Ultrafiltration Rate Clinical Performance Measures: Ready for Primetime?

Muscle Sodium Accumulation in Kidney Failure: Physiological Impact and Mitigation Strategies

Skeletal muscle has recently been recognized as a nonosmotic sodium reservoir that buffers dietary sodium. The in-vivo quantification of muscle sodium is based on a novel technology, sodium magnetic resonance imaging. Studies using this technology have shown that muscle sodium accumulation may be a clinical complication of chronic kidney disease (CKD). This review aims to summarize existing evidence on muscle sodium accumulation in patients with CKD and to identify knowledge gaps and topics for further research. The literature examined in this review suggests that muscle sodium accumulation is associated with CKD progression and pathological conditions. However, the causalities between muscle sodium accumulation and its related pathological changes are still elusive mainly because it is still uncertain where and how sodium accumulates in the muscle. More research is needed to address these gaps and determine if muscle sodium is a new intervention target in CKD.

Sodium First Approach, to Reset Our Mind for Improving Management of Sodium, Water, Volume and Pressure in Hemodialysis Patients, and to Reduce Cardiovascular Burden and Improve Outcomes

New physiologic findings related to sodium homeostasis and pathophysiologic associations require a new vision for sodium, fluid and blood pressure management in dialysis-dependent chronic kidney disease patients. The traditional dry weight probing approach that has prevailed for many years must be reviewed in light of these findings and enriched by availability of new tools for monitoring and handling sodium and water imbalances. A comprehensive and integrated approach is needed to improve further cardiac health in hemodialysis (HD) patients. Adequate management of sodium, water, volume and hemodynamic control of HD patients relies on a stepwise approach: the first entails assessment and monitoring of fluid status and relies on clinical judgement supported by specific tools that are online embedded in the HD machine or devices used offline; the second consists of acting on correcting fluid imbalance mainly through dialysis prescription (treatment time, active tools embedded on HD machine) but also on guidance related to diet and thirst management; the third consist of fine tuning treatment prescription to patient responses and tolerance with the support of innovative tools such as artificial intelligence and remote pervasive health trackers. It is time to come back to sodium and water imbalance as the root cause of the problem and not to act primarily on their consequences (fluid overload, hypertension) or organ damage (heart; atherosclerosis, brain). We know the problem and have the tools to assess and manage in a more precise way sodium and fluid in HD patients. We strongly call for a sodium first approach to reduce disease burden and improve cardiac health in dialysis-dependent chronic kidney disease patients.

Effects of ivabradine on the prevention of intradialytic hypotension in a dialytic patient with heart failure with reduced ejection fraction

A 65-year-old man with a history of heart failure with reduced ejection fraction (HFrEF) and renal failure was admitted due to difficulty in fluid volume control during haemodialysis. He had frequent episodes of intradialytic hypotension (IDH) with presyncope during haemodialysis despite using a vasopressor agent. Before haemodialysis, his blood pressure was 130-150/60-70 mm Hg, and his heart rate was 80-100 beats/min. There were no specific causes of IDH. For refractory IDH, he was treated with oral ivabradine (2.5 mg two times per day), which resulted in reduced heart rate and decreased occurrence of IDH. This is the first report to describe a dialysis case with HFrEF presenting with an elevated heart rate and impaired fluid management as manifested by recurring IDH, which improved after ivabradine treatment. Ivabradine therapy may assist in increasing stroke volume by lowering the sinus heart rate, thus resulting in the prevention of IDH.

Cost-effectiveness and value of information analysis of multiple frequency bioimpedance devices for fluid management in people with chronic kidney disease having dialysis

Background

Among people with chronic kidney disease (CKD) on dialysis, sub-optimal fluid management has been linked with hospitalisation, cardiovascular complications and death. This study assessed the cost-effectiveness using multiple-frequency bioimpedance guided fluid management versus standard fluid management based on clinical judgment.

Methods

A Markov model was developed to compare expected costs, outcomes and quality adjusted life years of the alternative management strategies. The relative effectiveness of the bioimpedance guided approach was informed by a systematic review of clinical trials, and focussed reviews were conducted to identify baseline event rates, costs and health state utility values for application in the model. The model was analysed probabilistically and a value of information (VOI) analysis was conducted to inform the value of conducting further research to reduce current uncertainties in the evidence base.

