Acute Kidney Injury Part 1:
May cause sudden death with no warning features. Symptoms include paraesthesiae, circumoral tingling, muscle weakness, malaise. There may be no clinical signs.
Elevated potassium: absolute level and rate of rise are important. An abrupt rise of 2 mmol e.g. from 4 mmol/l to 6 mmol/l may cause arrhythmias whilst some patients with chronic renal failure tolerate higher levels. Consider level >6mmol/l as potentially dangerous. ECG changes may provide the first clue to hyperkalaemia and its severity. ECG may be NORMAL in presence of dangerous hyperkalaemia .
ECG CHANGES OF HYPERKALAEMIA
- Prolonged PR interval.
- Peaked T waves.
- Widening of QRS interval and flattening/loss of P waves.
- Sine wave proceeding to ventricular fibrillation or asystole.
CAUSES OF HYPERKALAEMIA
1. Reduced excretion:
- Renal failure
• Potassium sparing diuretics: Spironolactone, Triamterene, Amiloride
• ACE inhibitors, angiotensin II antagonists
- Hypoaldosteronism: adrenal insufficiency
2. Shift of K+ from cells:
- Tissue damage: rhabdomyolysis, trauma, burns, haemolysis, internal bleeding
- Drugs: suxamethonium , digoxin, ß-blockers, thiopentone infusion, addiphos
- Others: hyperosmolality, insulin lack, periodic paralysis
3. Excessive intake
- Thrombocytosis, leukocytosis
- Haemolysis: in vitro or sampling
- Delayed analysis