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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 = E1 U .
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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. 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)
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 = 40-60%). In the same way a fluoride number can be determined