Results

For the base-case analysis, the incremental cost-effectiveness ratio (ICER) for bioimpedance guided fluid management versus standard management was £16,536 per QALY gained. There was a 59% chance of the ICER being below £20,000 per QALY. Form the VOI analysis, the theoretical upper bound on the value of further research was £53 million. The value of further research was highest for parameters relating to the relative effectiveness of bioimpedance guided management on final health outcomes.

Conclusions

Multiple frequency bioimpedance testing may offer a cost-effective approach to improve fluid management in patients with CKD on dialysis, but further research would be of value to reduce the current uncertainties.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12962-021-00276-6.

An update review of intradialytic hypotension: concept, risk factors, clinical implications and management

Intradialytic hypotension (IDH) is a frequent and serious complication of chronic haemodialysis, linked to adverse long-term outcomes including increased cardiovascular and all-cause mortality. IDH is the end result of the interaction between ultrafiltration rate (UFR), cardiac output and arteriolar tone. Thus excessive ultrafiltration may decrease the cardiac output, especially when compensatory mechanisms (heart rate, myocardial contractility, vascular tone and splanchnic flow shifts) fail to be optimally recruited. The repeated disruption of end-organ perfusion in IDH may lead to various adverse clinical outcomes affecting the heart, central nervous system, kidney and gastrointestinal system. Potential interventions to decrease the incidence or severity of IDH include optimization of the dialysis prescription (cool dialysate, UFR, sodium profiling and high-flux haemofiltration), interventions during the dialysis session (midodrine, mannitol, food intake, intradialytic exercise and intermittent pneumatic compression of the lower limbs) and interventions in the interdialysis period (lower interdialytic weight gain and blood pressure–lowering drugs). However, the evidence base for many of these interventions is thin and optimal prevention and management of IDH awaits further clinical investigation. Developing a consensus definition of IDH will facilitate clinical research. We review the most recent findings on risk factors, pathophysiology and management of IDH and, based on this, we call for a new consensus definition of IDH based on clinical outcomes and define a roadmap for IDH research.

Ultrafiltration Rate, Residual Kidney Function, and Survival Among Patients Treated With Reduced-Frequency Hemodialysis

RATIONALE & OBJECTIVE

Patients receiving twice-weekly or less-frequent hemodialysis (HD) may need to undergo higher ultrafiltration rates (UFRs) to maintain acceptable fluid balance. We hypothesized that higher UFRs are associated with faster decline in residual kidney function (RKF) and a higher rate of mortality.

STUDY DESIGN

Retrospective cohort study.

SETTING & PARTICIPANTS

1,524 patients with kidney failure who initiated maintenance HD at a frequency of twice or less per week for at least 6 consecutive weeks at some time between 2007 and 2011 and for whom baseline data for UFR and renal urea clearance were available.

PREDICTOR

Average UFR during the first patient-quarter during less-frequent HD (<6, 6-<10, 10-<13, and≥13mL/h/kg).

OUTCOME

Time to all-cause and cardiovascular death, slope of decline in RKF during the first year after initiation of less-frequent HD (with slopes above the median categorized as rapid decline).

ANALYTICAL APPROACH

Cox proportional hazards regression for time to death and logistic regression for the analysis of rapid decline in RKF.

RESULTS

Among 1,524 patients, higher UFR was associated with higher all-cause mortality; HRs were 1.43 (95% CI, 1.09-1.88), 1.51 (95% CI, 1.08-2.10), and 1.76 (95% CI, 1.23-2.53) for UFR of 6 to<10, 10 to<13, and≥13mL/h/kg, respectively (reference: UFR < 6mL/h/kg). Higher UFR was also associated with higher cardiovascular mortality. Baseline RKF modified the association between UFR and mortality; the association was attenuated among patients with renal urea clearance≥5mL/min/1.73m². Higher UFR had a graded association with rapid decline in RKF; ORs were 1.73 (95% CI, 1.18-2.55), 1.89 (95% CI, 1.12-3.17), and 2.75 (95% CI, 1.46-5.18) at UFRs of 6 to<10, 10 to<13, and≥13mL/h/kg, respectively (reference: UFR < 6mL/h/kg).

LIMITATIONS

Residual confounding from unobserved differences across exposure categories.

CONCLUSIONS

Higher UFR was associated with worse outcomes, including shorter survival and more rapid loss of RKF, among patients receiving regular HD treatments at a frequency of twice or less per week.

