🚨 Hyperkalaemia

Hyperkalaemia is a potentially life-threatening electrolyte disturbance defined as a serum potassium level above 5.0 mmol/L. Severe hyperkalaemia (>6.5 mmol/L) can cause cardiac arrhythmias and sudden cardiac arrest. Prompt recognition and management are essential to prevent fatal outcomes.

Patients may be asymptomatic, or present with non-specific symptoms like muscle weakness, fatigue, or paraesthesia. Cardiac symptoms, such as palpitations or chest pain, are concerning. In severe cases, flaccid paralysis or cardiac arrest can occur. Always consider the patient's underlying conditions and medications.

A: Ensure airway patency. B: Assess respiratory rate and effort. C: Evaluate heart rate, blood pressure, and obtain an immediate 12-lead ECG to look for characteristic changes. D: Assess neurological status for weakness or altered consciousness. E: Look for signs of underlying causes, such as renal failure or rhabdomyolysis.

ECG changes (peaked T waves, prolonged PR interval, widened QRS, absent P waves, sine wave pattern), severe muscle weakness, paralysis, or any signs of cardiac instability (hypotension, bradycardia, arrhythmias) are critical red flags. A rapidly rising potassium level is also highly concerning.

Bedside: 12-lead ECG immediately. Bloods: Urgent serum potassium, urea and electrolytes, creatinine, blood gas (for pH and bicarbonate), full blood count, glucose, cardiac enzymes if indicated. Urine: Urine output monitoring. Consider drug levels if relevant.

Stabilisation of cardiac membrane with intravenous calcium preparation is the first priority if ECG changes are present. Shift potassium intracellularly using intravenous insulin and glucose, or nebulised beta-2 agonists. Remove potassium from the body using loop diuretics, cation-exchange resins, or ultimately dialysis. Address underlying causes.

Any hyperkalaemia with ECG changes, severe hyperkalaemia (>6.5 mmol/L), or rapidly rising potassium levels warrant immediate senior medical review. Patients with refractory hyperkalaemia or severe renal impairment require urgent nephrology consultation and consideration for dialysis. Any cardiac arrest due to hyperkalaemia requires immediate resuscitation.

Always perform an ECG immediately for suspected hyperkalaemia. Calcium gluconate stabilises the myocardium but does not lower potassium. Insulin/glucose is the most effective way to shift potassium intracellularly. Remember the 'C BIG K' mnemonic for management steps (Calcium, Bicarbonate, Insulin, Glucose, Kayexalate).