Rate Of Fluid Removal Research Articles

The effect of ultrafiltration transmembrane permeation on the flow field in a surrogate system of an artificial kidney

Abstract Renal Replacement Therapies generally associated to the Artificial Kidney (AK) are membrane-based treatments that assure the separation functions of the failing kidney in extracorporeal blood circulation. Their progress from conventional hemodialysis towards high-flux hemodialysis (HFHD) through the introduction of ultrafiltration membranes characterized by high convective permeation fluxes intensified the need of elucidating the effect of the membrane fluid removal rates on the increase of the potentially blood-traumatizing shear stresses developed adjacently to the membrane. The AK surrogate consisting of two-compartments separated by an ultrafiltration membrane is set to have water circulation in the upper chamber mimicking the blood flow rates and the membrane fluid removal rates typical of HFHD. Pressure drop mirrors the shear stresses quantification and the modification of the velocities profiles. The increase on pressure drop when comparing flows in slits with a permeable membrane and an impermeable wall is ca. 512% and 576% for $ \mathrm{CA}22/5\%{\mathrm{SiO}}_2 $ and $ \mathrm{CA}30/5\%{\mathrm{SiO}}_2 $ membranes, respectively.

Net ultrafiltration prescription survey in Europe

BackgroundFluid overload is common in patients in the intensive care unit (ICU) and ultrafiltration (UF) is frequently required. There is lack of guidance on optimal UF practice. We aimed to explore patterns of UF practice, barriers to achieving UF targets, and concerns related to UF practice among practitioners working in Europe.MethodsThis was a sub-study of an international open survey with focus on adult intensivists and nephrologists, advanced practice providers, and ICU and dialysis nurses working in Europe.ResultsFour hundred eighty-five practitioners (75% intensivists) from 31 countries completed the survey. The most common criteria for UF initiation was persistent oliguria/anuria (45.6%), followed by pulmonary edema (16.7%). Continuous renal replacement therapy was the preferred initial modality (90.0%). The median initial and maximal rate of net ultrafiltration (UFNET) prescription in hemodynamically stable patients were 149 mL/hr. (IQR 100–200) and 300 mL/hr. (IQR 201–352), respectively, compared to a median UFNET rate of 98 mL/hr. (IQR 51–108) in hemodynamically unstable patients and varied significantly between countries.Two-thirds of nurses and 15.5% of physicians reported assessing fluid balance hourly. When hemodynamic instability occurred, 70.1% of practitioners reported decreasing the rate of fluid removal, followed by starting or increasing the dose of a vasopressor (51.3%). Most respondents (90.7%) believed in early fluid removal and expressed willingness to participate in a study comparing protocol-based fluid removal versus usual care.ConclusionsThere was a significant variation in UF practice and perception among practitioners in Europe. Future research should focus on identifying the best strategies of prescribing and managing ultrafiltration in critically ill patients.

Ultrafiltration in critically ill patients treated with kidney replacement therapy.

Management of fluid overload is one of the most challenging problems in the care of critically ill patients with oliguric acute kidney injury. Various clinical practice guidelines support fluid removal using ultrafiltration during kidney replacement therapy. However, ultrafiltration is associated with considerable risks. Emerging evidence from observational studies suggests that both slow and fast rates of net fluid removal (that is, net ultrafiltration (UFNET)) during continuous kidney replacement therapy are associated with increased mortality compared with moderate UFNET rates. In addition, fast UFNET rates are associated with an increased risk of cardiac arrhythmias. Experimental studies in patients with kidney failure who were treated with intermittent haemodialysis suggest that fast UFNET rates are also associated with ischaemic injury to the heart, brain, kidney and gut. The UFNET rate should be prescribed based on patient body weight in millilitres per kilogramme per hour with close monitoring of patient haemodynamics and fluid balance. Dialysate cooling and sodium modelling may prevent haemodynamic instability and facilitate large volumes of fluid removal in patients with kidney failure who are treated with intermittent haemodialysis, but the effects of this strategy on organ injury are less well studied in critically ill patients treated with continuous kidney replacement therapy. Randomized trials are required to examine whether moderate UFNET rates are associated with a reduced risk of haemodynamic instability, organ injury and improved outcomes in critically ill patients.

