Low Potassium Dialysate as a Protective Factor of Sudden Cardiac Death in Hemodialysis Patients with Hyperkalemia

Hyperkalaemia prevalence and dialysis patterns in Chinese patients on haemodialysis: an interim analysis of a prospective cohort study (PRECEDE-K)

BACKGROUND

Hyperkalaemia is a known risk factor for cardiac arrhythmia and mortality in patients on haemodialysis. Despite standard adequate haemodialysis, hyperkalaemia is common in patients with end-stage renal disease (ESRD) at interdialytic intervals. Data on hyperkalaemia burden and its effects on dialysis patterns and serum potassium (sK) fluctuations in patients on haemodialysis in China remain limited. The prospective, observational cohort study (PRECEDE-K; NCT04799067) investigated the prevalence, recurrence, and treatment patterns of hyperkalaemia in Chinese patients with ESRD on haemodialysis.

METHODS

Six hundred adult patients were consecutively enrolled from 15 secondary and tertiary hospitals in China. In this interim analysis, we report the baseline characteristics of the cohort, the prevalence of predialysis hyperkalaemia (sK > 5.0 mmol/L), and the trends in serum-dialysate potassium gradient and intradialytic sK shift at Visit 1 (following a long interdialytic interval [LIDI]).

RESULTS

At baseline, most patients (85.6%) received three-times weekly dialysis; mean duration was 4.0 h. Mean urea reduction ratio was 68.0% and Kt/V was 1.45; 60.0% of patients had prior hyperkalaemia (previous 6 months). At Visit 1, mean predialysis sK was 4.83 mmol/L, and 39.6% of patients had hyperkalaemia. Most patients (97.7%) received a dialysate potassium concentration of 2.0 mmol/L. The serum-dialysate potassium gradient was greater than 3 mmol/L for over 40% of the cohort (1- < 2, 2- < 3, 3- < 4, and ≥ 4 mmol/L in 13.6%, 45.1%, 35.7%, and 5.2% of patients, respectively; mean: 2.8 mmol/L). The intradialytic sK reduction was 1- < 3 mmol/L for most patients (0- < 1, 1- < 2, 2- < 3, and ≥ 3 mmol/L in 24.2%, 62.2%, 12.8%, and 0.9% of patients, respectively; mean: 1.4 mmol/L).

CONCLUSIONS

Hyperkalaemia after a LIDI was common in this real-world cohort of Chinese patients despite standard adequate haemodialysis, and led to large serum-dialysate potassium gradients and intradialytic sK shifts. Previous studies have shown hyperkalaemia and sK fluctuations are highly correlated with poor prognosis. Effective potassium-lowering treatments should be evaluated for the improvement of long-term prognosis through the control of hyperkalaemia and sK fluctuations.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT04799067.

Associations of Serum and Dialysate Potassium Concentrations With Incident Atrial Fibrillation in a Cohort Study of Older US Persons Initiating Hemodialysis for Kidney Failure

Introduction

Atrial fibrillation (AF) disproportionally affects persons on maintenance hemodialysis (HD). Associations of serum and dialysate potassium concentrations [K⁺] with AF incidence are poorly understood.

Methods

We conducted a cohort study using Medicare claims merged with clinical data from a dialysis provider to determine whether serum-[K⁺] and/or dialysate-[K⁺] independently associated with AF incidence. Persons insured by fee-for-service Medicare aged ≥67 years at dialysis initiation and free from diagnosed AF prior to day 120 of dialysis were eligible. Serum-[K⁺] and dialysate-[K⁺] were assessed in 30-day intervals and patients were followed-up with for AF incidence in subsequent 30-day intervals.

Results

During 2006 to 2011, 15,190 persons (mean age = 76.3 years) initiating HD had no prior AF diagnosis. Mean serum-[K⁺] was 4.5 mEq/l; dialysate-[K⁺] was 3 mEq/l in 34% and 2 mEq/l in 52% of patients. Followed-up over 21,907 person-years, 2869 persons had incident AF (incidence/100 person-years, 13.1 [95% confidence interval [CI], 12.6-13.6]). The multivariable-adjusted association of serum-[K⁺] with incident AF was J-shaped as follows: relative to a serum-[K⁺] of 4.5 mEq/l, lower serum-[K⁺] associated with increased AF risk, whereas confidence bands for higher serum-[K⁺] indicated no association. Dialysis against a dialysate-[K+] of 3 mEq/l versus 2 mEq/l independently associated with a 14% (95% CI, 5%-24%) lower incidence of AF. No effect modification between serum-[K⁺] and dialysate-[K⁺] was detected (P = 0.34).

