Succinylcholine = Suxamethonium chloride
Mnemonic : SSSS
- FaSt dissociation at receptors (Therefore Short acting )
Mnemonic : DND
- Not reversed by Neostigmine
- No fade or Post tetanic stimulation.
- Respiratory Alkalosis
Antagonised by : Acidosis and NDMR
Repeated use - causes Phase II block (similar to NDMR) -- (MCQ)
Other points about Sch :
- Onset within 30 sec --- lasts 10-12 mins.
- Bradycardia in children (especially after 2nd dose) (MCQ)
- All presures are increased ( BP , ICP , IOP , Intra gastric )
- Enzyme metabolism - by PseudoCholinestrase (= plasma = Butyrylcholinesterase) (read below in short about Cholinestrases )
Dibucaine Number :
- The Dibucaine Number is a measure of the qualitative activity of Pseudocholinesterase and is the percentage of inhibition of the enzyme by the local anesthetic Dibucaine. Normally 75 - 85 % inhibition , But if homozygous defficiency - then 30%
- It is used to differentiate individuals who have substitution mutations of the Butrylcholinesterase enzyme.
Side effects :
- Increase K+ (especially after Burns , spinal cord injury , stroke , cerebral palsy )
Therefore Sch is Avoided 48hrs - 9months after acute injury.
- Post Op muscular pain which can be decreased by :
1. Self Taming (Pretreatment with small (10 mg) doses of succinylcholine)
2. Precurarization (NDMR + Sch)
- Malignant Hyperthermia
- Sch is the MC drug which causes Malignant Hyperthermia.
- All Fluranated inhalational anaesthetics & Lignocaine are other drugs which can cause Malignant Hyperthermia.
- Allergy - releases histamine.
- Contraindicated in Myotonic Dystrophy : as it causes severe muscle rigidity , preventing respiration and intubation.
- Can cause Masseter spasm in children.
NeuroMuscular monitoring (Adductor Pollicis , Ulnar Nerve) (No use in Sch block)
- TOF (Train of 4)
- PTC ( Post tetanic count )
- DBS ( Dual burst stimulation )
- True : RBC and Grey Matter.
- Pseudo/False : Liver and Plasma.