Armando Hasudungan
Biology and Medicine videos

↓↑Potassium (Hyperkalaemia and Hypokalaemia)

Overview Potassium (K+) is an important ion in the body. K+ is found mainly intracellularly (inside the cells) whereas sodium (Na+) is found extracellularly (outside the cells). Serum Potassium: 3.5mmol/L – 5.0mmol/L Serum Sodium: Therefore: Hyperkalaemia: >5mmol/L Hypokalaemia: <3.5mmol/L As the pH rises , K+ is shifted intracellularly and the serum levels falls; conversely when […]

Overview Potassium (K+) is an important ion in the body. K+ is found mainly intracellularly (inside the cells) whereas sodium (Na+) is found extracellularly (outside the cells).

  • Serum Potassium: 3.5mmol/L – 5.0mmol/L
  • Serum Sodium:

Therefore:

  • Hyperkalaemia: >5mmol/L
  • Hypokalaemia: <3.5mmol/L

As the pH rises , K+ is shifted intracellularly and the serum levels falls; conversely when serum pH decreases, intracellular K+ shits extracellularly into the vascular space and so the serum level increases. This is because H+ and K+ are both positive and it is important to have normal +ions levels in the serum to maintain a gradient across the cell membrane to maintain the excitability of nerve and muscle cells, including the myocardium.

Causes of Hyperkalaemia

  • Excessive intake
  • Increased production
    • Haemolysis
    • Rhabdomyolysis
    • Intense physical activity
    • Burns
    • Tumour lysis syndrome
  • Shift from intracellular to extracellular fluid
    • Acidosis
    • Insulin deficiency/resistance
    • Medications
      • β-blocker
      • Suxamethonium
      • Digoxin
      • Spironolactone
    • Hyperkalaemic periodic paralysis
  • Decreased excretion
    • Renal failure
    • Addison’s disease
    • Medications
      • Potassium sparing diuretics
      • ACE inhibitors
      • NSAIDs
      • Trimethoprim, cyclosporin, tacrolimus

Signs and symptoms

  • Non-specific
  • Generalised muscle weakness
  • Respiratory depression
  • Ascending paralysis
  • Palpitations, Arrhythmia, Cardiac arrest
    • ECG CHANGES:

 

Management – nonpharmacological

  • ECG
  • ABCD
  • Check serum potassium

Management – pharmacological

  • IV Frusemide (provided patient normal urine output)
  • IV Calcium chloride or Calcium gluconate
  • Drive K+ into the cell
    • Insulin + Glucose
    • Salbutamol
    • Sodium bicarbonate – if acidotic
  • Monitor serum K+ every hour
  • Eliminate K+ from the body
    • Calcium Resonium (this is slow)
    • Dialysis (last line)
Pharmacology Calcium Gluconate is a myocardium stabiliser and is cardioprotective.  Side effects: Bradycardia, hypotension and peripheral vasodilation.
Pharmacology Calcium Resonium is a large insoluble molecule that binds to K+ in the large intestine, where it is excreted in faeces. Side effects:

 

MANAGEMENT OF HYPERKALAEMIA DEPENDING ON SEVERITY
Mild Moderate  Severe
Calcium Resonium IV Frusemide IV Frusemide
Calcium Resonium Calcium gluconate/Calcium chloride
Insulin + Dextrose/N.Saline Insulin + Dextrose/N.Saline
Salbutamol Salbutamol

Complications of Hyperkalaemia

  • Cardiac arrest
  • Weakness
  • Paraesthesiae
  • Decreased reflexes
  • Ascending paralysis

Hypokalaemia

Defined as potassium <3.5mmol’L

Signs and symptoms

  • Generalised muscle weakness
  • Respiratory depression
  • Ascending paralysis
  • Ileus, constipation
  • Palpitations, Arrhythmia, Cardiac arrest
  • Nephrogenic diabetes insipidus (characterised by polyuria and polydipsia)

Management – nonpharmacological

  • ECG
  • ABCD
  • Check serum potassium

Management – pharmacological

  • Chlorvescent – Given STAT
  • Slow K
  • Potassium Chloride (KCl) IV given in 10mmol in 100ml of normal saline
  • Check serum potassium

ECG findings

  • Peaked P waves
  • T wave flattening and inversion
  • U waves

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