Ultrafiltration rates and intradialytic hypotension: A case-control sampling of pooled haemodialysis data.

Intradialytic hypotension (IDH) is one of the most critical adverse events during maintenance haemodialysis. Previous studies reported the association of fluid removal rate with the occurrence of IDH. We aimed to identify the optimal threshold of ultrafiltration rate to prevent the occurrence of IDH events. DESIGN, PARTICIPANTSAND MEASUREMENTS: Prognostic factor research with a retrospective case-control design was conducted. Patient data were gathered from four haemodialysis units from January to December 2017. All the haemodialysis records were independently justified, whether IDH occurred or not, based on the standard definition. A total of 10 haemodialysis sessions were sampled from each patient's pool based on the incidence of events. The association of ultrafiltration rates and IDH events was explored by multivariable multilevel logistic regression. A total of 1080 haemodialysis sessions from 108 patients were included: 149 (13.8%) with IDH and 931 (86.2%) without IDH. After adjusting for all pre-specified risk factors and imbalance baselines, the odds ratio of IDH were 1.22 (95% confidence interval [CI]: 0.59, 2.52) for rate 10-12 ml/kg/h; 2.52 (95% CI: 1.20, 5.29) for rate 12-14 ml/kg/h; 4.02 (95% CI: 1.61, 10.03) for rate 14-16 ml/kg/h; and 7.41 (95% CI: 2.53, 21.68) for rate >16 ml/kg/h comparing to the referent rate of <10 ml/kg/h. The ultrafiltration rate should be limited to 12 ml/kg/h. If a higher rate of fluid removal was indicated, it should not exceed 16 ml/kg/h to avoid the occurrence of IDH.

Revisiting Filtration Fraction as an Index of the Risk of Hemofilter Clotting in Continuous Venovenous Hemofiltration.

Hemofilter clotting is a major challenge in continuous venovenous hemofiltration (CVVH). Experts recommend keeping filtration fraction, the fraction of plasma water that is removed by ultrafiltration, below 20% or 30% to avoid clotting ([1][1]). Clotting risk is believed to markedly increase when

Peritoneal Dialysis for Acute Kidney Injury Treatment in the United States: Brought to You by the COVID-19 Pandemic.

The coronavirus disease 2019 (COVID-19) pandemic has created unprecedented strain on health care resources in the United States. Initial reports of AKI rates from Wuhan, China ranged between 3% and 9%, although rates as high as 15% have been reported (1,2). For AKI requiring RRT, intermittent hemodialysis (HD) and continuous RRT (CRRT) have been mainstays of therapy in the United States. However, shortages in supplies, staffing, and available equipment among critically ill patients with COVID-19, particularly in the New York City area, have demanded alternative strategies such as acute peritoneal dialysis treatment for AKI (AKI-PD) that are being implemented. Here, we will review the rationale for the use of AKI-PD and describe potential advantages, criteria for patient selection, and practical considerations on the basis of initial experiences to consider when prescribing and delivering peritoneal dialysis (PD). PD was routine for AKI treatment worldwide well into the 1980s. However, by the 1990s with the development of the central venous catheter for HD and the advent of CRRT, PD became rarely used in higher-resource countries to treat adult patients with AKI (3). The utility and efficacy of PD to treat patients with AKI were re-examined after the publication of a series of articles from Brazil, including a randomized trial, demonstrating that PD provided acceptable care, was not inferior to daily HD in treating acutely ill patients with AKI in terms of patient mortality, and was associated with a shorter duration of AKI and need for RRT (4,5). These findings were confirmed in a randomized trial from Saudi Arabia comparing PD with hemodiafiltration (6). AKI-PD expanded dramatically in lower-resource countries with the advent of the Saving Young Lives Program in 2012, which promoted the use of PD because of minimal infrastructural requirements, including a lack of need for water …

Providing Continuous Renal Replacement Therapy in Patients on Extracorporeal Membrane Oxygenation.