Thinking Volume First: Developing a Multifaceted Systematic Approach to Volume Management in Hemodialysis

Purpose of review:

Volume overload and hypovolemia-induced symptoms are common in the hemodialysis (HD) population and frequently result in emergency department visits and hospitalization. A structured strategy for the reporting, evaluation, and management of disordered volume status may improve clinical outcomes and the patient experience. We developed a new strategy that systematically addresses volume issues by leveraging the electronic medical record, technological adjuncts, and multidisciplinary expertise to institute new processes of care in our HD unit.

Sources of information:

This initiative was implemented in a unit located in an urban academic hospital where 250 patients receive maintenance HD. This initiative involved a multidisciplinary team of health professionals including physicians, nurse practitioners, social workers, and dieticians.

Methods:

We generated volume metrics for HD recipients based on routinely collected data from the unit’s electronic medical record. We then engaged stakeholders in a root cause analysis to identify the major causes of abnormal volume metrics locally. We subsequently developed interventions that were designed to address each of the major causes in a pragmatic and sustainable program.

Key findings:

The final product was a local volume management program with 3 components. First, we integrated volume metric reporting into the routine surveillance bloodwork reports across our unit. This enabled the clinical teams to more easily target patients at risk for volume-related adverse events and provide them with closer surveillance. Those identified with abnormal volume metrics were then evaluated with the use of technologic adjuncts such as lung ultrasound and bioimpedance spectroscopy to complement traditional assessments of volume status. Finally, those with abnormal volume metrics underwent rigorous interdisciplinary review for potential nutritional/social interventions.

Limitations:

While we report the successful initial implementation of the program within a single center, it remains unclear whether this initiative will lead to meaningful benefits for HD recipients, be readily applicable in other centers, or be sustainable in the long term.

Implications:

This volume management program will need further evaluation linked to outcome assessment and feasibility in other centers before wider adoption is advocated.

No Survival Benefit in Octogenarians and Nonagenarians with Extended Hemodialysis Treatment Time

BACKGROUND

The population of elderly end-stage renal disease patients initiating dialysis is rapidly growing. Although longer treatment is supposed to benefit for hemodialysis (HD) patients through more solute clearance and slower fluid removal, it is not yet clear how treatment session length affects mortality risk in octogenarians and nonagenarians.

METHODS

In a cohort of 112,026 incident HD patients between 2007 and 2011, we examined the association of treatment session length with all-cause mortality, adjusting for demographics and comorbid conditions. We also used restricted spline functions for age to evaluate continuous changes in the association of short (< 210 min) and extended (≥240 min) HD treatment (vs. 210 to < 240 min) with all-cause mortality over continuous age.

RESULTS

During the first 91 days of dialysis, patients aged ≥80 years tended to have the lowest treatment session length (median [interquartile range] 211 [193-230] min, r > 0.5). Longer treatment was associated with better survival in patients < 65 and 65 to < 80 years but not in octogenarians/nonagenarians. The association of extended treatment (≥240 min) with better survival was attenuated across age and not significant among patients aged ≥80 years with a hazard ratio of 1.10 (95% CI 0.99-1.20). Shorter treatment sessions (< 210 min) was associated with higher mortality across all age groups.

CONCLUSION

Extended HD was not associated with lower mortality among octogenarians and nonagenarians, while it was associated with better survival among younger patients. Further studies are needed to determine the optimal treatment session length in elderly incident HD patients.

Mechanisms, Clinical Implications, and Treatment of Intradialytic Hypotension

Individuals with ESKD requiring maintenance hemodialysis face a unique hemodynamic challenge, typically on a thrice-weekly basis. In an effort to achieve some degree of euvolemia, ultrafiltration goals often involve removal of the equivalent of an entire plasma volume. Maintenance of adequate end-organ perfusion in this setting is dependent on the institution of a variety of complex compensatory mechanisms. Unfortunately, secondary to a myriad of patient- and dialysis-related factors, this compensation often falls short and results in intradialytic hypotension. Physicians and patients have developed a greater appreciation for the breadth of adverse outcomes associated with intradialytic hypotension, including higher cardiovascular and all-cause mortality. In this review, we summarize the evidence for adverse outcomes associated with intradialytic hypotension, explore the underlying pathophysiology, and use this as a basis to introduce potential strategies for its prevention and treatment.

Ultrafiltration rate in conventional hemodialysis: Where are the limits and what are the consequences?

