Lecture 2 Neuromuscular/Ganglionic Blockers Flashcards
Ganglionic blockers are ______ receptor _____
nicotinic, antagonists
2 important ganglionic blockers to know:
Why are these not commonly used?
trimethaphan, mecamylamine
they block the entire ANS (ie block pupillary reflex and baro-receptor reflex)
Uses of trimethaphan:
Use of mecamylamine:
trimeth = hypotension for surgery
mecamylamine = tourette’s, smoking cessation, severe hypertension
In general, the ____ tone is stronger than the ____ tone. What is the exception to this and why does this exception occur?
parasympathetic, sympathetic;
smooth muscles of vascular tone (ie regular vasoconstriction), because the M3 receptors are not innervated
ganglionic blockade results in ____ and ____
vasodilation, tachycardia
Therapeutic use for neuromuscular blockers?
surgery and intubation
What was the first clinically used neuromuscular blocker, and what was the active component of it?
curare
d-tubocurarine
Without blockade, how many twitches of the thumb should be seen with the “Train of 4 test”? The train of 4 ratio is the ratio of the ____ twitch to the ____ twitch
4; 4th, 1st
Sedation is said to be complete with a TOF ratio of ___, or ____ twitches out of 4 impulses.
.25; 1-2
Recovery to a TOF ratio of ___ is needed before extubation. A ratio of ___ is for “full clinical recovery”
.7;
.9
(Depolarization/Non-depolarizing) blockers will show a decrease in response strength between subsequent stimuli, called fade.
This is absent in (non-depolarizing or depolarizing?) blockers until a TOF ratio of 0.3 is reached. This is called phase ____
depolarizing,
non-depolarizing
II
No additional dose of blocker should be given if __ twitches are observed with the TO4 test
no
Sequence of muscle paralysis by curare/neuromuscular blockers:
eye/speech–>extremities/limbs –> intercostals –> diaphragm
ie outside in. mimics GBS
_____ is a depolarizing NAchR agonist. It is ____ acting as it is rapidly metabolized by _____
Succinylcholine (Sux);
short, butyrylcholinesterase
Sux should be avoided in patients with _____ as additional release of ____ can cause cardiac arrest
hyperkalemia,
potassium
Specifically, Sux inhibits ____ of the NAchR receptor, preventing further action potentials from occuring. ___ use of the agonist will give a muscle twitch
repolarization;
first
Pancuronium./vecuronium/atracurium are _____ neuromuscular blockers that are ______ of Nicotinic receptors
non-depolarizing;
competitive antagonists
Non-depolarizing neuromuscular blockers are easily ____ and have a ____ duration of action.
reversable; long
What is a short acting non-depolarizing neuromuscular blocker?
trimethaphan
reverseal of non-depolarizing blockade:
- use of an AchE inhibitor such as _____. It increases levels of Ach to compete with the antagonist.
- Use of ____ which binds and sequesters pancuronium
neostigmine,
sugammedex
AchE inhibitors rely on the presence of Ach. ie, they have little effect on the function of ____ receptors located in ____ ____
M3; blood vessels
AchE is located in ____. BuChE is located in ____ and prefers _____ and other local anaesthetics such as procaine.
synapses;
plasma, succinylcholine
Three classes of AchE inhibitors:
carbamates, organophosphates, quarternary ammonium alcohols
Carbamates can be tertiary or quarternary amine groups. they temporarily create a ____ ____ with AcheE, but it is rapid and reversible
covalent bond
