Potassium

Potassium

• Major ICF cation necessary for
  • Transmission and conduction of nerve and muscle impulses
  • Cellular growth
  • Maintenance of cardiac rhythms
  • Acid-base balance
• Sources
  • Fruits and vegetables (bananas and oranges)
  • Salt substitutes
  • Potassium medications (PO, IV)
• Regulated by kidneys
• Hyperkalemia
  • High serum potassium caused by
    • Impaired renal excretion
    • Shift from ICF to ECF
    • Massive intake
  • Most common in renal failure
  • Manifestations
    • Cardiac dysrhythmias
    • Cramping leg pain
    • Weak or paralyzed skeletal muscles
    • Abdominal cramping or diarrhea
  • ECG effects of Hyperkalemia

• • • The most clinically significant manifestations of hyperkalemia are the disturbances in cardiac conduction.
    • Cardiac depolarization is decreased, leading to flattening of the P wave and widening of the QRS complex.
    • Repolarization occurs more rapidly, resulting in shortening of the QT interval and causing the T wave to be narrower and more peaked.
    • Ventricular fibrillation or cardiac standstill may occur.
  • Nursing diagnosis
    • Risk for electrolyte imbalance related to excessive retention or cellular release of potassium
    • Risk for activity intolerance related to muscle weakness
    • Risk for injury related to muscle weakness and seizures
    • Potential complication: dysrhythmias
  • Nursing implementation
    • Eliminate oral and parenteral K intake
    • Increase elimination of K (diuretics, dialysis, Kayexalate)
    • Force K from ECF to ICF by IV insulin and a b-adrenergic agonist or sodium bicarbonate
    • Reverse membrane effects of elevated ECF potassium by administering calcium gluconate IV
• Hypokalemia
  • Low serum potassium caused by
    • Increased loss of K+ via the kidneys or gastrointestinal tract
    • Increased shift of K+ from ECF to ICF
    • Dietary K+ deficiency (rare)
  • Manifestations
    • Cardiac most serious
    • Skeletal muscle weakness (legs)
    • Weakness of respiratory muscles
    • Decreased GI motility
    • Hyperglycemia
  • ECG effects of Hypokalemia