A 58-year-old man with type 2 diabetes mellitus and stage 4 chronic kidney disease (eGFR 22 mL/min/1.73 m²) presents to the emergency department with palpitations and mild dyspnea. He reports taking lisinopril and spironolactone for hypertension and proteinuria. On examination, heart rate is 68/min with an irregular rhythm. Serum potassium is 7.2 mEq/L. ECG shows peaked T waves, prolonged PR interval, and widened QRS complex. What is the most appropriate immediate management?

Explanation

## Acute Management of Severe Hyperkalemia with ECG Changes **Key Point:** Severe hyperkalemia (K⁺ > 6.5 mEq/L) with ECG changes is a medical emergency requiring immediate stabilization of the cardiac membrane before attempting potassium removal. ### Mechanism of ECG Changes in Hyperkalemia Hyperkalemia depolarizes the resting membrane potential, causing: 1. Peaked T waves (earliest sign) 2. Prolonged PR interval and widened QRS (conduction delay) 3. Loss of P wave (atrial standstill) 4. Sine wave pattern (pre-arrest rhythm) ### Immediate Management Strategy **Step 1: Membrane Stabilization (Cardioprotection)** - **Intravenous calcium gluconate 10% (10–20 mL over 2–5 minutes)** - Mechanism: Raises the threshold potential, opposing hyperkalemia's depolarizing effect - Onset: 1–3 minutes - Effect: Does NOT lower K⁺, but prevents arrhythmias - Can repeat every 5 minutes if ECG changes persist - **This is the FIRST step in symptomatic/ECG-positive hyperkalemia** **Step 2: Shift K⁺ Intracellularly (Potassium Redistribution)** - **Insulin (10 units IV) + Dextrose (25 g IV as 50% dextrose)** - Mechanism: Insulin drives K⁺ into cells via Na⁺-K⁺-ATPase - Onset: 10–20 minutes - Effect: Lowers serum K⁺ by 0.5–1.2 mEq/L - Duration: 4–6 hours - **Dextrose is essential to prevent hypoglycemia** (especially in diabetics) **Step 3: Remove K⁺ from Body (Definitive)** - Diuretics (if euvolemic) - Potassium-binding resins (sodium polystyrene sulfonate, patiromer) - Dialysis (if renal failure or refractory) ### Timeline for This Patient 1. **Immediate (0–5 min):** IV calcium gluconate → stabilize ECG 2. **5–10 min:** IV insulin + dextrose → shift K⁺ in 3. **30–60 min:** Initiate dialysis (definitive in CKD stage 4) **Clinical Pearl:** Calcium gluconate is the ONLY agent that does not lower serum K⁺ but is the most critical in symptomatic hyperkalemia because it buys time for other therapies to work. **High-Yield:** The sequence is **Calcium → Insulin/Dextrose → Removal**. Never skip calcium in ECG-positive cases. ### Why Dialysis Is Not First-Line Here Although this patient has CKD stage 4, dialysis is initiated AFTER acute stabilization because: - Takes 30–60 minutes to set up - Calcium and insulin work within minutes - Dialysis is reserved for refractory hyperkalemia or when medical therapy fails [cite:Harrison 21e Ch 280]