Overview
Hyperkalaemia, or an increased serum potassium concentration of >5mmol/L, shortens action potentials and reduces conduction velocity in cardiac myocytes.
Pathogenesis
Causes of Hyperkalaemia
Factitious
- Haemolysis (e.g. poor collection, delay in lab processing)
- Leukocytosis / thrombocytosis
Increased Intake / Production
- Exogenous administration - massive transfusion, potassium supplements, TPN
- Endogenous production - rhabdomyolysis
Reduced Excretion
- Renal failure - acute or chronic
- Medications - NSAIDs, ACE inhibitors, ARBs, spironolactone, trimethoprim
- Addison's
Compartmental Shift
- Type 4 renal tubular acidosis
- Metabolic acidosis
- Hyperglycaemia
- Beta blockers
- Trauma / burns
Manifestations
Clinical Features
- Paraesthesia
- Flaccid paralysis
- Hypotension
- Bradycardia
- Arrhythmia
ECG Findings
Mild
- Tall, tented T waves
Moderate
- Reduction in P wave height
- Long PR interval
Severe
- Short QT interval
- Widening of QRS complex
- Sine wave QRS pattern
Life-Threatening
- Asystole
Diagnosis
Severity of Hyperkalaemia
- Mild - 5.0 - 6.5 mmol/L
- Moderate - 6.5 - 7.0 mmol/L
- Severe - >7.0 mmol/L
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