Conclusion

Lower serum-[K⁺] was independently associated with incident AF whereas elevated serum-[K+] was not. The findings support adoption of dialysate solutions with a dialysate-[K⁺] of 3 mEq/l, regardless of patients' serum-[K+], and elimination of lower dialysate-[K+] solutions from practice. Clinical trials randomizing patients to different dialysate-[K⁺] are warranted to establish causality.

Lethal ventricular arrhythmia can be prevented by adjusting the dialysate potassium concentration and the use of anti-arrhythmic agents: a case report and literature review

Background

Hypokalemia is common in patients with malnutrition undergoing hemodialysis and is often involved in the development of lethal arrhythmia. Moreover, hemodialysis therapy decreases the serum potassium concentration due to potassium removal to the dialysate. However, it is difficult to adjust the dialysate potassium concentration owing to the use of the central dialysate delivery system in Japan. Here, we have presented a case undergoing hemodialysis with dialysate potassium concentration adjustment to prevent ventricular arrhythmia.

Case presentation

A 56-year-old man with Emery-Dreifuss muscular dystrophy and chronic heart failure was admitted to our hospital and needed subsequent hemodialysis therapy due to renal dysfunction. During hemodialysis, the cardiac resynchronization therapy defibrillator was activated to the treatment of his lethal ventricular arrhythmia. Decreases in serum potassium concentration after hemodialysis and changes in serum potassium concentration during HD were considered the causes of lethal ventricular arrythmia. Therefore, along with using anti-arrhythmic agents, the dialysate potassium concentration was increased from 2.0 to 3.5 mEq/L to minimize changes in the serum potassium concentration during hemodialysis. Post-dialysis hypokalemia disappeared and these changes during hemodialysis were minimized, and no lethal ventricular arrhythmia occurred thereafter.

Conclusions

In this case, we prevented lethal arrhythmia by maintaining the serum potassium concentration by increasing the dialysate potassium concentration, in addition to the use of anti-arrhythmic agents. In the acute phase of patients with frequent lethal arrhythmia undergoing hemodialysis, an increase in dialysate potassium concentration may be an effective method for preventing arrhythmogenic complications.

The effect of hyperkalemia and long inter-dialytic interval on morbidity and mortality in patients receiving hemodialysis: a systematic review

BACKGROUND

Patients with chronic kidney disease, especially those receiving hemodialysis (HD), are at risk of hyperkalemia (HK). This systematic review aimed to evaluate the prevalence of HK in patients with renal disease receiving HD and collate evidence on the effect of HK and differing HD patterns (i.e., long vs. short inter-dialytic intervals [LIDI and SIDI, respectively] in a thrice weekly schedule) on mortality.

METHODS

Comprehensive searches were conducted across six databases and selected conference proceedings by two independent reviewers up to September 2020. A hundred and two studies reporting frequency of HK, mortality, or cardiovascular (CV) outcomes in adult patients with acute, chronic or end-stage renal disease in receipt of HD were included. Narrative synthesis of results was undertaken with key findings presented in tables and figures.

RESULTS

Median prevalence of HK in patients with renal disease receiving HD was 21.6% and increased in patients receiving concomitant medications - mainly renin-angiotensin-aldosterone system inhibitors and potassium-sparing diuretics. Associations between elevated potassium levels and increased risk of both all-cause and CV mortality in the HD population were consistent across the included studies. In addition, there was a rise in all-cause and CV mortality on the day following LIDI compared with the day after the two SIDIs in patients on HD.

CONCLUSIONS

Evidence identified in this systematic review indicates a relationship between HK and LIDI with mortality in patients with renal disease receiving HD, emphasizing the need for effective monitoring and management to control potassium levels both in emergency and chronic HD settings.

