Neuromuscular Blockers Flashcards
acetylcholine
major NT of the neuromuscular jxn
2 Main MOAs of Neuromuscular Blockers
- Depolarizing
- Non-depolarizing
Non-depolarizing Neuromuscular Blockers
competitive binding to ACh receptors without activating them, causes more of a flaccid paralysis
Order of Sensitivity of the Block (6)
Eye position when animal is adequately anesthetized?
ventral medial
Do NMBs have anesthetic or analgesic properties?
NO!!!!
indications for NMBs
deep surgical dissection, thoracic surgery (ventilator), dislocations, fractures, opthalmic sx
Advantages of NMBs
predictable, reversible, reduces surgical traction, easier intubation, positive pressure ventilation
Disadvantages of NMBs
needs controlled ventilation (ETT, anesthetic, ventilator), difficulty monitoring anesthesia, post-op weakness and/or hypoventilation, disease states/poher drugs
Why is it difficult to monitor anesthetic depth with NMBs?
palpebral, jaw tone, and eye position are the first muscles to be relaxed on the order of sensitivity
succinylcholine
depolarizing NMB; not used very commonly (only horses, pigs, cats)
atracurium
non-depolarizing NMB with fast onset and intermediate duration
Hofmann Elimination
spontaneous degradation affected by pH and temperature
NMB for animals with kidney or liver disease?
atracurium
Can you give atracurium to animals with mast cell tumors?
no - it can cause histamine release
rocuronium
non-depolarizing NMB with fast onset and intermediate duration
Way to monitor degree of relaxation with NMBs?
“twitch”
Train-of-Four (TOF) Stimulation
delivery of 4 stimuli at least 12 seconds apart
Antagonist of NMBs?
anticholinesterases! (like neostigmine or edrophonium)
prevents the breakdown of Ach in the NMJ
Why can’t NMB antagonists be given alone?
acetylcholine esterase will indiscriminately bind to muscarinic receptors - so we need an antimuscarinic too
2 AntiMuscarinic Drugs
glycopyrrolate
atropine
Effects of AntiMuscarinic Drugs
increase heart rate, reduce bronchial secretions, slow GI motility and reduce GI secretions
Myasthenia Gravis
autoimmune condition where antibodies target acetylcholine receptors, decreasing transmission and causing muscle weakness
Tests for Myasthenia Gravis
DNA test or Tensilon (edrophonium) test
Can NMBs be given to conscious patients?
NO