BACKGROUND

Ultrafiltration rate (UFR) has attracted attention as a modifiable aspect of volume management.

OBJECTIVE

The objective of this review is to summarize the evidence that links UFR to patient outcomes and discuss UFR cut-offs proposed, and discuss possible consequences of adapting UFR as a quality metric.

RESULTS

Higher UFRs has been associated with younger age, longer dialysis vintage, greater prevalence of comorbidities, higher Kt/V, lower weight, greater interdialytic weight gain, lower residual renal function, and shorter treatment times. Many of the characteristics associated with high UFRs have also been independently associated with poor patient outcomes. Four observational studies have assessed the association between UFR and patient mortality. All of them reported an association between higher UFR and greater patient mortality, though the studies differed in their definition of UFR, follow-up, and adjustment for confounding. Evidence for the association between higher UFR and potential mediations of the mortality association, such as interdialytic hypotension, cardiac remodeling, and cardiovascular events was less consistent. There was a graded association between higher UFRs and all-cause mortality; no definitive cut-off for acceptable UFR can be established based on the current evidence. Targeting UFR in isolation might result in volume expansion and worsening patient outcomes. Residual confounding likely contributed to the findings of the observational studies. No randomized controlled trials addressed the questions.

CONCLUSION

Evidence supporting UFR limits is weak and confounded. Randomized controlled trials are needed before UFR can be used as a quality of care indicator.

Hemodialysis Ultrafiltration Rate Targets Should Be Scaled to Body Surface Area Rather than to Body Weight

The association between higher ultrafiltration rates and poor outcomes in hemodialysis patients has received increased attention, to the point that various regulatory entities are considering adding ultrafiltration rate as a quality measure to be monitored and controlled. Most of the discussion to date has focused on ultrafiltration rate scaled to body weight, or more correctly, body mass (ml/hour per kg). One outcome study suggests that ultrafiltration rate might best be not scaled at all to body size, as modestly higher ultrafiltration rate in very small-size patients may be associated with some survival benefit, probably via increased dietary intake. Outcomes studies also suggest that the risk of exceeding a weight-scaled ultrafiltration target may be magnified in very large patients, and that body weight-scaled ultrafiltration targets in such patients should be set a lower level. Here, we present an analysis, based on physiological hemodynamic arguments, that it would be better to scale ultrafiltration rate to body surface area rather than to body mass. Whatever ultrafiltration rate is scaled to, attempts to restrict ultrafiltration rate by limiting interdialytic weight gain in small, possibly malnourished patients, should be done cautiously, to prevent an inadvertent lowering of intake of calories and dietary protein.

Multiple-frequency bioimpedance devices for fluid management in people with chronic kidney disease receiving dialysis: a systematic review and economic evaluation

BACKGROUND

Chronic kidney disease (CKD) is a long-term condition requiring treatment such as conservative management, kidney transplantation or dialysis. To optimise the volume of fluid removed during dialysis (to avoid underhydration or overhydration), people are assigned a 'target weight', which is commonly assessed using clinical methods, such as weight gain between dialysis sessions, pre- and post-dialysis blood pressure and patient-reported symptoms. However, these methods are not precise, and measurement devices based on bioimpedance technology are increasingly used in dialysis centres. Current evidence on the role of bioimpedance devices for fluid management in people with CKD receiving dialysis is limited.

OBJECTIVES

To evaluate the clinical effectiveness and cost-effectiveness of multiple-frequency bioimpedance devices versus standard clinical assessment for fluid management in people with CKD receiving dialysis.

DATA SOURCES

We searched major electronic databases [e.g. MEDLINE, MEDLINE In-Process & Other Non-Indexed Citations, EMBASE, Science Citation Index and Cochrane Central Register of Controlled Trials (CENTRAL)] conference abstracts and ongoing studies. There were no date restrictions. Searches were undertaken between June and October 2016.

REVIEW METHODS

Evidence was considered from randomised controlled trials (RCTs) comparing fluid management by multiple-frequency bioimpedance devices and standard clinical assessment in people receiving dialysis, and non-randomised studies evaluating the use of the devices for fluid management in people receiving dialysis. One reviewer extracted data and assessed the risk of bias of included studies. A second reviewer cross-checked the extracted data. Standard meta-analyses techniques were used to combine results from included studies. A Markov model was developed to assess the cost-effectiveness of the interventions.

