21. Rhabdomyolysis

Question 1

Hyperkalaemia emergency management

Answer 1

1. ABCs
   100% O2
   Call for help
2. IV access
   U+E,
   ECG Pulse Ox NIBP
3. Cardiac protection - Myocardial membrane stabilisation
   10mmol 10% calcium gluconate IV over 10min
4. Intracellularly drive K
   - Give Insulin (actarapid) 10iu
   in 50mls 50% dex
   (no dextrose if sugar >14)

5mg Salbutamol nebulisers

4. K Elimination
   Furosemide
   Consider need for CVVHD

Question 2

Complications

Answer 2

1.Hyperkalaemia

Arrythmias / Cardiac arrest

2. Compartment syndrome
3. Acute renal failure
4. DIC
   >72 hours
5. HyperCa

Question 3

2. Compartment syndrome

Answer 3

2. Compartment syndrome

Fluid sequestration
Oedema
Impaired compartment perfusion = Ischaemia & nerve damage

Question 4

3. Acute renal failure

Answer 4

D/T Renal vasoconstriction

Hypovolaemia

Mechanical obstruction from intraluminal cast formation

Direct cytotoxicity from myoglobin haem moieties

Question 5

Management of Rhabdomyolosis

Answer 5

1. Admit HDU / ICU
   Invasive cardiovascular monitoring / Rx
2. Large volume Isotonic fluid therapy
   - aim urine output 200-300m/hr
3. Serial CK measurements
   determine peak
4. If evidence compartment syndrome
   surgical fasciotomies prn
5. IV soda bic
   titrate urinary pH >6.5 -> correct acidosis
   Reduce risk hyperK
   Increase urinary ph
   ?prevent precipitation & degredation of myoglobin in renal tubules

Question 6

Management rhabo continued

Answer 6

Forced alkaline diuresis (e.g. frusemide, mannitol)
increases tubular flow and increases pH to prevent precipitation of myoglobin in tubules

Increase RBF + GFR
Reduce muscle swelling risk compartment
Free radical scav

(despite theoretical benefit no clinical evidence improve morbidity / mortality)

RRT
helps with hyperkalaemia and acidosis
clears low molecular weight renal toxins

Plasma exchange has no demonstrable benefit

Question 7

Causes Rhabdo

Answer 7

Metabolic and endocrine
thyroid storm, phaeochromocytoma, myxoedema, DKA,
HONK

Ischaemia
compartment syndrome, prolonged immobilisation (e.g. coma, drug overdose), prolonged tourniquet use, post aortic clamp operations, reperfusion injuries.

Trauma
crush injury, burns, electrocution
Excessive physical activity
prolonged exertion, prolonged seizures

Infection
viral (e.g. severe influenza), clostridium, persistent high fever

Autoimmune
polymyositis, dermatomyositis

Electrolytes
hypokalaemia, hypophosphatemia

Hyperthermia and hypothermia

Drugs and toxins
hyperthermia toxidromes: sympathomimetics (e.g. cocaine, amphetamines), malignant hyperthermia, serotonin syndrome, neuroleptic malignant syndrome, salicylism
statins / HMG-CoA reductase inhibitors
sedatives (e.g. opiates, alcohol) causing coma/ prolonged immobilisation
myonecrosis from non-depolarising neuromuscular blockers
envenomation (e.g. snake)

Rare genetic disorders (e.g. carbohydrate or lipid metabolic disorders, myopathies