Rhabdomyolysis

Contents

Rhabdomyolysis is the result of breakdown of muscle tissue, with the subsequent release of muscle products into the bloodstream.

Causes

Trauma – most common
Prolonged immobilisation
Drug reactions – e.g. statins, fibrates, alcohol, ecstacy, heroin, carbon monoxide, neuroleptic malignant syndrome
Infection – coxackie, EBV, influenza
Metabolic disorders
Genetic muscular disorders – e.g. McArdle’s disease, Duchenne’s muscular dystrophy

The breakdown of muscle tissue release several products into the blood, including:

Bloods
- ↑CK > 1000iU/L
- U+E’s – hyperkalaemia
Urine Dipstick
- +ve for haemoglobin, but absence of red cells on microscopy – due to myoglobin

URGENT – treat hyperkalaemia (if >6.5mmol/L, or ECG changes)
- Untreated, it can cause VENTRICULAR FIBRILLATION
  - Other ECG changes include; ‘tented T waves’, flat p waves, increased PR interval, wide QRS – which can get wider and wider, resulting in VT and VF
- Treatment
  - IV calcium gluconate – this provides cardioprotection but does not alter serum potassium concentration
  - Insulin + glucose – e.g. 20U insulin + 50g glucose 50% IV. Insulin is taken up into cells in conjunction with potassium, thus, serum K is lowered
  - Nebulised salbutamol – also moves K into cells
  - Polysytrene sulfonate resin – 15g/8h in water, or can be given as an enema if vomiting present (can cause vomiting)
  - Dialysis – rarely needed
IV fluids
- Reduce the risk of ARF
- Keep urine output at >300ml/hour until myoglobinurea is resolved
- 1.5L/hour may be required
IV sodium bicarbonate
- Can be useful to increase the urine pH >6.5, which makes myoglobin less toxic
With treatment, most patients make a full recovery (as the cause is usually identifiable and resolvable), without any long-term effects