A 34-year-old male was admitted for respiratory failure due to H1N1 influenza. His hypoxia worsened despite maximal ventilator support and thus initiated on venovenous extracorporeal membrane oxygenation (VV-ECMO). Whereas this stabilized his respiratory and hemodynamic status, his creatinine

Net Ultrafiltration Prescription and Practice Among Critically Ill Patients Receiving Renal Replacement Therapy: A Multinational Survey of Critical Care Practitioners.

To assess the attitudes of practitioners with respect to net ultrafiltration prescription and practice among critically ill patients with acute kidney injury treated with renal replacement therapy. Multinational internet-assisted survey. Critical care practitioners involved with 14 societies in 80 countries. Intervention: MEASUREMENT AND MAIN RESULTS:: Of 2,567 practitioners who initiated the survey, 1,569 (61.1%) completed the survey. Most practitioners were intensivists (72.7%) with a median duration of 13.2 years of practice (interquartile range, 7.2-22.0 yr). Two third of practitioners (71.0%; regional range, 55.0-95.5%) reported using continuous renal replacement therapy with a net ultrafiltration rate prescription of median 80.0 mL/hr (interquartile range, 49.0-111.0 mL/hr) for hemodynamically unstable and a maximal rate of 299.0 mL/hr (interquartile range, 200.0-365.0 mL/hr) for hemodynamically stable patients, with regional variation. Only a third of practitioners (31.5%; range, 13.7-47.8%) assessed hourly net fluid balance during continuous renal replacement therapy. Hemodynamic instability was reported in 20% (range, 20-38%) of patients and practitioners decreased the rate of fluid removal (70.3%); started or increased the dose of a vasopressor (51.5%); completely stopped fluid removal (35.8%); and administered a fluid bolus (31.6%), with significant regional variation. Compared with physicians, nurses were most likely to report patient intolerance to net ultrafiltration (73.4% vs 81.3%; p = 0.002), frequent interruptions (40.4% vs 54.5%; p < 0.001), and unavailability of trained staff (11.9% vs 15.6%; p = 0.04), whereas physicians reported unavailability of dialysis machines (14.3% vs 6.1%; p < 0.001) and costs associated with treatment as barriers (12.1% vs 3.0%; p < 0.001) with significant regional variation. Our study provides new knowledge about the presence and extent of international practice variation in net ultrafiltration. We also identified barriers and specific targets for quality improvement initiatives. Our data reflect the need for evidence-based practice guidelines for net ultrafiltration.

Net ultrafiltration rate and its impact on mortality in patients with acute kidney injury receiving continuous renal replacement therapy.

BackgroundFluid overload, a critical consequence of acute kidney injury (AKI), is associated with worse outcomes. The optimal fluid removal rate per day during continuous renal replacement therapy (CRRT) is unknown. The purpose of this study is to evaluate the impact of the ultrafiltration rate on mortality in critically ill patients with AKI receiving CRRT.MethodsThis was a retrospective cohort study where we reviewed 1398 patients with AKI who received CRRT between December 2006 and November 2015 at the Mayo Clinic, Rochester, MN, USA. The net ultrafiltration rate (UFNET) was categorized into low- and high-intensity groups (<35 and ≥35 mL/kg/day, respectively). The impact of different UFNET intensities on 30-day mortality was assessed using logistic regression after adjusting for age, sex, body mass index, fluid balance from intensive care unit (ICU) admission to CRRT initiation, Acute Physiologic Assessment and Chronic Health Evaluation III and sequential organ failure assessment scores, baseline serum creatinine, ICU day at CRRT initiation, Charlson comorbidity index, CRRT duration and need of mechanical ventilation.ResultsThe mean ± SD age was 62 ± 15 years, and 827 (59%) were male. There were 696 patients (49.7%) in the low- and 702 (50.2%) in the high-intensity group. Thirty-day mortality was 755 (54%). There were 420 (60%) deaths in the low-, and 335 (48%) in the high-intensity group (P < 0.001). UFNET ≥35 mL/kg/day remained independently associated with lower 30-day mortality (adjusted odds ratio = 0.47, 95% confidence interval 0.37–0.59; P < 0.001) compared with <35 mL/kg/day.ConclusionsMore intensive fluid removal, UFNET ≥35 mL/kg/day, among AKI patients receiving CRRT is associated with lower mortality. Future prospective studies are required to confirm this finding.

