2. Skeletal muscle junction
Results in the leakage of metabolites
Into
bloodstream
Too much activity causes heat
Too much calcium leaking
increases muscle tone

3. The Royal Canberra Hospital
The syndrome was first recognized in Australia in an affected family by Denborough et al. in 1962.
The Royal Canberra Hospital

4. Autosomal dominant inheritance
Mutation at the Ryanodine receptor gene (chromosome 19q13.1)
1:4,500 to 1:60,000 procedures involving general anaesthesia

5. MH Standard test Muscle biopsy
the "caffeine-halothane contracture test“
sensitivity is 97% and the specificity 78%

6. Triggers Onset – one to several hours from exposure
Suxamethonium
ALL volatile agents
SAFE
Nitrous oxide
Intravenous anaesthetics
Non-depolarising muscle relaxants
Local anaesthetic agents

7. Suspicions during G.A. The aftermath (blood toxins)
Rigidity (if not using a muscle relaxant*)
Hypercapnia – indicates catabolism
Tachycardia – indicates high O2 consumption
Mixed acidosis
Then finally hyperthermia - to ~2°C per hour; temperatures up to 42°C (108°F)
The aftermath (blood toxins)
Rhabdomyolysis (breakdown of muscle tissue)
Red-brown decoloration of the urine
Cardiological or neurological evidence of EUC disturbances
Acute renal failure

8. MH ALERT
ANYONE with a family or personal history – no matter how vague
King-Denborough Syndrome
Myopathy-muscle weakness due to muscle cell abnormality)
Short stature
Cryptorchidism (undescended testicles),
Pectus carinatum(a chest wall deformity),
Thoracic lordosis
lumbar kyphosis (reversed curvature of the spine), and
unusual facial characteristics

9. Treatment Three pronged attack
Team A
Remove Trigger
Provide TIVA
Ensure muscle relaxation
Team B
Treatment
Dantrolene
Difficult to mix May need >10 vials & 500mL of solvent
Team C
Symptom relief
Cooling
Diruesis
Other support – whichever team is first available
Call for 2nd anaesthetist
Art line equipment
ABG (syringe & runner)
ICU Liaison
Consult advance MH Flowchart for drugs, defibrillation, blood tests, retrieval, external sources of Dantrolene.

10. Dantrolene
Mortality of malignant hyperthermia fell from 80% in the 1960s to less than 10%.
Formulation: 20mg vial mixed to 60mL
Dose: 2.5mg/kg (initially)
e.g. For 50kg
= 125mg
= 6.25 vials
= 375mL
Double for 100kg
Quadruple for full dose of 10mg/kg over 1 hour.
Need >2 people.

11. Prevention Remove known triggers from room
Choose regional anaesthesia if possible
Choose TIVA (e.g. propofol, opiates, benzodiazepines) for GA
New breathing circuit on machine
Flushing the machine and ventilator with 100% oxygen at maximal gas flows for 20–30 minutes