Association between serum potassium and risk of all-cause mortality among chronic kidney diseases patients: A systematic review and dose-response meta-analysis of more than one million participants

We aimed to perform a meta-analysis, using prospective cohort studies, to test the association between serum potassium and all-cause mortality among chronic kidney diseases (CKD) patients. A systematic search was performed using PubMed-MEDLINE and Scopus, up to July 2020. Prospective cohort studies which reported risk estimates of all-cause mortality in CKD patients with different serum potassium levels were included in the present meta-analysis. Thirteen studies were included in the analysis. A nonlinear dose-response meta-analysis suggested that there is a J-shaped association between serum potassium levels and the risk of all-cause mortality, with a nadir at serum potassium of 4.5 mmol/L. Subgroup analyses indicated that the strength and shape of the association between serum potassium and all-cause mortality may be influenced by age. Our meta-analysis provides supportive evidence that there is a J-shape association between serum potassium and all-cause mortality among CKD patients.

The cardiovascular-dialysis nexus: the transition to dialysis is a treacherous time for the heart

Chronic kidney disease (CKD) patients require dialysis to manage the progressive complications of uraemia. Yet, many physicians and patients do not recognize that dialysis initiation, although often necessary, subjects patients to substantial risk for cardiovascular (CV) death. While most recognize CV mortality risk approximately doubles with CKD the new data presented here show that this risk spikes to >20 times higher than the US population average at the initiation of chronic renal replacement therapy, and this elevated CV risk continues through the first 4 months of dialysis. Moreover, this peak reflects how dialysis itself changes the pathophysiology of CV disease and transforms its presentation, progression, and prognosis. This article reviews how dialysis initiation modifies the interpretation of circulating biomarkers, alters the accuracy of CV imaging, and worsens prognosis. We advocate a multidisciplinary approach and outline the issues practitioners should consider to optimize CV care for this unique and vulnerable population during a perilous passage.

Prescription patterns of dialysate potassium and potassium binders and survival on haemodialysis-the French Renal Epidemiology and Information Network registry

BACKGROUND

Management of potassium disorders in patients on haemodialysis (HD) is complex. We studied prescription patterns of dialysate potassium and potassium binders, and their associations with patient survival.

METHODS

This national registry-based study included 25 629 incident adult patients alive after 3 months of HD from 2010 through 2013 and followed-up through 31 December 2014. We used Cox proportional hazard models to estimate multiadjusted mortality hazard ratios (HRs) associated with time-dependent exposure to facility-level dialysate potassium concentrations and patient-level potassium binder exposure.

RESULTS

Almost all dialysis units used, and generally most often, dialysate potassium concentrations of 2 mmol/L. During this period, use of concentrations <2 mmol/L tended to decrease and those ≥3 mmol/L to increase. In 2014, 9% of units used a single dialysate formula, 41% used two and 50% three or more. The most frequent combinations were 2 and 3 mmol/L (40%), and <2, 2 and 3 mmol/L (37%). Compared with patients on HD in units using only one dialysate formula, those in units using two or three had adjusted mortality HRs of 0.91 [95% confidence interval (CI) 0.82-1.01] and 0.84 (0.75-0.93), respectively. Potassium binders were prescribed for 37% of all patients at baseline. Adjusted mortality HRs associated with doses <4, 4-8 and ≥8 g/day versus none were 1.22 (95% CI 1.04-1.51), 0.6 (0.54-0.66) and 0.25 (0.24-0.33), respectively.

CONCLUSIONS

Diversity in facility-level use of dialysate potassium concentrations and potassium binder use at an appropriate dose appear to be associated with better survival in HD patients.

Hemodialysis treatment in patients with severe electrolyte disorders: Management of hyperkalemia and hyponatremia

Significant deviations of serum potassium and sodium levels are frequently observed in hospitalized patients and are both associated with increased all‐cause and cardiovascular mortality. The presence of acute or chronic renal failure facilitates the pathogenesis and complicates the clinical management. In the absence of reliable outcome data in the context of dialysis prescription, requirement of renal replacement therapy in patients with severe electrolyte disturbances constitutes a therapeutic challenge. Recommendations for intradialytic management are based on pathophysiologic reasoning and clinical observations only, and as such, heterogeneous and limited to expert opinion level. This article reviews current strategies for the management of severe hyperkalemia and hyponatremia in hemodialysis patients.