Efficacy and safety of prolonged daily hemodialysis in critically ill children weighing less than 10 kg.

Extracorporeal renal replacement therapy may be needed in those infants in whom peritoneal dialysis is not feasible or is ineffective. Prolonged daily hemodialysis (PDHD) remains the only available extracorporeal dialytic modality in children weighing less than 10 kg, in setups where continuous renal replacement therapy is unavailable and sustained low-efficiency dialysis is not feasible due to lack of dedicated HD machines capable of delivering very low dialysate flows. The use of PDHD in critically ill children weighing less than 10 kg has not received much attention. Retrospective analysis of the efficacy and safety of PDHD in critically ill children weighing less than 10 kg. Four critically ill children received a total of 49 sessions of PDHD for acute kidney injury (AKI) associated with sepsis and multiorgan dysfunction syndrome (MODS). PDHD was delivered for a duration of 6 to 8 hours daily with low ultrafiltration rates, low blood flow rates but with dialysate rates that were four times the blood flow rates, due to limitations of minimal dialysate flow rate on standard machines. The mean duration of the sessions was 6.59 ± 1.61 hours. Mean hourly ultrafiltrate (UF) rate during the sessions was 9.28 ± 2.57/kg/hour with mean patient fluid removal rate of 5.4 ± 2.56 mL/kg/hour. Predialysis serum creatinine decreased to 30% of the starting value by the fourth hemodialysis (HD) session. Thirty-three (67.4%) sessions were heparin free. Intradialytic hypotension occurred in 10 (20.4%) sessions. Premature termination of the session occurred in six (12.4%), due to hypotension in two and filter clotting in four. Hypokalemia was seen in 12 (24.4%) and hypophosphatemia in 6 (12.24%). All four patients survived. On follow-up, three are dialysis free and one is on maintenance hemodialysis. PDHD is effective and safe in critically ill small children.

Ultrafiltration-profiled hemodialysis to reduce dialysis-related cardiovascular stress: Study protocol for a randomized controlled trial

Rapid fluid removal (ultrafiltration, UF) is associated with higher cardiovascular morbidity and mortality among individuals receiving maintenance hemodialysis (HD). Fluid removal rates that exceed vascular refill rates can result in hemodynamic instability, end-organ damage to the heart, kidneys, gut and brain, among other organs, and patient symptoms. There are no known evidence-based HD treatment strategies to reduce harm from higher UF rates. Ultrafiltration profiling, the practice of varying UF rates to maximize fluid removal during periods of greatest hydration and plasma oncotic pressure, has been proposed as an HD treatment intervention that may reduce UF rate-related complications. This study is a randomized 4-phase cross-over trial in which participants are successively alternated between study arms with intervening washout periods, and treatment order is randomized. After 4-week screening and 6-week baseline periods, participants are randomized to HD with conventional UF or HD with UF profiling for a period of 3 weeks followed by a 1-week washout period before crossing over. Participants cross into conventional UF and UF profiling phases twice (2 phases per arm). The primary outcomes of interest are intradialytic hypotension (nadir intradialytic systolic blood pressure <90 mmHg), pre-to post-HD change in troponin T (expressed as a percentage), change in left ventricular global longitudinal strain (an echocardiographic measure of left ventricular systolic function), and development of intradialytic left ventricular stunning (worsening of contractile function in ≥2 segments). This study will determine the impact of UF profiling on UF rate-related cardiovascular complications in prevalent, maintenance HD patients.