RESULTS

Five RCTs (with 904 adult participants) and eight non-randomised studies (with 4915 adult participants) assessing the use of the Body Composition Monitor [(BCM) Fresenius Medical Care, Bad Homburg vor der Höhe, Germany] were included. Both absolute overhydration and relative overhydration were significantly lower in patients evaluated using BCM measurements than for those evaluated using standard clinical methods [weighted mean difference -0.44, 95% confidence interval (CI) -0.72 to -0.15, p = 0.003, I2 = 49%; and weighted mean difference -1.84, 95% CI -3.65 to -0.03; p = 0.05, I2 = 52%, respectively]. Pooled effects of bioimpedance monitoring on systolic blood pressure (SBP) (mean difference -2.46 mmHg, 95% CI -5.07 to 0.15 mmHg; p = 0.06, I2 = 0%), arterial stiffness (mean difference -1.18, 95% CI -3.14 to 0.78; p = 0.24, I2 = 92%) and mortality (hazard ratio = 0.689, 95% CI 0.23 to 2.08; p = 0.51) were not statistically significant. The economic evaluation showed that, when dialysis costs were included in the model, the probability of bioimpedance monitoring being cost-effective ranged from 13% to 26% at a willingness-to-pay threshold of £20,000 per quality-adjusted life-year gained. With dialysis costs excluded, the corresponding probabilities of cost-effectiveness ranged from 61% to 67%.

LIMITATIONS

Lack of evidence on clinically relevant outcomes, children receiving dialysis, and any multifrequency bioimpedance devices, other than the BCM.

CONCLUSIONS

BCM used in addition to clinical assessment may lower overhydration and potentially improve intermediate outcomes, such as SBP, but effects on mortality have not been demonstrated. If dialysis costs are not considered, the incremental cost-effectiveness ratio falls below £20,000, with modest effects on mortality and/or hospitalisation rates. The current findings are not generalisable to paediatric populations nor across other multifrequency bioimpedance devices.

FUTURE WORK

Services that routinely use the BCM should report clinically relevant intermediate and long-term outcomes before and after introduction of the device to extend the current evidence base.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42016041785.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Volume Balance and Intradialytic Ultrafiltration Rate in the Hemodialysis Patient

PURPOSE OF REVIEW

Volume management in hemodialysis patients is often challenging. Assessing volume status and deciding how much fluid to remove during hemodialysis, the so-called ultrafiltration rate (UFR), has remained a conundrum.

RECENT FINDINGS

To date there is no objective assessment tool to determine the needed UFR during each hemodialysis session. Higher volume overload or higher UFR is associated with poor outcomes including worse mortality and unfavorable clinical outcomes. We suggest combined use of the following criteria to determine UFR or post-dialysis target dry weight: pre-hemodialysis blood pressure and its intradialytic changes, muscle cramps, dyspnea from pulmonary vascular congestion, peripheral edema, tachycardia or palpitation, headache or lightheadedness, perspiration, and post-dialysis fatigue. Restricting fluid and salt intake-and high-dose loop diuretic use in cases of residual kidney function-can be helpful in controlling fluid gains. More frequent and more severe hypotensive episodes are associated with poor outcomes including higher death risk.

Hemodialysis Treatment Time: As Important as it Seems?

Hemodialysis treatment time and Kt/V can both be considered to be primary measures of hemodialysis adequacy, because when either goes to zero, mortality is certain in patients without residual kidney function. Treatment time is important, but it needs to be adjusted based on surface-area-normalized Kt/V, residual kidney function, and expected ultrafiltration rate. Rescaling dose of dialysis measured as Kt/V to body surface area prevents ultrashort dialysis in small patients, women, and children with minimal residual kidney function. Most if not all of the observational studies of associations between outcome and dialysis session length are probably confounded by dose targeting bias. Once adequate Kt/V (taking into account body surface area) has been provided, adequate dialysis time probably is most relevant in terms of limiting the need for a high fluid removal rate. The latter may adversely impact survival by causing recurrent ischemia to cardiovascular and other tissues. There is little high-quality evidence at this time to support a minimum 4-hour treatment time for all patients, regardless of body size, solute removal, or residual kidney function. On the other hand, there is little evidence that prolonging weekly treatment time up to 24 hours per week is harmful. The final decision regarding treatment time is best individualized, based on patient acceptability and experience, residual kidney function, body surface-area-normalized Kt/V, and expected ultrafiltration rate.