Fluctuations in plasma potassium in patients on dialysis

Plasma potassium concentration is maintained in a narrow range to avoid deleterious electrophysiologic consequences of both abnormally low and high levels. This is achieved by redundant physiologic mechanisms, with the kidneys playing a central role in maintaining both short-term plasma potassium stability and long-term total body potassium balance. In patients with end-stage renal disease, the lack of kidney function reduces the body’s ability to maintain normal physiologic potassium balance. Routine thrice-weekly dialysis therapy achieves long-term total body potassium mass balance, but the intermittent nature of dialytic therapy can result in wide fluctuations in plasma potassium concentration and consequently contribute to an increased risk of arrhythmogenicity. Various dialytic and nondialytic interventions can reduce the magnitude of these fluctuations, but the impact of such interventions on clinical outcomes remains unclear.

A simple modification of dialysate potassium: its impact on plasma potassium concentrations and the electrocardiogram

Background

Sudden death is frequent in haemodialysis (HD) patients. Both hyperkalaemia and change of plasma potassium (K) concentrations induced by HD could explain this. The impact of increasing dialysate K by 1 mEq/L on plasma K concentrations and electrocardiogram (ECG) results before and after HD sessions was studied.

Methods

Patients with pre-dialysis K >5.5 mEq/L were excluded. ECG and K measurements were obtained before and after the first session of the week for 2 weeks. Then, K in the dialysate was increased (from 1 or 3 to 2 or 4 mEq/L, respectively). Blood and ECG measurements were repeated after 2 weeks of this change.

Results

Twenty-seven prevalent HD patients were included. As expected, a significant decrease in K concentrations was observed after the dialysis session, but this decrease was significantly lower after the switch to an increased dialysate K. The pre-dialysis K concentrations were not different after changing, but post-dialysis K concentrations were higher after switching (P < 0.0001), with a lower incidence of post-dialysis hypokalaemia. Regarding ECG, before switching, the QT interval (QT) dispersion increased during the session, whereas no difference was observed after switching. One week after switching, post-dialysis QT dispersion [38 (34-42) ms] was lower than post-dialysis QT dispersion 2 weeks and 1 week before switching [42 (38-57) ms, P = 0.0004; and 40 (35-50) ms, P = 0.0002].

Conclusions

A simple increase of 1 mEq/L of K in the dialysate is associated with a lower risk of hypokalaemia and a lower QT dispersion after the dialysis session. Further study is needed to determine if such a strategy is associated with a lower risk of sudden death.

Renal Association Clinical Practice Guideline on Haemodialysis

This guideline is written primarily for doctors and nurses working in dialysis units and related areas of medicine in the UK, and is an update of a previous version written in 2009. It aims to provide guidance on how to look after patients and how to run dialysis units, and provides standards which units should in general aim to achieve. We would not advise patients to interpret the guideline as a rulebook, but perhaps to answer the question: "what does good quality haemodialysis look like?"The guideline is split into sections: each begins with a few statements which are graded by strength (1 is a firm recommendation, 2 is more like a sensible suggestion), and the type of research available to back up the statement, ranging from A (good quality trials so we are pretty sure this is right) to D (more like the opinion of experts than known for sure). After the statements there is a short summary explaining why we think this, often including a discussion of some of the most helpful research. There is then a list of the most important medical articles so that you can read further if you want to - most of this is freely available online, at least in summary form.A few notes on the individual sections: 1. This section is about how much dialysis a patient should have. The effectiveness of dialysis varies between patients because of differences in body size and age etc., so different people need different amounts, and this section gives guidance on what defines "enough" dialysis and how to make sure each person is getting that. Quite a bit of this section is very technical, for example, the term "eKt/V" is often used: this is a calculation based on blood tests before and after dialysis, which measures the effectiveness of a single dialysis session in a particular patient. 2. This section deals with "non-standard" dialysis, which basically means anything other than 3 times per week. For example, a few people need 4 or more sessions per week to keep healthy, and some people are fine with only 2 sessions per week - this is usually people who are older, or those who have only just started dialysis. Special considerations for children and pregnant patients are also covered here. 3. This section deals with membranes (the type of "filter" used in the dialysis machine) and "HDF" (haemodiafiltration) which is a more complex kind of dialysis which some doctors think is better. Studies are still being done, but at the moment we think it's as good as but not better than regular dialysis. 4. This section deals with fluid removal during dialysis sessions: how to remove enough fluid without causing cramps and low blood pressure. Amongst other recommendations we advise close collaboration with patients over this. 5. This section deals with dialysate, which is the fluid used to "pull" toxins out of the blood (it is sometimes called the "bath"). The level of things like potassium in the dialysate is important, otherwise too much or too little may be removed. There is a section on dialysate buffer (bicarbonate) and also a section on phosphate, which occasionally needs to be added into the dialysate. 6. This section is about anticoagulation (blood thinning) which is needed to stop the circuit from clotting, but sometimes causes side effects. 7. This section is about certain safety aspects of dialysis, not seeking to replace well-established local protocols, but focussing on just a few where we thought some national-level guidance would be useful. 8. This section draws together a few aspects of dialysis which don't easily fit elsewhere, and which impact on how dialysis feels to patients, rather than the medical outcome, though of course these are linked. This is where home haemodialysis and exercise are covered. There is an appendix at the end which covers a few aspects in more detail, especially the mathematical ideas. Several aspects of dialysis are not included in this guideline since they are covered elsewhere, often because they are aspects which affect non-dialysis patients too. This includes: anaemia, calcium and bone health, high blood pressure, nutrition, infection control, vascular access, transplant planning, and when dialysis should be started.

