1. Suxamethonium (Scoline) Apnoea
Dr S Spijkerman

2. Pathophysiology Suxamethonium is broken down by pCE
Inherited abnormal genetic variant of pCE (autosomal recessive)
Prolonged apnoea after a standard dose of suxamethonium
Several variations:
normal pCE enzyme gene = E1U.
E1a (a = abnormal)
(E1uE1a) recovery time from suxamethonium < 30 minutes
(E1aE1a) recovery time from suxamethonium >2 hours
3. E1f (the fluoride pCE)
4. E1s (silent) → little pCE activity →recovery from suxamethonium
can take >> 3 hours.
NB: Mivacurium is also broken down by pCE and should be avoided in these patients.

3. Acquired causes of decreased pCE activity
(NB: These causes prolong the effect of suxamethonium by minutes
and not by hours like the inherited types)
Pregnancy (dilutional effect due to increased water component)
Newborns (dilutional effect and immature liver, thus decreased pCE synthesis)
Liver diseases
Malnutrition
Severe hypothyroidism
Plasmapheresis

4. Clinical presentation
Prolonged apnoea and inability to move after standard dose of suxamethonium
Patient may be aware, thus may present with tachycardia, hypertension

5. DDx delayed awakening:
Drugs
Benzodiazepine premedication
Opioid overdose intra-operatively
Insufficient reversal of nondepolarising muscle relaxants
Suxamethonium apnoea
Failure to discontinue anaesthetic vapour
Pre-operative alcohol intoxication
Endocrine
Severe hypothyroidism
Hypoglycaemia
Diabetic keto-acidosis (DKA), hyper osmotic nonketotic coma (HONK)
Addison’s crisis

6. DDx (cont) Electrolyte disturbances Hyponatraemia Hypocalcaemia
Hypermagnesaemia (magnesium sulphate treatment etc)
Acid-base disturbances
Hypercapnoea (“Carbon dioxide narcosis”) – due to hypoventilation
Hypocapnoea (no drive for breathing) – due to hyperventilation
Hypothermia
Intra- operative complications
Cerebro-vascular incident
Myocardial infarction
Undiagnosed muscle diseases

7. Treatment of scoline apnoea
Treat apnoea
Mechanical ventilation until normal muscle strength returns
Prevent awareness
Continue anaesthesia with inhalant or sedate well with benzodiazepines
Exclude differential diagnosis
See table 3
Fresh frozen plasma/whole blood
Contains pCE and will speed recovery BUT risk of infections like HIV too high, thus NOT recommended
Recombinant pCE
Very expensive. Cheaper to treat symptomatically
Confirm scoline apnoea
pCE activity
dibucaine or fluoride number
If scoline apnoea confirmed
Council patient and family members
Medic alert bracelet for patient
Test family members

8. Dibucaine is a local anaesthetic that inhibits the activity of pCE
Dibucaine is a local anaesthetic that inhibits the activity of pCE. The normal gene is inhibited by 80% (dibucaine number = 80%), atypical gene by 20% (dibucaine number = 20%) and heterozygous gene by 40-60% (dibucaine number = %). In the same way a fluoride number can be determined