Electrolyte Imbalances: Potassium (K+)

Potassium (K+)

  • Relationship with Sodium (Na+):

    • Potassium has an opposite relationship with sodium.

    • High sodium levels often correlate with low potassium levels.

    • High potassium levels often correlate with low sodium levels.

    • This reciprocal relationship is crucial for fluid balance within cells and the function of sodium-potassium pumps.

  • Location and Concentration:

    • Potassium is primarily found inside the cell in higher concentrations.

    • Sodium, in contrast, has a higher concentration outside the cell.

  • Physiological Roles:

    • Plays a significant role in muscle contraction.

    • Crucial for nerve impulse transmission.

    • Works together with sodium in the sodium-potassium pumps to maintain cell membrane potential and regulate fluid.

    • Imbalances in potassium can lead to severe issues in these vital functions.

  • Normal Reference Range:

    • A normal potassium level is between 3.5 to 5 milliequivalents per liter (mEq/L).

    • This is a very narrow yet critical range, highlighting the precise regulation required for this electrolyte.

Hypokalemia (Low Potassium)

  • Definition: Characterized by low potassium levels in the blood.

  • Primary Causes:

    • Loop Diuretics: Medications like Furosemide cause the kidneys to excrete or "waste" potassium, leading to decreased blood levels. This is a crucial factor to monitor in patients on these drugs.

    • Corticosteroids: These medications can also contribute to lower potassium levels.

    • Excess Insulin: Insulin facilitates the movement of potassium from the bloodstream into the cells. Therefore, too much insulin can drop blood potassium levels.

    • Cushing Syndrome: This condition involves high cortisol levels, which lead to a decrease in potassium and an increase in sodium, consistent with the inverse relationship between these electrolytes.

    • Starvation/Extreme Conditions: Patients experiencing prolonged periods without adequate nutrition can develop hypokalemia.

    • Excessive Potassium Loss: Significant loss of potassium, particularly from gastrointestinal (GI) juices, which are rich in potassium, can cause hypokalemia. Examples include:

      • Severe vomiting.

      • GI suctioning, such as through a nasogastric (NG) tube.

  • Signs and Symptoms (The "Seven L's" Mnemonic):

    • When potassium levels are low, physiological functions tend to be low and slow.

    • 1^{st} L: Lethargy & Confusion: Patients may appear very tired, listless, and disoriented.

    • 2^{nd} L: Low, Shallow Respirations: Hypokalemia can depress respiratory drive, leading to inadequate and shallow breathing.

    • 3^{rd} L: Lethal Cardiac Dysrhythmias: This is a critical and potentially life-threatening symptom. ECG changes indicative of hypokalemia include:

      • ST-segment depression.

      • Flattened or shallow T-waves.

      • Development of a prominent {U} wave (projecting {U} wave).

    • 4^{th} L: Lots of Urine: The kidneys become unable to concentrate urine effectively, leading to frequent urination and polyuria.

    • 5^{th} L: Leg Cramps: Muscle weakness and cramping, particularly in the legs, are common due to potassium's role in muscle function.

    • 6^{th} L: Limp Muscles/Decreased Deep Tendon Reflexes (DTRs): Generalized muscle weakness can progress to flaccid paralysis, and neurological reflexes may be diminished or absent.

    • 7^{th} L: Low Blood Pressure & Heart Rate: The patient may experience hypotension and bradycardia.

Interventions:

* #1 priority = place on continuous cardiac monitor.

  • Administer potassium supplements (oral or V).

  • Hold potassium supplements if urine output is
    ≤30 mL/hr.

* If giving IV potassium, NEVER give via IV push!

  • Always dilute IV potassium and use a programmable infusion pump-too much too quickly can cause cardiac arrest.

  • IV potassium is a vesicant (irritating to veins) that can cause tissue necrosis.

  • If IV infiltration or extravasation occurs, stop the infusion, discontinue the venous access device (VAD), and notify the HCP.

* Encourage intake of potassium-rich foods: Bananas, oranges (or juice), raisins, and potatoes.