Association of Abnormal Serum Potassium Levels with Arrhythmias and Cardiovascular Mortality: a Systematic Review and Meta-Analysis of Observational Studies

PURPOSE

To provide the first systematic review and meta-analysis of observational studies on the association of abnormal serum potassium and cardiovascular outcomes.

METHODS

Medline and ISI Web of Knowledge were systematically searched from inception until November 24, 2017. Data synthesis of relevant studies was performed using random effects model meta-analyses.

RESULTS

Meta-analyses included 310,825 participants from 24 studies. In the older general population, low serum potassium was associated with a 1.6-fold increased risk of supraventricular arrhythmias (risk ratio [95% confidence interval] 1.62 [1.02-2.55]). Contrarily, high serum potassium was associated with increased cardiovascular mortality (CVM) (1.38 [1.14-1.66]). In patients with acute myocardial infarction, the risk of ventricular arrhythmias was increased for high serum potassium (2.33 [1.60-3.38]). A U-shaped association was observed with a composite cardiovascular outcome in hypertensive patients (2.6-fold increased risk with hypokalemia and 1.7-fold increased risk with hyperkalemia), with CVM in dialysis patients (1.1-fold increased risk with hypokalemia and 1.4-fold increased risk with hyperkalemia) and with CVM in heart failure patients (albeit not statistically significant). Further, only hyperkalemia was associated with an increased risk of a composite cardiovascular outcome in both dialysis (1.12 [1.03-1.23]) and chronic kidney disease (1.34 [1.06-1.71]) patients.

CONCLUSIONS

Controlled clinical trials are needed to determine which populations may profit from more frequent potassium-monitoring and subsequent interventions, e.g., change or withdrawal of potassium-influencing drugs, in order to restore normal values and prevent cardiovascular outcomes.

REGISTRATION DETAILS

Registration in PROSPERO (Centre for Reviews and Dissemination University of York, York, UK): CRD42016048897 ( https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=48897 ).

Errors of Classification With Potassium Blood Testing: The Variability and Repeatability of Critical Clinical Tests

OBJECTIVE

To understand the performance of a currently used clinical blood test with regard to the frequency and size of variation of the results.

PATIENTS AND METHODS

From November 29, 2012, through November 29, 2013, patients were recruited at 65 sites as part of a previously reported clinical trial (ClinicalTrials.gov Identifier: NCT01737697). Eligible outpatients who had been fasting for at least 8 hours underwent venous phlebotomy at baseline, 30 minutes, and 60 minutes to measure plasma potassium levels in whole blood using a point-of-care device (i-STAT, Abbott Laboratories). We analyzed the results to assess their variability and frequency of pseudohyperkalemia and pseudonormokalemia.

