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Potassium Imbalances

5 min read

References:

  1. Saunders Comprehensive Review for the NCLEX-RN Examination, 9th Edition, ISBN 978-032-37-9530-2, by Linda Anne Silvestri, Angela E. Silvestri, and Jessica Grimm (Ch. 8, pp. 88-105)

Hypokalemia

Normal Serum Potassium Level: 3.5 to 5.0 mEq/L (3.5 to 5.0 mmol/L)

Hypokalemia is a serum potassium deficiency, dropping below the lower threshold of 3.5 mEq/L. This is a life-threatening condition as every body system becomes affected. It may be caused by:

  1. Actual loss of potassium:
    • Excessive use of medications such as diuretics, corticosteroids, or inhaled albuterol
    • Increased secretion of aldosterone, such as in Cushing’s syndrome: aldosterone saves sodium by excreting potassium in its place
    • Vomiting, diarrhea
    • Wound drainage, particularly when gastrointestinal
    • Prolonged nasogastric suction
    • Excessive diaphoresis (abnormal sweating)
    • Kidney disease impairing potassium reabsorption
  2. Inadequate intake of potassium: from fasting or being on NPO status.
  3. Movement of potassium from extracellular to intracellular spaces:
    • Alkalosis
    • Hyperinsulinism
  4. Dilution of serum potassium:
    • Water intoxication
    • IV therapy with potassium-deficient solutions

Assessment

  1. Cardiovascular:
    • Thready, weak, irregular pulse; weak peripheral pulses
    • Orthostatic hypotension
    • Dysrhythmias
  2. Respiratory: shallow, ineffective respirations that result from profound muscle weakness of the muscles of respiration. This produces diminished breath sounds
  3. Neuromuscular:
    • Anxiety, lethargy, confusion, coma
    • Skeletal muscle weakness, leg cramps, deep tendon hyporeflexia, loss of tactile discrimination, and paresthesias
  4. Gastrointestinal: decreased motility, hypoactive to absent bowel sounds; paralytic ileus
  5. Laboratory Findings:
    • Potassium studies show a level of <3.5 mEq/L
    • Electrocardiogram changes: ST depression; shallow, flat, or inverted T waves; and prominent U waves

Analyzing Cues

A client with gastroenteritis has been vomiting and having diarrhea for the past 3 days. On admission to the hospital, the client complains of weakness and some leg and abdominal cramping. The client’s respirations are shallow and the pulse is thready. The client’s cardiac rhythm on the monitor screen shows an additional prominent wave following each T wave, indicating the presence of U waves. The nurse considers the client’s health problem, the effects and implications of losing fluid through vomiting and diarrhea for 3 days, analyzes the client cues, and interprets these cues as indicating an electrolyte imbalance, specifically hypokalemia.

Interventions

Monitor the patient’s potassium level. Administer potassium supplements orally or intravenously as prescribed.

  • Oral potassium supplements may cause nausea and vomiting and should not be taken on an empty stomach. If the client complains of abdominal pain, distention, nausea, vomiting, diarrhea, or gastrointestinal bleeding, the supplement may need to be discontinued.
  • Liquid potassium chloride can also be used, but has an unpleasant taste, and should be taken with juice or other liquids.
  • Intravenous potassium is never given via IVP, IM, or SC. Use an infusion pump. A dilution of not more than 1 mEq/dL (1 mmol/dL) is recommended. Potassium instilled into IV bags should be rotated and inverted to ensure distribution of potassium, and properly labeled.
    • Infusion rate should never exceed 20 mEq/hr and is recommended to be infused at around 5 to 10 mEq/hr. Anything more than 10 mEq/hr warrants cardiac monitoring.
    • Potassium infusion can cause phlebitis; the nurse should frequently assess the IV site for signs of phlebitis or infiltration. Infusion should be stopped immediately if complications arise. Potassium chloride can act as a vesicant and extravasation may result in local tissue necrosis.
    • Rapid administration of potassium can result in cardiac arrest.
    • Assess the patient’s renal function prior to administering potassium. Monitor I&O during administration.

Potassium Replacement via IV

Potassium replacement is safest when infused through a central line due to the high incidence of IV infiltration. Potassium is never administered by IV push, intramuscular, or subcutaneous routes. IV potassium is always diluted and administered using an infusion device!

Hyperkalemia

Hyperkalemia is a serum potassium level that exceeds 5.0 mEq/L (5.0 mmol/L). This may be caused by:

  1. Excessive potassium intake: overingestion or administration of potassium-containing foods or medications, e.g. potassium chloride or salt substitutes.
  2. Decreased potassium excretion: from potassium-sparing (retaining) diuretics, kidney disease, or adrenal insufficiency, such as in Addison’s disease.
  3. Movement of potassium from the intracellular to extracellular fluid as a result of tissue damage, acidosis, hyperuricemia, or hypercatabolism.

Potassium imbalance can cause life-threatening cardiac dysrhythmias. Monitor the client closely.

Assessment

  1. Cardiovascular:
    • Slow, weak, irregular heart rate
    • Decreased blood pressure
  2. Respiratory: profound weakness of the skeletal muscles leading to respiratory failure
  3. Neuromuscular:
    • Early manifestations: muscle twitches, cramps, paresthesias (tingling and burning followed by numbness in the extremities and around the mouth)
    • Late manifestations: profound weakness e.g. ascending flaccid paralysis in the arms and legs (trunk, head, and respiratory muscles become affected when a lethal potassium level is reached)
  4. Gastrointestinal:
    • Increased motility; hyperactive bowel sounds; resultant diarrhea
  5. Laboratory Findings:
    • Potassium studies show a level of >5.0 mEq/L
    • Electrocardiogram changes: tall peaked T waves, flat P waves, widened QRS complexes, and prolonged PR intervals.

Interventions

Terminate the source of excessive potassium as soon as possible and continue monitoring the patient’s potassium levels.

  • Discontinue IV potassium (KVO) and withhold oral potassium supplements. Initiate a potassium-restricted diet. Instruct the patient against the use of potassium-containing substances and salt substitutes.
  • Potassium-excreting diuretics may be administered for patients without renal damage. Monitor the patient’s potassium levels closely when taking these medications.
  • If renal function is impaired, sodium polystyrene sulfonate (oral or rectal) is a cation-exchange resin that promotes the reabsorption of sodium and excretion of potassium.
  • Dialysis is used for severe hypokalemia. To avert myocardial excitability from severe hyperkalemia, IV calcium may be given.
  • IV hypertonic glucose with insulin moves excess potassium into cells.
  • If a patient with a potassium imbalance is receiving a blood transfusion, use fresh blood if possible. Transfusions of stored blood may elevate the potassium levels due to the breakdown of older blood cells, releasing potassium.
  • Teach the client to avoid foods high in potassium: all meats, fish, soy products, veggie burgers, vegetables, fruits, milk and yogurt, and nuts.

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