magnesium and calcium from desalination brine were recovered in the form of magnesium hydroxide and calcium hydroxide by adjusting the pH value for carbon capture and sodium removal. Magnesium hydroxide would turn into magnesium carbonate through contacting CO2 in saturated amine carriers. Calcium hydroxide was added to the brine and reacted with CO2 (modified Solvay process). Sodium in brine would then be precipitated in the form of sodium bicarbonate. After removing sodium, brine can be released back into the ocean, or other valuable metals can be extracted from brine without the side effect of sodium. The results revealed that 288 K of 3-Amino-1-propanol could capture 15 L (26.9 g) of CO2 and that 25 g/L of Ca(OH)2 at 288 K was the optimal parameter to remove 7000 ppm sodium and adsorb 16 L (28.7 g) of CO2 in the modified Solvay process. In a nutshell, this research aims to simultaneously treat the issue of CO2 emission and desalination brine by combining the amines carrier method and the modified Solvay process.

Volume-Independent Sodium Toxicity in Peritoneal Dialysis: New Insights from Bench to Bed

Sodium overload is common in end-stage kidney disease (ESKD) and is associated with increased cardiovascular mortality that is traditionally considered a result of extracellular volume expansion. Recently, sodium storage was detected by Na23 magnetic resonance imaging in the interstitial tissue of the skin and other tissues. This amount of sodium is osmotically active, regulated by immune cells and the lymphatic system, escapes renal control, and, more importantly, is associated with salt-sensitive hypertension. In chronic kidney disease, the interstitial sodium storage increases as the glomerular filtration rate declines and is related to cardiovascular damage, regardless of the fluid overload. This sodium accumulation in the interstitial tissues becomes more significant in ESKD, especially in older and African American patients. The possible negative effects of interstitial sodium are still under study, though a higher sodium intake might induce abnormal structural and functional changes in the peritoneal wall. Interestingly, sodium stored in the interstial tissue is not unmodifiable, since it is removable by dialysis. Nevertheless, the sodium removal by peritoneal dialysis (PD) remains challenging, and new PD solutions are desirable. In this narrative review, we carried out an update on the pathophysiological mechanisms of volume-independent sodium toxicity and possible future strategies to improve sodium removal by PD.

Phragmites australis (Reed) as an Efficient, Eco-Friendly Adsorbent for Brackish Water Pre-Treatment in Reverse Osmosis: A Kinetic Study

A cost-effective adsorbent was prepared by carbonization of pre-treated Phragmites australis reed at 500 °C. Phragmites australis was characterized using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and Brunauer–Emmett–Teller (BET) surface analyses. XRD of the as-prepared adsorbent exhibited a partially crystalline structure with a specific surface area of 211.6 m2/g and an average pore diameter of 4.2 nm. The biosorption potential of novel biosorbent Phragmites australis reed was investigated with a batch scale and continuous flow study. The study was conducted at different constraints to obtain optimum pH conditions, adsorbent dose, contact time, agitation speed, and initial TDS concentration. In order to analyze the properties of the procedure and determine the amount of sodium removal, Langmuir, Freundlich, and Dubinin–Radushkevich isotherms were tested. The optimal values of contact time, pH, and adsorbent dose were found to be 150 min, 4, and 10 g/L, respectively, with an agitation speed of 300 rpm at room temperature (27 °C). The three tested isotherms show that the adsorption of Na+ onto the prepared adsorbent is a hybrid process from physi- and chemisorption. For industrial application, the adsorbent was tested using the adsorbent column technique. Pseudo-first-order, pseudo-second-order, and diffusion models were connected, and it was discovered that the information fit best to the pseudo-second-arrange active model. According to the intraparticle diffusion model, the mechanism goes through four stages before reaching equilibrium. The periodicity test shows that the adsorption ability of Phragmites australis can be recovered by washing with 0.1 M HCl.

Survival of Peritoneal Membrane Function on Biocompatible Dialysis Solutions in a Peritoneal Dialysis Cohort Assessed by a Novel Test

Background: Longitudinal surveillance of peritoneal membrane function is crucial in defining patients with a risk of ultrafiltration failure. Long PD is associated with increased low molecular weight solute transport and decreased ultrafiltration and free water transport. Classic PET test only provides information about low molecular solute transport, and the vast majority of longitudinal studies are based on this test and include patients using conventional dialysates. Our aim was to prospectively analyze longitudinal data on peritoneal function in patients on biocompatible solutions using a novel test. Methods: Membrane function data were collected based on uni-PET (a combination of modified and mini PET). A total of 85 patients (age 61.1 ± 15.1 years) with at least one test/year were included. Results: The median follow up was 36 months (21.3, 67.2). A total of 219 PETs were performed. One-way repeated measures ANOVA showed that there were no statistically significant differences over time in ultrafiltration, free water transport, ultrafiltration through small pores, sodium removal, D/D0 and D/PCre in repeated PET-tests. Twenty-three tests revealed ultrafiltration failure in 16 (18.8%) patients. Those patients were longer on PD, had higher D/P creatinine ratios, lower ultrafiltration at one hour with lower free water transport and higher urine volume at baseline. Multivariate analysis revealed that the variation of ultrafiltration over repeated PET-tests independently correlated only with D/Pcreatinine, free water transport and ultrafiltration through small pores. Conclusions. Uni-PET is a combination of two tests that provides more information on the function of the membrane compared with PET. Our study on a PD cohort using only biocompatible solutions revealed that function membrane parameters remained stable over a long time. Ultrafiltration failure was correlated with increased D/P creatinine and decreased free water transport and ultrafiltration through small pores.