RESULTS

A total of 1170 patients were included in this study. Absolute differences between pairs of measurements from different time points ranged from 0 to 2.5 mmol/L, with a mean difference of 0.26 mmol/L. The mean percentage differences were approximately 5% with an SD of 5%. Approximately 12% of differences between repeated fasting potassium blood test results were above 0.5 mmol/L (33% of the normal range), and 20% of patients (234) had at least one difference greater than 0.5 mmol/L. In 44.0% of the patients with a hyperkalemic average value (true hyperkalemia) (302 of 686), at least one blood test result was in the normal range (pseudonormokalemia), and in 30.2% of the patients with a normal average value (146 of 484), at least one blood test result was elevated (pseudohyperkalemia).

CONCLUSION

Expected variability and errors exist with potassium blood tests, even when conditions are optimized. Pseudohyperkalemia and pseudonormokalemia are common, indicating a need for thoughtful clinical interpretation of unexpected test results.

Dialysate Potassium, Dialysate Magnesium, and Hemodialysis Risk

One of the fundamental goals of the hemodialysis prescription is to maintain serum potassium levels within a narrow normal range during both the intradialytic and interdialytic intervals. Considering the extraordinarily high rate of cardiovascular mortality in the hemodialysis population, clinicians are obligated to explore whether factors related to dialytic potassium removal can be modified to improve clinical outcomes. Observational studies and circumstantial evidence suggest that extreme concentrations of serum and dialysate potassium can trigger cardiac arrest. In this review, we provide an overview of factors affecting overall potassium balance and factors modulating potassium dialysate fluxes in dialysis, and we review data linking serum and dialysate potassium concentrations with arrhythmias, cardiovascular events, and mortality. We explore potential interactions between serum and dialysate magnesium levels and risks associated with dialysate potassium levels. Finally, we conclude with proposed dialytic and novel nondialytic approaches to optimize outcomes related to potassium homeostasis in patients on hemodialysis. Dialysis clinicians need to consider changes in the overall clinical scenario when choosing dialysate potassium concentrations, and an effective change in practice will require more frequent serum potassium monitoring and responsive dialysis care teams.

Treatment of Severe Hyperkalemia: Confronting 4 Fallacies

Severe hyperkalemia is a medical emergency that can cause lethal arrhythmias. Successful management requires monitoring of the electrocardiogram and serum potassium concentrations, the prompt institution of therapies that work both synergistically and sequentially, and timely repeat dosing as necessary. It is of concern then that, based on questions about effectiveness and safety, many physicians no longer use 3 key modalities in the treatment of severe hyperkalemia: sodium bicarbonate, sodium polystyrene sulfonate (Kayexalate [Concordia Pharmaceuticals Inc., Oakville, ON, Canada], SPS [CMP Pharma, Farmville, NC]), and hemodialysis with low potassium dialysate. After reviewing older reports and newer information, I believe that these exclusions are ill advised. In this article, I briefly discuss the treatment of severe hyperkalemia and detail why these modalities are safe and effective and merit inclusion in the treatment of severe hyperkalemia.

We Use Dialysate Potassium Levels That Are Too Low in Hemodialysis

Sudden cardiac death accounts for a quarter of all deaths in hemodialysis patients. While this group is at high risk for cardiovascular events, there are certain modifiable factors that have been associated with higher risk of sudden cardiac death. These include short dialysis time, high ultrafiltration rate, and dialysate with a low potassium or calcium concentration. While it is impossible to discern the relative contribution of each of these factors, our review focuses on the role of dialysate potassium concentration in sudden cardiac death. Retrospective studies have identified low potassium dialysate (<2-3 mEq/l) as a risk factor for sudden cardiac death, particularly in patients with predialysis serum potassium concentrations <5 mEq/l. However, patients with predialysis hyperkalemia (≥5.5 mEq/l) may be an exception since a significant association of low potassium dialysate with sudden cardiac death was not observed in this subgroup. Dialysis prescribers must employ alternatives to low dialysate potassium concentrations to achieve potassium control such as increasing dialysis time and frequency, dietary restriction of potassium, prevention and treatment of constipation, discontinuation of medications contributing to hyperkalemia and traditional (or newer, better tolerated) potassium binding resins. Finally, one must also address other factors associated with sudden cardiac death such as short dialysis time, high ultrafiltration rate, and low calcium concentration dialysate.