How to rescue hyperkalemia

Written by Wei Shi Liang
Intensive Care Unit
Updated on August 31, 2024
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Hyperkalemia must be dealt with immediately once it occurs. The usual treatments in clinical settings include promoting potassium excretion using furosemide or other loop diuretics to maximize renal potassium excretion, or using oral or rectal potassium-eliminating agents. For life-threatening hyperkalemia with serum potassium levels greater than 6.5 mmol/L, hemodialysis is necessary. Another approach is to facilitate the shift of potassium into cells, which is done through the administration of insulin with glucose, or sodium bicarbonate along with calcium gluconate that helps protect the myocardium, thus providing treatment and protective measures for hyperkalemia.

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Written by Wang Li Bing
Intensive Care Medicine Department
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How is hyperkalemia treated?

Hyperkalemia must be handled immediately after it occurs, otherwise it can cause malignant arrhythmias and even endanger life. The first step is to stop potassium supplements, such as potassium chloride sustained-release tablets; the second step is to stop potassium-sparing diuretics, such as spironolactone and other drugs. We can administer calcium intravenously to antagonize the toxic effects of high potassium on the heart. Additionally, we can use high glucose with insulin and intravenously drip sodium bicarbonate, which can promote the movement of potassium into cells. We can also use diuretics to excrete potassium through urine. If the treatment effect is poor after medication, we can use bedside hemodialysis to reduce blood potassium.

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Written by Wei Shi Liang
Intensive Care Unit
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The impact of hyperkalemia on the heart

The effects of hyperkalemia on the heart mainly manifest in the following ways: First, it affects the excitability of the myocardium, as hyperkalemia can cause reduced or even absent myocardial excitability; second, it impacts myocardial conductivity. In hyperkalemia, due to the reduced resting potential, the amplitude and speed of the action potential's phase zero decrease, leading to slowed excitability spread and reduced conductivity; third, it influences the automaticity of the myocardium. In hyperkalemia, due to slowed automatic depolarization, the automaticity is reduced. Additionally, hyperkalemia produces characteristic changes in the electrocardiogram, such as depression or disappearance of the P wave, prolongation of the PR interval, widening of the S wave, and narrowing and peaking of the T wave, which are the main changes in the electrocardiogram due to hyperkalemia.

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Written by Wei Shi Liang
Intensive Care Unit
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The difference between hyperkalemia and hypokalemia.

Hypokalemia refers to a serum potassium concentration lower than 3.5mmol/L, and its clinical manifestations are diverse. The most life-threatening symptoms involve the cardiac conduction system and the neuromuscular system. Mild hypokalemia shows on an electrocardiogram as flattened T waves and the appearance of U waves, while severe hypokalemia can lead to fatal arrhythmias, such as torsades de pointes and ventricular fibrillation. In terms of the neuromuscular system, the most prominent symptom of hypokalemia is the loss of tone in smooth muscles and flaccid paralysis in skeletal muscles, which, when involving respiratory muscles, can lead to respiratory failure. Hyperkalemia, on the other hand, refers to a serum potassium concentration exceeding 5.5mmol/L, mainly presenting clinical symptoms in cardiac and neuromuscular conduction. Severe cases can cause bradycardia, atrioventricular conduction block, and even sinus arrest. Mild hyperkalemia, with levels between 5.5 to 6.0mmol/L, shows on an electrocardiogram as peaked T waves. As hyperkalemia continues to increase, it can lead to lengthening of the PR interval or disappearance of the P wave, QRS widening, and eventually cardiac arrest. Regarding the neuromuscular system, the clinical manifestations of hyperkalemia are very similar to those of hypokalemia, including weakness and paralysis of skeletal and smooth muscles.

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Written by Wei Shi Liang
Intensive Care Unit
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Common Causes of Hyperkalemia

Hyperkalemia is when the serum potassium concentration exceeds 5.5 millimoles per liter. Common causes include excessive potassium intake and large doses of potassium salts, which can lead to hyperkalemia, as well as the use of stored blood. Another cause is reduced potassium excretion; in patients with renal insufficiency, reduced urine output or anuria leads to decreased renal potassium excretion. If potassium supplementation is inappropriate at this time, or if potassium-sparing diuretics are used, severe hyperkalemia can occur. Another scenario is the leakage of intracellular potassium during respiratory and metabolic acidosis, where sodium ion exchange occurs in cells, hydrogen ions enter the cells, and potassium ions leak out to the extracellular space, which can lead to increased blood potassium. These are the common causes of hyperkalemia.

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Principles of treatment for hyperkalemia

First, to counteract the cardiac inhibitory effects of potassium, calcium salts can be injected, and sodium bicarbonate can be used to alkalinize the blood. Then, an infusion of hypertonic glucose and insulin can be administered to promote the internal movement of potassium ions. Secondly, to promote the excretion of potassium, diuretics can be used. The second method involves the use of cation exchange resins and sorbitol. The third method employs dialysis therapy, which can include both hemodialysis and peritoneal dialysis. The fourth method is to reduce the sources of potassium, stop a high potassium diet or the use of potassium-containing drugs. In cases of severe hyperkalemia, where there is a life-threatening emergency, urgent measures should be taken, primarily the intravenous administration of calcium ion antagonists to counteract the cardiac toxicity of potassium. In cases of severe arrhythmias or even cardiac arrest, emergency installation of a pacemaker or defibrillation can be carried out, and respiratory muscle paralysis may require ventilatory support. (Medication use should be under the guidance of a doctor)