What Is the Optimal Sodium Concentration in the Dialysate?

Based on our experience in our hemodiafiltration unit we would recommend a personalized isonatremic dialysate bath. We currently prescribe 137 meq (isonatremic) or delta dialysate Na/serum Na less than 2 meq. In addition to the sodium prescribed in the dialysate, for the majority of our patients we do not restrict dietary sodium or water intake. The average sodium intake is 2775 mg per day and blood pressure is maintained without hypertensive medications. We acknowledge that part of the success for achieving dry weight may not be attributable only to the dialysate sodium but is likely the result of a combination of multiple factors such as convection therapy, cooling of dialysate, close monitoring of volume status during sessions with relative blood volume, presence of a nephrologist during all sessions and assessing volume status regularly with lung ultrasound and bioimpedance. In our experience, exercising during hemodialysis has additionally been associated with better hemodynamic status and less intradialytic hypotension. Moreover, we acknowledge there is little evidence to support a gradient dialysate to serum sodium of less than 2 meq and that our approach may not be optimal.

Real-time prediction of intradialytic relative blood volume: a proof-of-concept for integrated cloud computing infrastructure

Background Inadequate refilling from extravascular compartments during hemodialysis can lead to intradialytic symptoms, such as hypotension, nausea, vomiting, and cramping/myalgia. Relative blood volume (RBV) plays an important role in adapting the ultrafiltration rate which in turn has a positive effect on intradialytic symptoms. It has been clinically challenging to identify changes RBV in real time to proactively intervene and reduce potential negative consequences of volume depletion. Leveraging advanced technologies to process large volumes of dialysis and machine data in real time and developing prediction models using machine learning (ML) is critical in identifying these signals. Method We conducted a proof-of-concept analysis to retrospectively assess near real-time dialysis treatment data from in-center patients in six clinics using Optical Sensing Device (OSD), during December 2018 to August 2019. The goal of this analysis was to use real-time OSD data to predict if a patient’s relative blood volume (RBV) decreases at a rate of at least − 6.5 % per hour within the next 15 min during a dialysis treatment, based on 10-second windows of data in the previous 15 min. A dashboard application was constructed to demonstrate how reporting structures may be developed to alert clinicians in real time of at-risk cases. Data was derived from three sources: (1) OSDs, (2) hemodialysis machines, and (3) patient electronic health records. Results Treatment data from 616 in-center dialysis patients in the six clinics was curated into a big data store and fed into a Machine Learning (ML) model developed and deployed within the cloud. The threshold for classifying observations as positive or negative was set at 0.08. Precision for the model at this threshold was 0.33 and recall was 0.94. The area under the receiver operating curve (AUROC) for the ML model was 0.89 using test data. Conclusions The findings from our proof-of concept analysis demonstrate the design of a cloud-based framework that can be used for making real-time predictions of events during dialysis treatments. Making real-time predictions has the potential to assist clinicians at the point of care during hemodialysis.

MRI based physiological parameters are biomarkers of tumor and non tumor tissue response following radiation to brain metastases

We sought to determine the utility of early relative blood volume (rCBV), relative blood flow (rCBF) and permeability (K2 trans) measurements as biomarkers of radiation response or progression for brain metastases and to characterize early normal tissue changes following stereotactic radiosurgery. Patients were imaged with dynamic susceptibility and dynamic contrast enhanced magnetic resonance imaging at baseline, 1 week and 1 month post-treatment. Tumors outcomes were stratified using volumetric data obtained from structural images. K2trans at 1 week and rCBV at 1 month were identified as predictors of tumor response and progressive disease respectively. Pre-treatment localized dose planning CT images with overlaid isodose distributions outside the tumor were evaluated within all tissue, and segmented gray and white matter. rCBV and rCBF ratio differences between baseline, 1 week and 1 month were compared. Subsequent analysis identified increases in rCBF and rCBV ratios occurring in a dose, tissue, and time specific manner.

MRI based physiological parameters are biomarkers of tumor and non tumor tissue response following radiation to brain metastases

We sought to determine the utility of early relative blood volume (rCBV), relative blood flow (rCBF) and permeability (K2 trans) measurements as biomarkers of radiation response or progression for brain metastases and to characterize early normal tissue changes following stereotactic radiosurgery. Patients were imaged with dynamic susceptibility and dynamic contrast enhanced magnetic resonance imaging at baseline, 1 week and 1 month post-treatment. Tumors outcomes were stratified using volumetric data obtained from structural images. K2trans at 1 week and rCBV at 1 month were identified as predictors of tumor response and progressive disease respectively. Pre-treatment localized dose planning CT images with overlaid isodose distributions outside the tumor were evaluated within all tissue, and segmented gray and white matter. rCBV and rCBF ratio differences between baseline, 1 week and 1 month were compared. Subsequent analysis identified increases in rCBF and rCBV ratios occurring in a dose, tissue, and time specific manner.