A feedback system that combines monitoring of systolic blood pressure and relative blood volume in order to prevent hypotensive episodes during dialysis

Hypotensive Episodes (HEs) are one of the most common complications during dialysis. Occurrence of HEs can be reduced by applying physiological closed loop systems that monitor physiological parameter(s) and adjust dialysis related parameter(s). We developed a physiological closed loop control system (PCLCS) that monitors systolic blood pressure (sysBP) and relative blood volume (RBV) and calculates the net fluid removal (nfr) rate during dialysis. The performance of PCLCS was compared in the laboratory to a feedback system that monitors only RBV (BVFS). A laboratory test setup was developed to test the feedback systems. The test setup simulates nfr-rate and refilling of a patient’s intravascular fluid. We studied the impact of the feedback systems PCLCS and BVFS on the number of HEs (sysBP < 90 mmHg), on the variance of sysBP and RBV, on pre to post sysBP and RBV and on the achievement of the nfr-volume. PCLCS allowed 80% less HEs than BVFS (p < 0.001). Variance of sysBP and RBV were reduced by 41.8% and by 52% (p < 0.001), respectively, when using PCLCS. There were no differences between pre to post sysBP nor between pre to post RBV when comparing PCLCS to BVFS. The nfr-volume was achieved by both feedback systems.

The effect of gender on survival for hemodialysis patients: Why don't women live longer than men?

Women in the general population have a survival advantage over men, but this advantage is not sustained in end-stage kidney disease (ESKD) patients treated by hemodialysis. To understand why gender may affect survival we need to understand confounders which may affect dialysis practices. The current paradigm is to prescribe hemodialysis to achieve a target dialyzer urea clearance adjusted to total body water volume (Kt/Vurea ). Estimated glomerular filtration calculated from serum creatinine is often used to determine when patients start dialysis; as creatinine generation rates are lower in women, this may potentially result in a lead time bias with male patients starting dialysis earlier than females. When hemodialysis dose is scaled to total body water (Kt/Vurea ) women receive shorter dialysis session times. Scaling dialysis for body surface area may be more appropriate since urea generation (a surrogate for uremic toxin production) depends upon resting energy expenditure (ie, cellular metabolism) which reflects internal organ sizes. Resting energy expenditure is proportionally greater for smaller people. Women are generally smaller than men and as such have smaller sized internal organs. However, when comparing individuals, then internal organ size is best adjusted for using body surface area, not body water. The shorter, resultant dialysis session also results in lower middle molecule clearances, increases fluid removal rates and the risk of intra-dialytic hypotension; the latter potentially results in earlier loss of residual renal function. Observational studies report that the association between survival and dialyzer Kt/Vurea is improved after adjustment for body surface area, or energy expenditure. These studies also demonstrated that the conventional prescription of hemodialysis based on current Kt/Vurea targets leads to less treatment delivered to women. These multiple consequences of the generally smaller size of women compared with men may account for the unexpectedly higher relative mortality for women. As such, prospective studies investigating alternative scaling parameters are required to confirm that increasing dialysis treatments for women improves survival.

Intradialytic hypotension and splanchnic shifting: Integrating an overlooked mechanism with the detection of ischemia-related signals during hemodialysis.

