Calcium restores the electrical and chemical gradient of the cardiac myocyte, thus narrowing the QRS.5 Calcium does not decrease serum potassium levels, and its effect is rapid but transient. The dose is one ampule, or 10 mL of 10% calcium chloride solution, with a maximum dose of two ampules or 20 mL. Some authors prefer calcium gluconate to calcium chloride based on the reduced risk of tissue necrosis should it extravasate at the injection site.⁶ Calcium gluconate may also be preferred in pediatric cases and in more chronic, less emergent hyperkalemic patients when a slow infusion is desired. It has about a third the amount of free calcium (13.6 mEq/10 mL for calcium chloride versus 4.6 mEq/10 mL for calcium gluconate).

Critical Decision

What medications should be considered for patients with hyperkalemia to drive potassium into the cell, after the immediate need for intravenous calcium has been determined?

A beta2-agonist, insulin and glucose, in some cases sodium bicarbonate, and saline can be given to shift potassium into cells. Sodium bicarbonate alone does not lower serum potassium in patients with hyperkalemia and is unreliable at best in combination with other agents. It should be reserved for patients who are severely acidemic.^3,7,8 Sodium bicarbonate should not be used in patients with a pH above 7.3 as it is hyperosmolar and will not lower potassium values in the nonacidotic patient. Patients with a pH value below 7.2 or 7.3 will benefit from 100 mL or 50 mL of sodium bicarbonate, respectively.

Nebulized albuterol by face mask begins to take measurable effect after 15 to 20 minutes and lowers the serum potassium level by up to 1 mEq/L, depending on the dose. beta-agonists are safe despite the side effect of tachycardia.^9,10 Insulin, given intravenously in combination with glucose, also results in a similar fall in the potassium level after 20 to 30 minutes and also lowers levels by up to 1 mEq/L. The combination of nebulized albuterol and intravenous insulin with glucose appears to be additive, lowering serum potassium by a mean of 1.21 mEq/L or more.¹¹ Adult hyperkalemic patients who have ECG changes should receive continuous nebulized albuterol and 50 grams of intravenous dextrose plus 10 units of intravenous regular insulin.

Most patients with hyperkalemia have impaired or no renal function. However, even a few hundred milliliters of normal saline can help move potassium intracellularly via the sodium-potassium pump. Prior to the use of saline, the patient’s nephrologist should be consulted and emergent hemodialysis scheduled. For patients with normal or near normal renal function such as those with rhabdomyolysis or tumor lysis syndrome, aggressive saline diuresis supplemented by furosemide may be all that is required to treat the patient’s hyperkalemia, thus avoiding dialysis.