An Evidence-Based Narrative Review of the Emergency Department Management of Acute Hyperkalemia

The influence of undetected hemolysis on POCT potassium results in the emergency department

OBJECTIVES

This study aimed to evaluate discrepancies in potassium measurements between point-of-care testing (POCT) and central laboratory (CL) methods, focusing on the impact of hemolysis on these measurements and its impact in the clinical practice in the emergency department (ED).

METHODS

A retrospective analysis was conducted using data from three European university hospitals: Technische Universitat Munchen (Germany), Hospital Universitario La Paz (Spain), and Erasmus University Medical Center (The Netherlands). The study compared POCT potassium measurements in EDs with CL measurements. Data normalization was performed in categories for potassium levels (kalemia) and hemolysis. The severity of discrepancies between POCT and CL potassium measurements was assessed using the reference change value (RCV).

RESULTS

The study identified significant discrepancies in potassium between POCT and CL methods. In comparing POCT normo- and mild hypokalemia against CL results, differences of -4.20 % and +4.88 % were noted respectively. The largest variance in the CL was a +4.14 % difference in the mild hyperkalemia category. Additionally, the RCV was calculated to quantify the severity of discrepancies between paired potassium measurements from POCT and CL methods. The overall hemolysis characteristics, as defined by the hemolysis gradient, showed considerable variation between the testing sites, significantly affecting the reliability of potassium measurements in POCT.

CONCLUSIONS

The study highlighted the challenges in achieving consistent potassium measurement results between POCT and CL methods, particularly in the presence of hemolysis. It emphasised the need for integrated hemolysis detection systems in future blood gas analysis devices to minimise discrepancies and ensure accurate POCT results.

Management of hyperkalemia in children

PURPOSE OF REVIEW

Hyperkalemia is a potentially fatal electrolyte abnormality with no standardized management. The purpose of this review is to provide the knowledge needed for timely and effective management of hyperkalemia in children. It describes the utility of existing and novel therapies.

RECENT FINDINGS

Two newer oral potassium binding agents, patiromer sorbitex calcium and sodium zirconium cyclosilicate, have been FDA-approved for the management of hyperkalemia in adults. These newer agents offer hope for improved management, even though their use in pediatric patients requires further exploration.

SUMMARY

This review highlights the causes and life-threatening effects of hyperkalemia and provides a comprehensive overview of the management of hyperkalemia in both acute and chronic settings along with upcoming treatment strategies.

Implications of differences between point-of-care blood gas analyser and laboratory analyser potassium results on hyperkalaemia diagnosis & treatment

BACKGROUND

Hyperkalaemia is managed in the emergency department (ED) following measurement of potassium results by blood gas analysers (BGA) or laboratory analysers (LAB).

AIMS

To determine the prevalence of clinically significant differences between BGA and LAB potassium results and the impact on ED hyperkalaemia management.

METHODS

Retrospective analysis of time-matched ED BGA and LAB potassium samples from 2019 to 2020 (taken within 15 min, one or both results ≥6.0 mmol/L). Mean differences and 95% limits of agreement (LoA) were determined for pairs with one or both results ≥6.0 mmol/L and a separate 500 consecutive sample pairs.

RESULTS

Four hundred eighty-eight matched BGA and LAB samples met the inclusion criteria. Of these, 201 (41.2%) differed by ≤0.5 mmol/L, 169 (34.6%) included a haemolysed LAB sample, and 12 (2.5%) had an unreportable BGA sample. One hundred six (21.7%) pairs differed by >0.5 mmol/L, and 60/106 (57%) had normal LAB potassium results, but BGA indicated moderate/severe hyperkalaemia (two of these pairs received hyperkalaemia treatment). Of patients with a haemolysed LAB sample, or where pairs differed by >0.5 mmol, 48 were treated with insulin and five (10.4%) experienced hypoglycaemia. Mean differences and LoA for pairs with LAB results <6.0 mmol/L but BGA ≥6.0 mmol/L demonstrated unacceptable agreement, with 18 (25.7%) BGA results exceeding 8.0 mmol/L.

