NMBDs: Physiology/Succinylcholine (Exam III, Andy's Cards) Flashcards
Which of the following is the newest NMBD?
A. Atracurium
B. Vecuronium
C. Pancuronium
D. Cistracurium
A. Atracurium (1980)
B. Vecuronium (1980)
C. Pancuronium (1960)
D. Cistracurium (1995)
Why was Rapacurium (Raplon) discontinued in 2001?
Massive laryngospasm and bronchospasm leading to death.
The effect of NMBD is to interrupt the transmission of nerve impulses at the _____.
Neuromuscular Junction (NMJ)
The MOA of NMBD is either depolarizing or non-depolarizing.
Deploarizing NMBD will _________ the action of ACh.
Non-depolarizing NMBD will ______ the action of ACh.
Deploarizing NMBD will mimic the action of ACh.
Non-depolarizing NMBD will interfere with the action of ACh.
Purpose of NMBD for anesthesia.
- Decrease airway trauma
- Facilitate surgical exposure
- Minimize injury from patient movement
What classification of NMBD is Succinylcholine (Anectine)?
Depolarizing NMBD
Only depolarizing agent used in anesthesia.
Name a long-acting non-depolarizing NMBD.
Pancuronium (Pavulon)
Name a short-acting non-depolarizing NMBD.
Mivacurium (Mivacron)
Move a lot, short-acting
What is the chemical classification of Pancuronium?
Aminosteroid
What is the chemical classification of Mivacurium?
Benzylisoquinoline
What is the chemical classification of Pancuronium (Pavulon)?
Aminosteroid
Which intermediate-acting NMBDs are Benzylisoquinolines?
Atracurium (Tracrium)
Cisatracurium (Nimbex)
Which intermediate-acting NMBD are Aminosteroids?
Vecuronium (Nocuron)
Rocuronium (Zemuron)
What is ED95 in regards to NMBDs?
The potency of NMBD. The dose that is necessary to produce a 95% suppression of a single twitch in the presence of nitrous/ barbiturate/ opioid anesthesia.
What nerve is stimulated so that the adductor pollicis muscle will produce a single twitch at 1 Hz (thumb adduction)?
Ulnar nerve
The order of block for NMBD is dependent on:
- Number of presynaptic ACh-containing vesicles released.
- Number of ACh receptors.
- Blood Flow to the area.
- Drug potency
Low potency NMBD will onset _________ than higher potency NMBD.
Faster
Lower potency NMBD will have more molecules than higher potency NMBD. This will create a higher concentration gradient and result in a faster onset.
Small, rapidly moving muscles will be blocked ________ than large muscles.
Faster
Eyes will be paralyzed first before diaphragm.
What does this graph show?
- Both Larynx and Adductor Pollicis muscle received 0.5 mg/kg of Rocuronium.
- Both muscles experience a dramatic decrease in twitch percent height, but the adductor pollicis is completley blocked while the larynx got down to a twitch height of 20%.
- Both muscles recovered at the same rate. Almost 100% twitch response returned by minute 40.
Checking a twitch in which muscle will assess the diaphragm and laryngeal muscle blockade.
Orbicularis Oculi
If there are no twitches to the facial nerve, the diaphragm and laryngeal muscles are adequately blocked. Best indicator of intubating conditions.
The orbicularis oculi underestimates _____________.
residual paralysis.
Is checking a twitch in the adductor pollicis a good indicator for laryngeal relaxation?
No, it is not a good indicator of laryngeal relaxation.
Checking a twitch of the adductor pollicis is a good indicator or peripheral recovery.
Which muscle is the gold standard to check a twitch on for recovery?
Adductor pollicis (Ulnar Nerve)
What is the placement of electrodes on ulnar nerve?
What will the response be?
What is a defasciculating dose of NMBD?
What symptoms will the patient experience with a defasciculating dose?
Where 20% of intubating dose is given early (primer) to prevent fasciculation.
Blurred Vision
Mandibular weakness
Ptosis (droopy eyes)
Diplopia (double vision)
Dysphagia
Increased hearing acuity - people need to be quiet
Let patient know they might start to feel week and get blurry vision. Encourage them to close their eyes.
A single twitch nerve stimulator starts at _____ Hz/second decreasing to ______ Hz/10 secs.
1 Hz/sec to 0.1 Hz/10 secs
With an onset of a block a single twitch will ______.
fade with each stimulus
Double burst stimulator is _____ short bursts followed by ______ short bursts.
The double burst stimulator setting uses ________ Hz
3, 3
50 Hz (supramaximal current)
Why was the double burst stimulator developed?
Developed to improve detection of residual block (fade).
Fade in 2nd response vs 1st response.
Qualitatively better than TOF.
Train of Four is ________ stimuli at _______ Hz with ______ seconds between each burst.
4 stimuli at 2 Hz with ½ seconds between each burst
TOF reflects events at _________ membrane.
Presynaptic
Prior to NMBD what will be your twitches on the TOF?
What will be the TOF ratio (Twitch 4 : Twitch 1)?
4/4 twitches
Ratio 1
Experienced anesthetist are unable to qualitatively detect the fade of a TOF < ______.
0.4
The twitch will have to go from unblocked to completely blocked in order to tell a difference
There will be significant residual block with a TOF of ______ to _____.
0.7 to 0.9
You will not feel a fade, but there will still be blockade at the NMJ. Patient will still need reversal agent.
Tetanic stimulation is very rapid, it will be ________ Hz for _____ seconds.
50 Hz for 5 seconds
If a _____ NMBD is given, a tetanic stimulation will result in a sustained muscle response.
Depolarizing NMBD (Succinylcholine)
If a _____ NMBD is given, a tetanic stimulation will result in a non-sustained muscle response (fade).
Nondepolarizing NMBD (Roc/Vec)
The fade is a result of presynaptic depletion of ACh or inhibition of release
What is post-tetanic stimulation?
Single twitch 3 seconds after tetanic stimulation.
The post-tetanic stimulation will occur d/t accumulation of calcium during tetany, the excess calcium will stimulate ACh release.