Medication Summary
Direct treatment is aimed at stabilizing the myocardium, shifting potassium from the extracellular environment to the intracellular compartment, and promoting the renal excretion and GI loss of potassium.
Electrolyte supplements
Class Summary
These agents are used to treat hyperkalemia and to reduce the risk of ventricular fibrillation caused by hyperkalemia. They act quickly and can be lifesaving, thus they are the first-line treatment for severe hyperkalemia when the ECG shows significant abnormalities (eg, widening of QRS interval, loss of P wave, cardiac arrhythmias). Calcium usually is not indicated when the ECG shows only peaked T waves.
Calcium chloride (Kalcinate)
Calcium increases threshold potential, thus restoring normal gradient between threshold potential and resting membrane potential, which is elevated abnormally in hyperkalemia. One ampule of calcium chloride has approximately 3 times more calcium than calcium gluconate. The onset of action is less than 5 min and lasts about 30-60 minutes. Doses should be titrated with constant monitoring of ECG changes during administration; repeat the dose if ECG changes do not normalize within 3-5 minutes.
Antidotes
Class Summary
Insulin is administered with glucose to facilitate the uptake of glucose into the cell, which results in an intracellular shift of potassium.
Dextrose (D-Glucose)
Glucose and insulin temporarily shift K+ into cells; effects occur within first 30 minutes of administration.
Insulin (Humulin, Humalog, Novolin)
Insulin stimulates cellular uptake of K+ within 20-30 minutes; administer glucose along with insulin to prevent hypoglycemia (monitor blood glucose levels closely).
Alkalinizing agents
Class Summary
These agents increase the pH, which results in a temporary potassium shift from the extracellular to the intracellular environment. These agents enhance the effectiveness of insulin in patients with acidemia.
Sodium bicarbonate (Neut)
Bicarbonate ions neutralize hydrogen ions and raise urinary and blood pH. The onset of action is within minutes and lasts approximately 15-30 minutes. It is only likely to be efficacious if underlying acidosis is present. Monitor blood pH to avoid excess alkalosis.
Use 8.4% solution in adults and children and 4.2% solution in infants.
Beta2-adrenergic agonists
Class Summary
These agents promote cellular reuptake of potassium, possibly via the cyclic gAMP receptor cascade.
Albuterol (Ventolin, Proventil)
Albuterol is an adrenergic agonist that increases the plasma insulin concentration, which may, in turn, help shift K+ into the intracellular space. It lowers K+ levels by 0.5-1.5 mEq/L. Albuterol can be very beneficial in patients with renal failure when fluid overload is a concern. The onset of action is 30 minutes; the duration of action is 2-3 hours.
Diuretics
Class Summary
These agents cause the loss of potassium through the kidney.
Furosemide (Lasix)
Effects are slow and frequently take an hour to begin. Furosemide lowers the potassium level by an inconsistent amount. Large doses may be needed in renal failure.
Ethacrynic acid (Edecrin)
Ethacrynic acid increases the excretion of water by interfering with the chloride-binding cotransport system, which, in turn, inhibits sodium and chloride reabsorption in the ascending loop of Henle and distal renal tubule.
Binding resins
Class Summary
These agents promote exchange of potassium for sodium in GI system.
Sodium polystyrene sulfonate (Kayexalate)
Sodium polystyrene sulfonate exchanges Na+ for K+ and binds it in the gut, primarily in the large intestine, decreasing total body potassium. The onset of action after oral administration ranges from 2-12 hours (longer when administered rectally). It lowers K+ over 1-2 hours, with a duration of action of 4-6 hours. The potassium level drops by approximately 0.5-1 mEq/L. Multiple doses are usually necessary.
Electrolytes
Class Summary
These agents have been successfully used in the treatment of acute SLOW released oral potassium overdose.
Magnesium sulfate
Magnesium sulfate is a nutritional supplement in hyperalimentation; it is a cofactor in enzyme systems involved in neurochemical transmission and muscular excitability. In adults, 60-180 mEq of potassium, 10-30 mEq of magnesium, and 10-40 mmol of phosphate per day may be necessary for an optimum metabolic response. Give intravenously for acute suppression of torsade. Repeat doses are dependent upon continuing the presence of a patellar reflex and adequate respiratory function.
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Widened QRS complexes in hyperkalemia.
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Widened QRS complexes in a patient whose serum potassium level was 7.8 mEq/L.
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ECG of a patient with pretreatment potassium level of 7.8 mEq/L and widened QRS complexes after receiving 1 ampule of calcium chloride. Notice narrowing of QRS complexes and reduction of T waves.