CONCLUSIONS

Potentially significant discordance may occur between BGA and LAB potassium results. Clinicians need to be aware of factors impacting both analytical methods' accuracy (such as poor venepuncture or sample handling, (K) EDTA interference) and undetectable haemolysis with BGA measurements. We recommend BGA hyperkalaemia be confirmed with LAB results using a non-haemolysed sample where time permits.

Managing Hyperkalemia in the Modern Era: A Case-Based Approach

The last decade has seen tremendous advances in the prevention and treatment of recurrent hyperkalemia. In this narrative review, we aim to highlight contemporary data on key areas in the epidemiology and management of hyperkalemia. Focusing on drug-induced hyperkalemia (the implications of renin-angiotensin-aldosterone system inhibitors [RAASi] discontinuation and the role of mineralocorticoid receptor antagonists), newer concurrent therapies that modify potassium handling (sodium-glucose transporter 2 inhibitors [SGLT2i]), the introduction of new treatment agents (oral potassium binding agents), and the controversial role of dietary potassium restriction, we apply recent research findings and review the evidence in a case-based format.

Patiromer utility as an adjunct treatment in patients needing urgent hyperkalaemia management (PLATINUM): design of a multicentre, randomised, double-blind, placebo-controlled, parallel-group study

INTRODUCTION

Hyperkalaemia is common, life-threatening and often requires emergency department (ED) management; however, no standardised ED treatment protocol exists. Common treatments transiently reducing serum potassium (K+) (including albuterol, glucose and insulin) may cause hypoglycaemia. We outline the design and rationale of the Patiromer Utility as an Adjunct Treatment in Patients Needing Urgent Hyperkalaemia Management (PLATINUM) study, which will be the largest ED randomised controlled hyperkalaemia trial ever performed, enabling assessment of a standardised approach to hyperkalaemia management, as well as establishing a new evaluation parameter (net clinical benefit) for acute hyperkalaemia treatment investigations.

METHODS AND ANALYSIS

PLATINUM is a Phase 4, multicentre, randomised, double-blind, placebo-controlled study in participants who present to the ED at approximately 30 US sites. Approximately 300 adult participants with hyperkalaemia (K+ ≥5.8 mEq/L) will be enrolled. Participants will be randomised 1:1 to receive glucose (25 g intravenously <15 min before insulin), insulin (5 units intravenous bolus) and aerosolised albuterol (10 mg over 30 min), followed by a single oral dose of either 25.2 g patiromer or placebo, with a second dose of patiromer (8.4 g) or placebo after 24 hours. The primary endpoint is net clinical benefit, defined as the mean change in the number of additional interventions less the mean change in serum K+, at hour 6. Secondary endpoints are net clinical benefit at hour 4, proportion of participants without additional K+-related medical interventions, number of additional K+-related interventions and proportion of participants with sustained K+ reduction (K+ ≤5.5 mEq/L). Safety endpoints are the incidence of adverse events, and severity of changes in serum K+ and magnesium.

ETHICS AND DISSEMINATION

A central Institutional Review Board (IRB) and Ethics Committee provided protocol approval (#20201569), with subsequent approval by local IRBs at each site, and participants will provide written consent. Primary results will be published in peer-reviewed manuscripts promptly following study completion.

TRIAL REGISTRATION NUMBER

NCT04443608.