In the most simple analysis, a patient's hematocrit during hemodialysis will rise when the rate of ultrafiltration exceeds the rate at which the fluid is mobilized from extravascular spaces; the greater the rise in hematocrit, the lower blood volume is and the more likely intradialytic hypotension (IDH) is to occur. A secondary mechanism of IDH may be due to sudden shift of blood volume away from the heart under conditions of borderline cardiac filling. A substantial portion of blood volume resides in the splanchnic venous system. During the early part of dialysis, a centripetal shift of red cells from this anatomical region to the central circulation has been documented to occur. The magnitude of this shift is unpredictable, and it may depend on the level of splanchnic vasoconstriction predialysis. The amount of splanchnic shift may also be reduced in patients with autonomic dysfunction. Once this central shift in blood volume has occurred, it can be reversed during further ultrafiltration due to ischemia-induced release of vasodilatory molecules that cause dilation of upstream splanchnic arterioles; this causes increased transmission of arterial pressure to the splanchnic veins, acutely increasing their capacity. The increased splanchnic venous capacity may cause a sudden shift of blood away from the central circulation to fill these veins under conditions where cardiac filling has already been reduced. The result can be severe IDH due to insufficient cardiac filling and cardiac output. One fruitful preventive approach might be to continuously monitor the blood or dialysate for the sudden appearance of such ischemia-related molecules or other signals which may herald not only dialysis hypotension but tissue stunning, warning that the fluid removal rate should be immediately reduced.

Ultrafiltration in Acute Heart Failure.

Congestion is the predominant cause of more than 1 million annual heart failure hospitalisations and recurrent fluid overload predicts poor outcomes. Unresolved congestion trumps serum creatinine increases in predicting adverse heart failure outcomes. No pharmacological approach for acute heart failure has reduced these deleterious consequences. Simplified ultrafiltration devices permit fluid removal in lower acuity hospital settings, but results regarding safety and efficacy have been variable. However, adjustment of ultrafiltration rates to patients’ vital signs and renal function has been associated with more effective decongestion and fewer heart failure events. Many aspects of ultrafiltration, including patient selection, fluid removal rates, venous access, prevention of therapy-related complications and costs, require further investigation.

HIGH SENSITIVITY TROPONIN AND BRAIN-TYPE NATRIURETIC PEPTIDE FLUCTUATION DURING HEMODIALYSIS AND THEIR POTENTIAL CLINICAL APPLICATION ON CARDIOVASCULAR PROGNOSIS

Chronic elevation of high sensitivity troponin (hs-cTnT) and Brain-type natriuretic peptide (Nt-pro-BNP) in end-stage renal disease is associated with worse cardiovascular outcomes, including in hemodialysis (HD) setting. Studies have attempted to correlate variation of those biomarkers over time to cardiovascular prognosis but little is known about how HD parameters acutely influence those biomarkers. To determine the relationship between Nt-pro-BNP and hs-cTnT with HD parameters, 50 participants that were on HD for at least a month were enrolled on the HD ward at our institution. Exclusion criteria were designed to exclude any potential alternative source of hs-cTnT and Nt-pro-BNP elevation (eg. recent myocardial infarction or heart failure, Ejection fraction < 40% (…) ). Among those approached, eight patients were excluded. Six consecutive serum samples were analysed for hs-cTnT and Nt-pro-BNP before and after HD. Hs-cTnT and Nt-pro-BNP percentage decrease after HD were individually analysed in respect with HD weight reduction percentage, ultrafiltration rate, Kt/V (HD adequacy parameter) presence of diastolic dysfunction, indexed left ventricular mass, peri-dialysis hypotension, blood filtration rate and with the other biomarker. Linear regression analysis was used in a fixed-effect model for multivariate assessment and pearson coefficient was calculated for association between the variation of the two biomarkers. Mean decrease after dialysis for hs-cTnT was 38,3% ± 3,9% and for Nt-pro-BNP was 56,1% ± 3,5%. Pearson’s correlation coefficient was of 0,646 (p<0.001) between the decrease of Hs-cTnT and Nt-pro-BNP. Nt-pro-BNP percentage fluctuated with a R2 coefficient of 0,53 with our model. Standardised significant β coefficient were the following: troponin percentage decrease: 0,570 (p<0,001), ultrafiltration rate: -0,558 (p=0,001), weight decrease percentage: 0,399 (p=0,020). Mean absolute and average changes of the two biomarkers following each HD session is shown in table 1. Hs-cTnT and Nt-pro-BNP are diminished after HD in a manner that is reproducible for the same patient and their change is interrelated. Factors that decrease Nt-pro-BNP are higher quantity of fluid removal during HD and lower ultrafiltration rates. Since elevated levels of those biomarkers correlate with increased mortality, strategies to decrease their level by adjusting hemodialysis parameters (increasing fluid removal and lowering ultrafiltration rate) could be evaluated in further studies to improve cardiovascular prognosis in patients undergoing HD.