FC 095INCREASED VASCULAR REFILLING BY FEEDBACK-CONTROLLED ULTRAFILTRATION PROFILE

Background and Aims Refilling volume has not been a measurable parameter in clinical practice so far, as knowing the absolute blood volume (BV) is a prerequisite. Recently, we developed a method to determine absolute BV, thus enabling quantification and comparison of the refilling volume under various conditions. In this study, we evaluated refilling with a constant UF rate and with a feedback-controlled UF profile. Method Forty dialysis patients were included and studied during their routine dialysis sessions. Absolute BV was determined by indicator dilution. Immediately at the beginning of the dialysis session (before UF was started), an on-line infusate bolus of 240 mL was injected into the venous blood line by pressing a button on the keypad of the dialysis machine 5008 (FMC). The resulting increase in relative blood volume before and after bolus administration (RBVpost-RBVpre) was used to calculate absolute BV: absolute BV (in mL) = bolus volume (240 mL) x 100 / increase in RBV (in %) Absolute BV at the end of dialysis was calculated as: absolute BVend = absolute BVbeginning x RBVend in % / 100 Refilling volume was calculated as: refilling volume = UF volume – (absolute BV beginning – absolute BV end) The refilling fraction is given as: Refilling fraction = refilling volume / UF volume UF was either set as constant UF rate or as UF profile. In contrast to the constant UF rate, the UF program integrated in the dialysis machine 5008 initially starts with twice the average UF rate. If half of the prescribed UF target is reached, the control program keeps UF and refilling in balance. Results Refilling data of 40 dialysis sessions with constant UF were compared to 40 sessions with the feedback-controlled UF profile. Refilling volumes were 1.72 ± 0.76 l during the profiled sessions and 1.60 ± 0.64 l in sessions with constant UF rate (p < 0.001, Wilcoxon test). UF volumes were similar in both treatments (2.20 ± 0.90 and 2.26 ± 0.81 L, respectively). There was a strong correlation between refilling volume and UF volume in both treatments (r = 0.98 with profile, and r = 0.92 with constant UF rate, respectively). The refilling fraction was significantly higher (p < 0.001, t-test) with the feedback-controlled UF profile (77.2 ± 8.5%) than with a constant UF rate (70.4 ± 9.9%). In one patient there was a higher refilling fraction with constant UF rate (p < 0.0001). Symptomatic hypotension occurred in 3 patients, all in sessions with constant UF rate. Refilling was not lower in these 3 cases. Conclusion Refilling volume predominantly depended on UF volume. The refilling was improved by a high UF rate at the beginning of dialysis. This confirms previous data that initially high UF rates induce the refilling sooner, and, therefore, the refilling volume is higher with the same UF. An increased UF rate at the beginning can improve volume management in haemodialysis patients. With a UF profile, more volume can be removed while maintaining a stable absolute BV which may prevent hypotension in some cases. We therefore recommend that such UF profiles should be used more often in routine clinical practice. However, with every litre of UF volume, BV is reduced by more than 200 ml, at a constant UF rate even by approximately 300 ml. This must be taken into account when prescribing the UF volume.

Low-Intensity Intradialytic Exercise Attenuates the Relative Blood Volume Drop Due to Intravascular Volume Loss during Hemodiafiltration

<b><i>Introduction:</i></b> Patients in hemodiafiltration (HDF) eliminate volume overload by ultrafiltration. Vascular volume loss is among the main mechanisms contributing to adverse events such as intradialytic hypotension. Here, we hypothesize that the intradialytic exercise (IDEX) is an intervention that could improve the acute response of physiological mechanisms involved during vascular volume loss. To test this hypothesis, we evaluated the hemodynamic response to mild aerobic exercise during HDF. <b><i>Methods:</i></b> Nineteen end-stage renal disease (ESRD) patients (11 women: 40 ± 10.8 years old, and 8 men: 42 ± 21 years old) receiving HDF thrice a week, with 6 months of previous physical conditioning, participated in this study. Three HDF sessions were scheduled for each patient: 1 resting in supine position, 1 resting in sitting position, and 1 doing aerobic exercise. The first 2 sessions were taken as control. The ultrafiltration rate was set to 800 mL/h in each session. The hemodynamic response was monitored through the relative blood volume (RBV), and cardiovascular variables measured noninvasively by photoplethysmography. Adequacy variables such as Kt/V and percentage reduction of urate, urea, creatinine (Cr), and phosphate were also monitored. <b><i>Findings:</i></b> The decrease rate of the RBV was smaller in the session with IDEX compared to the sessions with no exercise. No differences were found neither in the cardiovascular variables nor in the adequacy variables among the 3 sessions. There were no hypotension events during the session with exercise, and 8 events during the sessions without exercise (<i>p</i> = 0.002). <b><i>Discussion:</i></b> Mild exercise during HDF decreased the RBV drop and was associated with less hypotension events. The lack of differences in the hemodynamic variables suggests an adequate acute response of cardiovascular compensation variables to intradialytic hypovolemia.