Electrocardiography is Unreliable to Detect Potential Lethal Hyperkalemia in Patients with Non-dialysis Chronic Kidney Disease

Hemodialysis patients with hypercalcemia are less likely to manifest the usual electrocardiographic changes associated with hyperkalemia than in those with normal renal function. This study was conducted to determine whether electrocardiography (ECG) is a reliable indicator to detect severe life-threatening hyperkalemia in non-dialysis CKD patients. The study was conducted at three referral university hospitals between July 2017 and June 2018. Severe hyperkalemia was defined as serum potassium concentration ≥ 8.0 mEq/L. Serum potassium, sodium, bicarbonate, calcium, and creatinine concentrations were measured and simultaneous 12-lead ECG was obtained. Patients with end-stage renal disease receiving renal replacement therapy were excluded. Also excluded were patients with the usual ECG abnormalities to hyperkalemia. Of the 438 patients screened, 10 (2.3%) aged 2-14 years with severe hyperkalemia and normal ECG findings were identified. Median serum potassium level was 8.6 mEq/L (range 8.2-9.0). All had regular sinus rhythm. P, QRS, ST segment, T morphology, PR and QT interval, and QRS duration were all normal. Hyperkalemia was associated with CKD, metabolic acidosis, and hypercalcemia in all cases. Therapy with intravenous 0.9% saline, sodium bicarbonate, glucose, insulin, calcium, and salbutamol corrected the hyperkalemia in 7 patients. The remaining three patients evinced arrhythmias requiring hemodialysis. Although rare, non-dialysis CKD patients with hypercalcemia may not manifest the usual electrographic abnormalities associated with hyperkalemia. Thus, a normal ECG finding in non-dialysis CKD patients should be interpreted with caution.

Hyperkalaemia in the emergency department: Epidemiology, management and monitoring of treatment outcomes

OBJECTIVE

To describe the epidemiology, treatment and monitoring of treatment outcomes of patients presenting to the ED with hyperkalaemia.

METHODS

We undertook a retrospective observational study in a mixed adult/paediatric ED over five 3-month periods. Consecutive patients were included if they had an initial serum or blood gas potassium ≥6.0 mmol/L. Patients were excluded if their principal diagnosis was diabetic ketoacidosis, their blood sample was haemolysed or the blood gas result was inconsistent with a subsequent serum potassium. Data were extracted from electronic medical records and two senior emergency registrars independently assessed available ECGs. Moderate and severe hyperkalaemia were potassium 6.0-6.4 and ≥6.5 mmol/L, respectively.

RESULTS

Overall, 392 patients were included (mean age 73.7 years, triage category 1 or 2 28.3%, admitted 91.3%). Three hundred and twenty-one (81.9%, 95% confidence interval [CI] 77.6-85.5%) patients took one or more medications that predispose to hyperkalaemia and 335 (85.5%, 95% CI 81.5-88.7%) had one or more predisposing comorbidities. Two hundred and seventy-one (69.1%, 95% CI 64.3-73.6%) patients had moderately severe and 121 (30.9%, 95% CI 26.4-35.7%) had severe hyperkalaemia. Two hundred and fifty-nine (66.1%, 95% CI 61.1-70.7%) patients were administered at least one medication in ED to lower the potassium concentration and 51 (13.0%, 95% CI 9.9-16.8%) were dialysed. One hundred and eighty-seven patients received intravenous insulin: 40 (21.4%) had documented biochemical hypoglycaemia, but 45 (24.1%) had no post-insulin blood glucose level documented. Hyperkalaemia-associated ECG changes were uncommon.

CONCLUSION

Most ED patients with hyperkalaemia have identifiable clinical and medication-related risk factors. Variations in care were widespread and monitoring for iatrogenic adverse events was suboptimal.

3rd-Degree Atrioventricular Block

Audience

This oral boards case is appropriate for emergency medicine residents and medical students on emergency medicine rotations.

