Normal Serum Level: 3.5-5 mEq/L
Daily Sodium requirement: 1-2 mEq/kg

Hyperkalemia ( >5 mEq/L)

Causes : Renal failure, ACE inhibitor, mineralocorticoid deficiency, PRBC transfusion, Acidosis, low insulin state, Beta blocker, Rhabdomyolysis, hemolysis

Signs: Nausea, vomiting and paresthesias or nonspecific findings of muscle weakness (skeletal, respiratory), fatigue and ileus.

Note: Factitious or pseudohyperkalemia occur because of the practice of squeezing of extremities during phlebotomy or blood sampled from a limb being infused with potassium-containing fluid or hemolysis of a standing sample. Thrombocytosis and leukocytosis can also lead to false elevation of serum potassium levels.

ECG Changes:

  • Peaked T waves
  • P wave widening/flattening, PR prolongation
  • Bradyarrhythmias: sinus bradycardia, high-grade AV block with slow junctional and ventricular escape rhythms, slow AF
  • Conduction blocks (bundle branch block, fascicular blocks)
  • QRS widening with bizarre QRS morphology
Potassium Level (mmol/L) ECG changes
5.5-6.5 Peaked T waves
6.5-7.0 P wave widening/flattening
PR Prolongation
P waves eventually disappear
7.0-9.0 Sinus bradycardia, High grade AV block, Prolonged QRS interval
>9.0 Sine wave appearance
Asystole
Ventricular fibrilation

Managment:

  • Prompt discontinuation of potassium containing fluids and  medications that lead to hyperkalemia.
  • Stabalize the myocardial cell membrane to prevent cardiac arrhythmia
    • IV 10% calcium gluconate
      • 0.5-1mL/kg over 5-10 minutes under cardiac monitoring (Watch for bradycardia, discontinue if it happens)
  • Enhance cellular uptake of potassium:
    • Asthalin/Salbutamol nebulization
    • Regular insulin and glucose IV: 0.3 U regular insulin/g glucose over 2 hours
    • Sodium bicarbonate IV
      • 1-2 mEq/kg body weight over 20-30 minutes

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