Neuromuscular Blockade and Paralysis Flashcards
(27 cards)
How can muscle force be increased
- The recruitment of multiple muscle fibres
- The summation of increased firing rates of an action potential on a single fibre
Why can neuromuscular blockades be useful
Surgery
Preventing muscle contractions (pathology)
Muscle relaxation without general anaesthesia
Cosmetic Surgery
What order do neuromuscular blockades affect patients
Extrinsic eye muscles first, small muscles of face and hands, muscles of pharynx then respiratory muscles last
How do neuromuscular blockades work
Slow methodical paralysis in skeletal muscle
Can those who receive neuromuscular blockades experience pain
Yes.
What ways can neuromuscular transmission be blocked
By blocking one of 3 processes
- Neurotransmitter Synthesis/Uptake
- Release
- Receptor
Increasing
- Reuptake
How does synthesis blocking of acetyl choline work
By inhibiting the choline carrier that takes choline and acetate back into the cell
**Hemicholonium
Clinical Relevance of ACh Synthesis Blocking
Not clinically useful it is slow to activate and slow to reverse
How does release blocking of Acetylcholine work to cause a neuromuscular blockade
Alters the exocytosis of the vesicles and blocks neurotransmitter release
An example of something that affects neurotransmitter release to cause a Neuromuscular blockade
Botox, Black widow venom (Latrotoxin)
Which mechanism to non-/depolarising agents affect
Receptor blocking to cause a neuromuscular blockade
How does reuptake increase/Inactivation of Acetylcholine work to cause a neuromuscular blockade
Acetylcholinersterase is inhibited so ACh’s components cannot be taken up
Used to REVERSE Antagonist Block and increase ACh concentration
**Anticholinesterase
Example of AChE inhibitor
Physiostigmine
What neuromuscular blockade helps treat myasthenia gravis
AChE inhibitors like physiostigmine
**MG is Autoimmune disorder where Ig are created against nAChR Proteins
What is Novichok
AChE inhibitor that is used as a toxin and is hard to cure with antidote
Maximises lifetime of ACh and saturates the cleft, causing paralysis
**What was used against Alexie Navalny
How do non-depolarising agents work; is it additive
nACh-R competitive Antagonists
**Do not depolarise post synaptic neuron
How do depolarising agents work; is it additive
nACh-R Agonists (mimic ACh)
Persistent activation of nACh-R causes inactivation of voltage-gated Na+ channels which can no longer open in response to brief depolarisation
Block is preceded by muscle twitches
**Depolarise post-synpatic neuron
Onset and duration of Non-depolarising block and Depolarising block
Non: 3-5 mins onset; 30+ min duration
Depolarising: <1 min onset; approx 5 mins duration **Ideal for intubation
What antagonises/reverses non-depolarising blocks
Agents that Depolarise Muscle Membrane
Drugs that increase ACh Release
Anticholinesterases
Describe contraction of non-depolarising block in response to stimulation then when exposed to Anti AChE; what else also causes similar effect
(Depolarising block has similar effect to Anti AChE)
Describe contraction of Depolarising block in response to stimulation then when exposed to AChE inhibitor
3 Non-depolarising blocker examples
Atracurium
Vecuronium
Gallamine
2 Depolarising blocker examples
Suxamethonium
Dexamethonium
2 AChE inhibitor examples
Physiostigmine
Neostigmine
