Surgery
A 33-year-old man is known to have renal impairment, underwent appendectomy for acute appendicitis.
On the first day after surgery, he was complaining of palpitation (see lab result and report). Test Result Normal Value Potassium 6.5 3.5-5.1 mmol/L ECG: Tented T-waves. Which of the following is the most appropriate initial step in management?
Explanation
Core Concept: Severe hyperkalemia (K > 6.5 mEq/L) with concurrent ECG changes (tented T-waves, widened QRS, loss of P wave) is a life-threatening medical emergency due to the high risk of fatal ventricular arrhythmias (V-fib) or asystole.
Clinical Presentation:
- Classic symptoms: Palpitations, muscle weakness, paralysis, or it may be entirely asymptomatic until sudden cardiac arrest.
- ECG changes: Peaked/tented T-waves (earliest sign), prolonged PR interval, widened QRS complex, and eventually a sine-wave pattern.
Diagnosis:
- Diagnostic algorithm: Immediate ECG and stat serum potassium in a patient with renal impairment or tissue breakdown.
- First-line diagnostic plan: 12-lead ECG.
- Gold standard: Serum potassium level.
Management:
- Acute management: Intravenous calcium gluconate (or calcium chloride) is the *first and most critical step* to stabilize the myocardial cell membrane and raise the threshold potential, preventing arrhythmias. It does *not* lower serum potassium. This is immediately followed by intracellular shifting agents (insulin + dextrose, albuterol, sodium bicarbonate) and finally potassium elimination (loop diuretics, GI cation exchangers, or hemodialysis).
- Long-term/Definitive management: Identify and treat the underlying cause of hyperkalemia (e.g., adjust nephrotoxic drugs, manage AKI/CKD, dietary potassium restriction).