Suxamethonium Apnoea
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Transcript Suxamethonium Apnoea
Suxamethonium
(Scoline) Apnoea
Dr S Spijkerman
Pathophysiology
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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.
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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