Suxamethonium
(Scoline) Apnoea
Dr S Spijkerman
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.
1.
2.
NB: Mivacurium is also broken down by pCE and should be avoided in
these patients.
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
Clinical presentation
• Prolonged apnoea and inability to
move after standard dose of
suxamethonium
• Patient may be aware, thus may
present with tachycardia,
hypertension
DDx delayed awakening:
Drugs
Benzodiazepine premedication
Opioid overdose intra-operatively
Insufficient reversal of nondepolarising
muscle relaxants
Suxamethonium apnoea
Failure to discontinue anaesthetic vapour
Endocrine
Pre-operative alcohol intoxication
Severe hypothyroidism
Hypoglycaemia
Diabetic keto-acidosis (DKA), hyper osmotic
nonketotic coma (HONK)
Addison’s crisis
DDx (cont)
Electrolyte
disturbances
Acid-base
disturbances
Hyponatraemia
Hypocalcaemia
Hypermagnesaemia (magnesium sulphate
treatment etc)
Hypercapnoea (“Carbon dioxide narcosis”) – due to
hypoventilation
Hypocapnoea (no drive for breathing) – due to
hyperventilation
Hypothermia
IntraCerebro-vascular incident
operative
Myocardial infarction
complications
Undiagnosed
muscle
diseases
Treatment of scoline apnoea
Treat apnoea
Prevent awareness
Exclude differential diagnosis
Fresh frozen plasma/whole
blood
Recombinant pCE
Confirm scoline apnoea
If scoline apnoea confirmed
Mechanical ventilation until
normal muscle strength returns
Continue anaesthesia with
inhalant or sedate well with
benzodiazepines
See table 3
Contains pCE and will speed
recovery BUT risk of infections
like HIV too high, thus NOT
recommended
Very expensive. Cheaper to treat
symptomatically
 pCE activity
 dibucaine or fluoride number
Council patient and family
members
Medic alert bracelet for patient
Test family members
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 = 4060%).
In the same way a fluoride number can be determined