Changes in Total Protein Concentration Due to Fluid Removal During and Shortly after Hemodialysis

Background: Changes in plasma volume during hemodialysis are complex and have been shown to depend on the rate of fluid removal and the degree of fluid overload. We examined changes in total protein concentration during and shortly after a dialysis treatment in archived data from the HEMO study. Methods: During follow-up months 4 and 36 of the HEMO study, additional blood samples were obtained during a typical dialysis session at 30 and 60 min after dialysis. In 315 studies from 282 patients where complete data were available, we calculated the concentration change in total protein and compared it to the modeled change in both total body water and extracellular fluid space as derived from 2-pool urea kinetic modeling. Results: The mean postdialysis modeled urea volume (V) was 31.1 ± 6.18 L. Mean fluid removal was 2.76 ± 1.27 kg, over a session length of 207 ± 28 min. The ratio of predialysis V to postdialysis V averaged 1.090 ± 0.040. The mean TP ratios (post/pre) at 0, 30, and 60 min postdialysis averaged 1.121 ± 0.070 (SD), 1.091 ± 0.090, and 1.091 ± 0.086. The dialysate to serum sodium gradient, studied in a different group of treatments where this information was available, had no impact on these findings, nor did the length of the interdialytic interval. Conclusions: On average, after equilibration, the change in plasma volume due to fluid removal is similar to the modeled change in total body water (urea space), irrespective of dialysate to serum sodium gradient. This supports previous observations that during dialysis with ultrafiltration, plasma volume contracts to a lesser degree than the interstitial volume and that some fluid may be removed from spaces other than the extracellular fluid.

Randomized Crossover Trial of Blood Volume Monitoring-Guided Ultrafiltration Biofeedback to Reduce Intradialytic Hypotensive Episodes with Hemodialysis.

Intradialytic hypotension (IDH) is associated with morbidity. The effect of blood volume-guided ultrafiltration biofeedback, which automatically adjusts fluid removal rate on the basis of blood volume parameters, on the reduction of IDH was tested in a randomized crossover trial. We performed a 22-week, single blind, randomized crossover trial in patients receiving maintenance hemodialysis who had >30% of sessions complicated by symptomatic IDH in five centers in Calgary, Alberta, Canada. Participants underwent a 4-week run-in period to standardize dialysis prescription and dry weight on the basis of clinical examination. Those meeting inclusion criteria were randomized to best clinical practice hemodialysis (control) or best clinical practice plus blood volume-guided ultrafiltration biofeedback (intervention) for 8 weeks, followed by a 2-week washout and subsequent crossover for a second 8-week phase. The primary outcome was rate of symptomatic IDH. Thirty-five participants entered, 32 were randomized, and 26 completed the study. The rate of symptomatic IDH with biofeedback was 0.10/h (95% confidence interval, 0.06 to 0.14) and 0.07/h (95% confidence interval, 0.05 to 0.10) during control (P=0.29). There were no differences in the rate or proportion of sessions with asymptomatic IDH or symptoms alone. Results remained consistent when adjusted for randomization order and study week. There were no differences between intervention and control in the last study week in interdialytic weight gain (difference [SD], -0.02 [0.8] kg), brain natriuretic peptide (1460 [19,052] ng/L), cardiac troponins (3 [86] ng/L), extracellular water-to-intracellular water ratio (0.05 [0.33]), ultrafiltration rate (1.1 [7.0] ml/kg per hour), and dialysis recovery time (0.43 [19.25] hours). The use of blood volume monitoring-guided ultrafiltration biofeedback in patients prone to IDH did not reduce the rate of symptomatic IDH events.

