NMBs - Dr. Herring Review Flashcards
Which receptor does Succinylcholine bind to?
Cholinergic - Specifically Nicotinic
What are the subcategories of cholinergic receptors
Nicotinic and Muscarinic
When the nicotinic receptor is activated by ACh what enters the muscle cell and what gets dumped into the blood stream?
Na and Ca influx into myocyte (muscle cell)
Potassium efflux out of myocyte into the blood stream.
Under what conditions does more potassium than normal efflux out of the myocyte cells from ACh activation of Nm receptors?
Burn patients
Neuromuscular disorders (Duchenne MD, Multiple Sclerosis, Guillain Barre, ALS)
Spinal Trauma
Stroke
Prolonged Immobilization
What sort of things can contribute to not being able to intubate?
Not a deep enough anesthetic/paralytic
How do you recover from the use of a Depolarizing Agent (aka Succ)
Time. Release from receptor when plasma concentration declines due to change in concentration gradient.
Assuming all other things are normal, what is likely NOT the cause of Fade in your peripheral nerve stimulation?
If you have your patient Succinycholine and they have fade. Succ is likely not the cause of this
What are the normal Dibucaine Numbers?
70-80. This means dibucaine has inhibited 70-80% of the pseudocholinesterase in the sample.
What does the ED95 of a drug tell you, what does it help you predict?
The dose at which there is a 95% decrease in twitch height.
If given an ED95 of a few drugs. What predictions can you make about them?
The lower the ED95, the MORE POTENT but SLOWER the onset.
The higher ED50 is LESS POTENT W/ a FASTER ONSET
What is the ED95 of Rocuronium
What is the ED95 of Atracurium
0.3mg/kg
.15mg/kg
What is the ED95 of Succynlcholine
0.3mg/kg
Drug X, ED95 = 0.6mg/kg
Drug Y, ED95 = 0.2mg/kg
Which drug is more potent? Which will have a faster onset?
Drug Y is more potent. Lower ED95, takes less drug to have same effect.
Drug X has a faster onset. Higher concentration of drug being delivered.
You’re using a non-depolarizing NMB in hepatobiliary surgery. Which drug might you choose to use?
Cisatracurium - not metabolized/eliminated by liver or bile. It’s by Hoffman Elimination.
What NMB could lower your seizure threshold if you had to repeat dose?
Atracurium. Active metabolite.
Metabolite laudanosine
i. Crosses BBB
What is the classification of Atrurium, Cisatracurium, Mivacurium?
Non-depolarizing Benzylisoquinolione
Between the two classes of Non-Depolarizing NMBs - what are the side effect profiles of them? What are these side effects mostly from? Which drug in the class is an exception?
Benzylisoquinolione vs AminoSteroid
Benzyl is more likely to cause Histamine release causing hypotension, tachycardia, and flushing.
Cisatracurium - does not cause a histamine release
For Preeclampsia and Eclampsia - what are the mainstay bedside treatments for this patient population? How does this treatment affect our anesthetic NMBs?
Magnesium
It can potentiate and prolong NMBs in both depolarizing and nondepolarizing.
(extra: Inhibits calcium influx at presynaptic nerve terminal, reducing release of Ach into synaptic cleft. Reducing binding of Ach.
ii. Decreases excitability at postsynaptic nicotinic receptors
iii. Potentiates and prolongs duration and delays recovery
iv. Mag reduces Ach release, making depolarization weaker
v. Effects both depolarizing and non-depolarizing NMBs)
Are there any antibiotics that can influence our neuromuscular relaxation
Aminoglycosides
-Gentamicin, Tobramycin
Clindamycin
Why do we place peripheral nerve stimulator electrodes where we do?
place them upstream of the muscle, directly on muscle could stimulate the nerve without ACh.
What would be our neuromuscular blocking plan for a patient getting a parathyroidectomy?
Succ! you want fast on and fast off.
Which combination of subjective tests would give you the most confidence in your NMB recovery and clear to extubate
is a Train of Four a subjective or objective NMB assessment
subjective
What is the maximum train of 4 ratio you can have with 3 out of 4 twitches?
0.8
A 100% blockade of the nicotinic receptor at the neuromuscular end plate corresponds to what findings on your peripheral nerve stimulator?
No response on your TOF
What objective measure would tell you you are ready to extubate in reference to your neuromuscular blockade
TOF Ration greater than or equal to 0.9
Between facial nerve and ulnar nerve stimulation with TOF, which is more representative of diaphragm recovery?
Ulnar
What is the MOA of Neostigmine and Sugammadex? Know the difference between the 2.
Neostigmine inhibits AChE, which increases the ACh concentration in the synaptic cleft. This overpowers the non-depolarizing NMB and facilitates the removal of NMB from the receptor. The increased ACh activates muscarinic receptors. Causing bradycardia, bronchospasm, excessive secretions, and diarrhea.
Sugammadex - hugs and encapsulates nondepolarizing NMBs and carries them away to the kidneys.
If I gave a reversal and my patient suddenly became tachycardia, why is that?
This is likely due to using an anticholinergic such as atropine or glycopyrolate. These are antivagalytics.
What information do you need to dose your Sugammadex?
Twitch count and TOTAL body weight.
2/4 Twitches or better = 2mg/kg
0/4 twitches + 2 or more Post tetanic twitches = 4mg/kg
If reversing a full induction dose = 16mg/kg
If you give Sugammadex to reverse your paralytic, what population should receive additional instructions?
Women of childbearing age
Hypersensitivities
If your patient required and had a profound NMB, what are some of the risks of Neostigmine?
Administration to patients who present with deep NMB can result in incomplete reversal. The patient could experience paralyzation.
You have a patient with severe liver and renal dysfxn. Which NMB might you choose?
Cisatracurium
If you were using Rocuronium for standard intubation, what might you do before pushing the paralytic?
Sedate First
Eyelash Reflex
Ensure Ventilation
Inappropriate sustained release of calcium from the sarcoplasmic reticulum results in?
Malignant Hyperthermia
What is occurring in malignant hyperthermia from a molecular level?
Which NMB agent is a MH trigger?
Succinylcholine