Introduction/Background

Third-degree heart block (also known as complete heart block) is a cardiovascular emergency that requires prompt recognition. Complete heart block is a type of atrioventricular (AV) block whereby no atrial impulses reach the ventricular conduction system. The most common etiology of AV block is ischemic heart disease, with up to 1 in 5 patients developing some type of conduction disturbance after an MI.1 Complete heart block is seen in 8% of patients post-MI.2 Other causes include myocarditis, infectious endocarditis, infiltrative cardiac disease, congenital AV blocks, non-ischemic cardiomyopathy, electrolyte disturbances, and drug side effects.3 In complete heart block, the heart rate is dependent on the location of the block and a functioning secondary pacemaker within the conduction system. Analysis of the EKG will determine the location of this escape rhythm. For escape rhythms originating at the AV node or high in the His-Purkinje system, the QRS complex will typically be narrow, and the ventricular rate typically in the 40-60 bpm range. For blocks with ventricular escape rhythms, the QRS will appear wide, with rates of 20-40 bpm. Patients presenting with 3rd-degree AVB with ventricular escape rhythms can destabilize. If no escape rhythm generates, patients develop asystole and cardiac arrest. Since 1 in 600 adults over the age of 65 will develop a form of supraventricular conduction abnormality each year, this disease process is important to identify and treat.4 Effective management includes accurate interpretation of a 12-lead EKG, assessment of hemodynamic stability and systemic perfusion, and time-sensitive pharmacologic or procedural intervention.

Educational Objectives

At the end of this oral board session, examinees will: 1) demonstrate ability to obtain a complete medical history including detailed cardiac history, 2) demonstrate the ability to perform a detailed physical examination in a patient with cardiac complaints, 3) investigate the broad differential diagnoses which include acute coronary syndrome (ACS), electrolyte imbalances, pulmonary embolism, cerebrovascular accident, aortic dissection and arrhythmias, 4) obtain and interpret the cardiac monitor rhythm strip to identify complete heart block, 5) list the appropriate laboratory and imaging studies to differentiate arrhythmia from other diagnoses (complete blood count, comprehensive metabolic panel, magnesium level, EKG, troponin level, chest radiograph), 6) identify a patient with complete heart block and manage appropriately (administer IV atropine, attempt transcutaneous pacing, place a transvenous pacemaker, emergent consultation with interventional cardiology), 7) provide appropriate disposition to intensive care after consultation with interventional cardiologist.

Educational Methods

This is a straight-forward case which was written to assess learners' ability to rapidly recognize an unstable cardiac rhythm and to subsequently treat and stabilize the patient. Oral board testing is used as a proxy for the emergency department (ED) and can assist with periodic assessment of resident performance while in the ED.We have found that oral board testing is a useful tool to assess residents' critical thinking while still applying pressure that is needed to pass the examination itself. Large groups of residents can be assessed in a short time period without needing to "wait" for a particular clinical condition to present to the ED.In this case, learners were assessed using a free online evaluation tool, ie, Google forms. Multiple questions were written for each critical action, and the Google form served as the online evaluation and repository. The critical actions of the case were then tied to Emergency Medicine Milestones, and the results were compiled for use during residency clinical competency evaluations. Residents were provided with immediate verbal feedback of their performance and were also given their electronic evaluations when requested.

Research Methods

Learners and instructors were given the opportunity to provide electronic feedback after the case was completed to assess strengths and weaknesses, and subsequent modifications were made. Additionally, learners answered written multiple-choice questions after the case to assess for retention of the material.

Results

Senior learners found this to be a more enjoyable way to refresh their skills than direct lecture. Junior residents and students who encountered this clinical entity first in the oral board rather than in the ED, stated that they enjoyed the ability to "trial run" the case before being faced with an emergent and uncontrolled setting of the ED. Overall, the learners rated the case as 4.7 (1-5 Likert scale, 5 being excellent) after the mock oral board examination was completed.

Discussion

Students and residents who were assessed with a mock oral board session found this to be an improvement over traditional "lecture" and were pleased to have participated. The content is highly relevant to emergency medicine and the format forces learners to be actively engaged in review of the material. The case is a good model for the high stakes testing of written and oral board examinations, and is an effective way to assess a resident's ability to rapidly assess and manage a life-threatening condition in the ED.

Topics

Third-degree AV block, complete heart block, 3^rd-degree block, hypotension, syncope, bradycardia, cardiovascular emergency.