Even a Moderate Fluid Removal Rate during Individualised Haemodialysis Session Times Is Associated with Decreased Patient Survival

Background: Several studies report that fluid removal rate (FRR) above 10-13 mL/h/kg is associated with increased mortality in haemodialysis (HD) patients. Aim: The aims of this study are to assess the influence of moderate FRR on survival in a cohort of prevalent dialysis patients with various dialysis session times and to challenge the FRR thresholds associated with increased mortality risk reported previously. Methods: Interdialytic weight gain (IDWG) and FRR (calculated from ultrafiltration [UF], target weight, and session time prescriptions) were studied in 190 prevalent dialysis patients (female: 42%, mean age: 69.5 years, median vintage: 40.2 months, diabetes: 34.7%, loop diuretic prescription: 5.8%) and averaged during the final quarter of 2010. Patient survival was analysed using Kaplan-Meier and Cox-multivariate analyses. Results: The median IDWG, median session time, and median FRR were 2.33 kg (-0.54-4.57), 5.0 h (3.9-8.0 h), 6.8 mL/h/kg (1.3-16.7), respectively, and FRR was ≥10 mL/h/kg in 11.6% of the patients. The Kaplan-Meier analysis showed decreased patient survival when the FRR was above the median (6.8 mL/h/kg; p = 0.012). The FRR was found to be independently associated with increased mortality (hazard ratio 1.15 [95% CI 1.02-1.29]; p = 0.027) using stepwise Cox proportional hazard regression analysis, including age, vintage, gender, body mass index (BMI), serum albumin level, β2-microglobulin level, cardiovascular and diabetes history, and session time. Online haemodiafiltration did not change this result. The role of residual renal function was unlikely because 74% of the patients had a vintage of >18 months, a minority (5.8%) were prescribed loop diuretics (a surrogate of significant urine output) and β2-microglobulin level was not different in patients who were below or above the FRR median. Conclusion: We concluded that the FRR threshold above which there is an increased mortality is lower than what has been reported (7.8 mL/h/kg). It raises the question of the hazard of fluid removal and intermittence of standard HD.

Membrane pressures predict clotting of pediatric continuous renal replacement therapy circuits

Clotting of continuous renal replacement therapy (CRRT) circuits leads to inadequate clearance, decreased ultrafiltration, and increased resource use. We identified factors associated with premature clotting of circuits during CRRT in children. In a retrospective cohort of 26 children (median age 11.8years) receiving 79 CRRT circuits (51 heparin, 22 citrate, 6 using no anticoagulation), we captured hourly pressure, flow, and fluid removal rates along with all activated clotting time (ACT) and circuit ionized calcium measurements. Cox and logistic regression models were used to examine factors associated with premature circuit clotting before the scheduled 3-day circuit change. Of the 79 circuits, 51 (64.6%) underwent unplanned filter change due to filter clotting (median duration 18.25h, interquartile range [IQR] 9.25, 33.5h), and 28 (35.4%) underwent scheduled change (median duration 66h, IQR 61.00, 69.00h). Patient age, catheter size and location, blood flow rate, and the percentage of pre-filter replacement fluid were not associated with premature clotting. Heparin circuits were less likely than citrate circuits to clot prematurely. Each 1-mmHg increase in the transmembrane or filter pressure was independently associated with a 1.5% (95% confidence interval [CI] 1.0-2.0%) and 1.5% (95% CI 1.0-2.0%) higher risk of clotting, respectively. Higher ACTs were associated with lower transmembrane (p = 0.03) and filter (p < 0.001) pressures. The majority of circuits in our cohort were subject to unplanned filter changes. Elevated transmembrane and filter pressures were associated with clotting. Our results suggest that maintaining higher ACT may decrease the risk of circuit clotting. Larger studies are needed to examine other factors that may prolong the lifespan of the CRRT circuit in this high-risk population.