title: "Hyperkalaemia"
Hyperkalaemia
Hyperkalaemia (K⁺ >5.5 mmol/L) is a medical emergency when severe (>6.5) or with ECG changes. It causes fatal arrhythmias.
Source: Therapeutic Guidelines (eTG) / local hyperkalaemia protocol.
Definition & Severity
| Level | K⁺ (mmol/L) | Risk |
|---|---|---|
| Mild | 5.5-5.9 | Low |
| Moderate | 6.0-6.4 | Moderate |
| Severe | ≥6.5 | High - treat urgently |
| With ECG changes | Any level | Emergency |
Causes
Causes of Hyperkalaemia - MACHINE
- M - Medications (ACEi, ARBs, K⁺-sparing diuretics, NSAIDs)
- A - Acidosis (metabolic acidosis shifts K⁺ out of cells)
- C - Cellular destruction (rhabdomyolysis, tumour lysis, burns, haemolysis)
- H - Hypoaldosteronism (Addison's, type 4 RTA)
- I - Intake (diet, IV fluids with K⁺, blood transfusion)
- N - Nephrons not working (AKI, CKD)
- E - Excretion impaired (renal failure)
ECG Changes
ECG changes progress with increasing K⁺:
| K⁺ Level | ECG Changes |
|---|---|
| 5.5-6.5 | Peaked T waves (tall, narrow, tented) |
| 6.5-7.5 | PR prolongation, flattened P waves |
| 7.5-8.0 | Widened QRS, bradycardia |
| >8.0 | Sine wave pattern, VF, asystole |
Warning
Peaked T waves are the earliest ECG sign. Any ECG changes mandate immediate treatment regardless of K⁺ level.
ECG Examples
Management
1. Protect the Heart (Immediate)
Calcium gluconate 10% 10mL IV over 2-5 minutes - stabilises cardiac membrane. Does NOT lower K⁺. Effect lasts 30-60 min. Repeat if ECG changes persist.
Source: Therapeutic Guidelines (eTG) / local hyperkalaemia protocol.
2. Shift K⁺ into Cells (Works in 15-30 min)
| Treatment | Dose | Onset | Duration |
|---|---|---|---|
| Insulin + Dextrose | 10 units Actrapid + 50mL 50% dextrose | 15 min | 4-6 hours |
| Salbutamol nebulised | 10-20 mg | 15-30 min | 2 hours |
| Sodium bicarbonate | 50 mmol (50mL 8.4%) | 30 min | Variable |
Clinical Pearl
Always give dextrose with insulin to prevent hypoglycaemia. Check BSL at 30 min, 1h, and 2h post-treatment.
3. Remove K⁺ from Body (Definitive)
| Treatment | Mechanism | Notes |
|---|---|---|
| Loop diuretics | Increase renal excretion | If kidneys working |
| Resonium (calcium polystyrene) | GI K⁺ binding | 15-30g PO/PR, slow onset |
| Dialysis | Removes K⁺ directly | Most effective, for severe/refractory |
4. Stop Contributing Factors
- Stop K⁺-containing fluids
- Stop ACEi, ARBs, K⁺-sparing diuretics
- Stop NSAIDs
- Treat underlying cause (sepsis, AKI, acidosis)
Treatment Summary
Severe or ECG changes:
- Calcium gluconate 10% 10mL IV (cardioprotection)
- Insulin 10 units + 50% dextrose 50mL IV (shift)
- Salbutamol 10-20mg nebulised (shift)
- Consider sodium bicarbonate if acidotic (shift)
- Arrange dialysis if renal failure (remove)
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