MO717EFFECT ON BLOOD PRESSURE OF UNCOMPENSATED 130 MM SODIUM DIALYSATE IN CAPD PATIENT WITH RESISTANT HYPERTENSION

Background and Aims In peritoneal dialysis (PD) blood pressure (BP) control is largely unsatisfied mainly due to sodium retention. Currently, sodium removal in PD patients depends substantially on ultrafiltration. Lowering sodium in PD solution might improve sodium removal by diffusion, though the real benefit of low PD solution remains still undetermined. Method In this case report, we used a novel uncompensated glucose-based PD solution (DextroCore LS, Iperboreal Pharma, Italy) containing 130 mM sodium to treat resistant hypertension in 78-year-old female treated by CAPD (3 dwells glucose 1.5% a day, Na 132). Results At baseline, Ambulatory BP monitoring (ABPM) showed 24h-BP (152/81 mmHg), diurnal BP (151/83 mmHg) and nocturnal BP (153/75 mmHg), with inversion of circadian rhythm in systolic BP (systolic night/day ratio: 1.02), despite the use of three anti-hypertensive (doxazosin 4mg, amlodipine 10 mg, telmisartan 80 mg) and diuretic (furosemide 250 mg) at adequate doses. She had no signs of hypervolemia. We switched from standard PD (132 mM/L) to low sodium PD solution using 1.5% glucose bags with sodium concentration of 130 mM. CAPD schedule was confirmed. Second ABPM after six months reported a reduction 24h BP (131/73 mmHg), diurnal (134/75 mmHg) and nocturnal BP (122/67 mmHg), with restoring of circadian BP rhythm. No change in body weight, UF and residual diuresis was found. Diet and therapy prescriptions were unmodified. No side effects were reported. Conclusion Six-months PD treatment with uncompensated glucose-based PD solution containing 130 mM sodium in all daily dwells has allowed to reduce systolic BP (-16 mmHg) in a CAPD patient affected by resistant hypertension, with no change in ultrafiltration and residual diuresis.

MO687FREE WATER TRANSPORT AND ABSOLUTE DIP OF DIALYSATE SODIUM CONCENTRATION: EARLY CLINICAL PARAMETERS FOR PERITONEAL FIBROSIS IN PD PATIENTS?

Background and Aims Reduction of peritoneal salt and water removal is an important cause of shortened patient and technique survival in peritoneal dialysis (PD). The aim of this study was to longitudinally analyze changes in fluid and solute transport parameters in PD patients during the first year of treatment, using peritoneal equilibration test (PET). Method Retrospective observational study of incident PD patients who underwent 4-hour 3.86% glucose PET with additional measurement of ultrafiltration at 1 hour, 1 month after PD initiation and 12 months later. Parameters of peritoneal transport such as dialysate-to-plasma ratio of creatinine (D/Pcreat), ultrafiltration at 1 and 4 hours, small-pore ultrafiltration (SPUF), free water transport (FWT), sodium removal and absolute dip of dialysate sodium concentration (ΔDNa) at 1 hour (as an expression of sodium sieving), were calculated. Serum cancer antigen 125 (CA-125) was also assessed. Clinical, analytical and demographic data were analyzed. Statistical analysis was performed using SPSS (Version 23 for Mac OSX). Results The average age of 16 incident PD patients was 58.69 ± 8.51 years, 10 (62.5%) were male and 5 (31.8%) were diabetic. Ten patients (62.5%) were on automated peritoneal dialysis (APD). One month after PD initiation, membrane characteristics were: D/P = 0.684 ± 0.589, total UF at 4h = 0.696 ± 0.283L, UF at 1h = 0.487 ± 0.162L, SPUF = 0.303 ± 0.359L, FWT = 0.207 ± 0.738L, %FWT = 51.855 ± 11.828%, sodium removal = 38.048 ± 16.087mmol/L and ΔDNa = 11.125 ± 3.34mmol/L. Average serum CA-125 was 51.206 ± 22.6U/mL. A paired sample t-test was performed to compare these parameters 1 and 12 months after PD initiation and revealed a statistically significant increase of 0.11± 0.196L (p=0.042) on SPUF and 18.607 ± 7.1mmol/L (p=0.019) on sodium removal. ΔDNa showed a decrease of 2.5 ± 0.743mmol/L (p=0.005) and % FWT of 11.782 ± 12.831% (p=0.002). FWT also showed a decrease of 0.168 ± 0.019L, total UF at 4h of 0.206 ± 0.142L and UF at 1h of 0.114 ± 0.243L, however did not reach statistical significance. D/Pcreat remained stable. CA-125 showed a mild decrease of 3.644 ± 22.364U/mL although not statistically significant. Pearson correlation revealed a positive correlation between the variation of total UF at 4h and the variation of FWT (r=0.553, p=0.026) and ΔDNa (r=0.503, p=0.047), but not with SPUF, sodium removal, D/Pcreat or CA-125, during the study follow-up period. Conclusion The reduction of FWT through aquaporins and, particularly, the reduction of ΔDNa as a sodium sieving measure, appear to be the first functional changes in peritoneal membrane, suggesting that fibrosis may begin soon after PD initiation. Our results indicate that FWT and ΔDNa can be used to access fibrotic peritoneal alterations earlier than other conventional parameters such as D/Pcreat.