Expert panel consensus on hyperkalemia in emergency department
USA: A recent study in the Journal of the American College of Emergency Physicians Open (JACEP Open) has reported an expert panel consensus on hyperkalemia (HK) management in the emergency department.
The panel led by Zubaid Rafique from Ben Taub General Hospital, Houston, Texas, USA, was composed of 7 medical practitioners, including 5 physicians, a nurse, and a clinical pharmacist with collective expertise in the areas of emergency medicine, nephrology, and hospital medicine. This panel was sponsored by the American College of Emergency Physicians with a goal to create a consensus document for managing acute hyperkalemia. The panel evaluated the evidence on calcium for myocyte stabilization and potassium shifting and excretion.
Hyperkalemia is a common electrolyte abnormality identified in the emergency department (ED) and potentially fatal. However, there is no consensus over the potassium threshold that warrants intervention or its treatment algorithm.
The study summarizes information on available therapies for hyperkalemia and proposes a hyperkalemia treatment algorithm for the ED practitioner based on the currently available literature and highlights diagnostic pitfalls and evidence gaps.
Clinical Presentation and Diagnosis
Because HK manifests in non-specific symptoms, it is prudent to consider the entire clinical picture when diagnosing or treating patients.
The total body potassium is approximately 3000 mEq, 98% of which is stored intracellularly. In normal physiologic conditions, the intracellular potassium concentration is approximately 140 mEq/L whereas the extracellular concentration ranges between 3.5 and 5 mEq/L. This balance of plasma potassium is maintained by active Na-K-ATPase pumps and passive potassium efflux, thus setting the resting membrane potential needed for normal nerve, cardiac, and muscle function.
HK decreases the transmembrane potassium gradient leading to increased potassium conductance and shortening the duration of the action potential. This results in ST-segment depression, peaked T waves, and Q-T interval shortening. As potassium levels rise, prolongation of the PR and QRS duration occurs that leads to a sinewave complex and ultimately to ventricular fibrillation or asystole. Hence it is recommended to obtain an ECG early in the evaluation of patients with HK.
Not all measures of HK represent the actual potassium concentration. Because aggressive treatment of pseudo-HK is unnecessary and potentially lethal, clinicians must distinguish true HK from pseudo-HK and spurious HK.
Acute management recommendations involve a threefold approach: (1) stabilization of the cardiac membranes, (2) redistribution of potassium, and (3) elimination of potassium. Multiple potassium lowering agents are available, and they can be used individually or in combination based on severity of HK or institutional protocol.
The effect of potassium on myocytes is counterbalanced by the concurrent calcium concentration. It improves or totally reverses HK-related ECG changes, arrhythmias, or cardiac arrest. The initial dose may be repeated if there is no effect within 5–10 minutes.
Dextrose (glucose) is administered with insulin to prevent hypoglycemia and subsequent doses may be warranted if hypoglycemia persists.
Albuterol may be ineffective in some patients, and the mechanism of resistance is not understood. Common side effects are tremor, palpitations, headache, and mild hyperglycemia, which may alleviate insulin-induced hypoglycemia when used simultaneously.
Currently, there is insufficient evidence to support the use of intravenous sodium bicarbonate for the acute treatment of HK, and it should be used with caution because it can cause sodium and fluid overload.
Although loop diuretics are effective at promoting potassium excretion, evidence for use of loop diuretics in the acute management of HK is lacking. These agents may be considered for use as adjuncts in a hyperkalemic emergency.
In life-threatening HK, hemodialysis is the best option to reduce potassium effectively, and thus vascular access needs to be established emergently in patients who do not already have one.
Though routinely used in the management of HK in the emergency setting, oral potassium binders have yet to be approved for the emergency treatment of life-threatening HK. The newer binders appear to be safe and current investigations are underway to determine their effectiveness on lowering potassium in the acute setting and the subsequent impact on patient outcomes. Currently available binders are sodium polystyrene sulfonate, patiromer, and sodium zirconium cyclosilicate.
Management Algorithm and Disposition
Patients with K > 5.5 mEq/L and presenting to the ED with acute illness are eligible to enter the algorithm.
Step 1: Because pseudo-HK and spurious HK lead to falsely elevated potassium levels, and many EDs use point-of-care blood testing, which cannot detect hemolysis, it is important to verify the potassium level before starting treatment. Hence, the first step in this algorithm is to assess pretest probability of HK by reviewing medical history (DM, congestive HF, CKD), current medications and laboratory abnormalities; note that an isolated K elevation may signify a spurious result. If the history does not fit with laboratory findings, consider retesting from a fresh blood draw.
Step 2: The next step is to evaluate cardiac involvement. If new changes are found, administer calcium gluconate intravenous 1 g as per the algorithm, and repeat as needed. Calcium gluconate is preferred because calcium chloride carries the risk of tissue necrosis in case of extravasation. However, in the hemodynamically unstable patient, calcium chloride may be preferred because it carries 3 times the amount of elemental calcium than that of the gluconate formulation.
Step 3: Treatment options are based on K levels and categorized into redistribution and elimin
Step 4: Reassessment of HK is indicated every 2 to 4 hours because most temporizing agents manifest their maximal effect within 2 hours and are likely wearing off by 4 hours. At this point if K > 6 mEq/L, consider redosing with medications (Step 2) and arranging hemodialysis. If K < 6 mEq/L, consider proceeding to the disposition step.
Disposition: Patients should be frequently assessed for abnormal vital signs, rebound HK, and side effects of medications administered. Hemodynamic instability, persistent new ECG abnormality, and new onset HK should be admitted for further evaluation. Admission should also be considered if HK is recalcitrant to acute treatment or in whom potassium was not eliminated (ie, excreted or dialyzed) but only redistributed. Yet for others, discharge should be considered when all of the following apply: (1) the patient has chronic HK, and a cause for the current exacerbation has been identified and rectified; (2) the patient has stable vital signs and feels well to go home; (3) the patient will have close follow-up, ideally within 24 to 48 hours; and (4) the risks and benefits of discharge have been discussed with the patient.
"HK is a common electrolyte abnormality, and its clinical manifestation may be non-specific. Medications used in the acute setting are limited to shifting potassium and lack robust safety and efficacy data. Moreover, the lack of guidelines has led to much variability in HK treatment," wrote the authors. "This consensus document proposes a HK management and patient disposition protocol for the acute setting, incorporating the best available evidence. A standardized protocol is a significant leap forward on the path to understanding the efficacy and safety of commonly used agents, and this document presents one such protocol."
Further clinical studies are needed to address knowledge gaps and to provide much-needed patient outcomes data for the treatment of HK in the acute setting, they concluded.
"Hyperkalemia management in the emergency department: An expert panel consensus," is published in the Journal of the American College of Emergency Physicians Open (JACEP Open).