Module 4a: Overview of neuromuscular blockers Flashcards
What is the key neurotransmitter at the neuromuscular junction?
ACH, stored in pre-synaptic vesicles
To what receptors does ach bind to on post-junctional membrane?
nicotinic cholinergic receptors
What enzyme breaks down ach
AChE (acetylcholinesterase)
What 3 things can be blocked to achieve muscle relaxation
motor nerves(local anaesthetics)
The NMJ (IV muscle relaxants)
Receptors inside muscle cells (dantrolene)
What are the 2 types of neuromuscular blockers?
Depolarizing agents: SUXAMETHONIUM
Non-depolarizing agents: All other muscle relaxants
What is the mechanism of action of Depolarizing agents
non-competitive action
CANNOT be reversed-> wear off/are metabolised over time
What is the mechanism of action of non-depolarisers
Competitive inhibition
Competes with Ach for nicotinic receptors
REQUIRES reversal
What is ED95?
Effective dose of muscle relaxant that will paralyse 95% of normal people
How can you use ED95 to estimated intubating dose?
Intubating dose: ED95 x 2
What are the 3 characteristics of adequate paralysis?
Inability to breathe
Inability to maintain airway
Loss of protective reflexes
True or false: With adequate paralysis, the patients’ consciousness is completely impaired?
False, the consciousness is completely UNIMPAIRED
Name 5 factors that potentiate muscle relaxants?
Drugs
Electrolytes
pH
Temperature
Diseases
Which drugs potentiate muscle relaxants
Inhalational agents(because they are calcium channel blockers)
Aminoglycoside antibiotics like gentamycin
What electrolyte disturbances potentiate muscle relaxants
hypocalcaemia, hypokalaemia and high magnesium
What pH state potentiates muscle relaxants?
Acidosis
