Exam 3 - Non-depolarizing NMBD Flashcards
Selection of Non-depolarizing NMBD is influenced by what factors?
Onset
Duration of action
Rate of Recovery
Metabolism
What is the MOA of Non-depolarizing NMBD?
- Act at pre-junctional sites to block ACh release.
- Also acts on BOTH alpha subunits of the post-junctional nAChR.
- No conformational change.
Twitch characteristics with NDNMB?
- Fade w/ continuous stimulus
- Post-tetanic potentiation
- Decreased twitch response with singlw stimulus
Characteristics of NDMB?
- Potentiate other NMBD (give same drug all case)
- Antagonized by anticholinesterase drugs
- No fasiculations
Why is there a fade in twitch response with non-depolarizing NMBD?
Fade suggest some fibers are contracting while some are blocked. Some receptors are more susceptible to NMBD than others.
The cardiovascular effects of non-depolarizing NMBD are due to what factors?
Release of histamine
Effects on cardiac muscarinic receptors
Effects on nAChRs at autonomic ganglia
Most NMBDs have a ____ autonomic margin of safety.
Wide (large difference between blockade dose and CV effects dose)
Vec, Roc, Cis
What non-depolarizing NMBD has the same dose for ED95 and autonomic nervous system stimulation?
Pancuronium (sympathomimetic) will result in tachycardia at the ED95 dose
What is critical illness myopathy?
Skeletal muscle weakness occurs weeks to months after the NMBD drip is discontinued.
Factors that contribute to critical illness myopathy included:
Patients with __________ who were ventilated for six days.
__________ prior to NMBD may enhance risk.
_________ (chemical classification) blocker
Multi-System Organ Failure
Glucocorticoids
Aminosteroid Blocker
What is the altered response if a non-depolarizing NMBD and a volatile anesthetics are concurrently used?
What is the MOA?
There will be a dose-dependent enhancement to the NMBD.
(Desflurane will have the most enhancement > Sevo > Iso)
MOA: Dose-dependent inhibition nAChR
What is the altered response if a non-depolarizing NMBD was given concurrently with loop diuretics, corticosteroids, metoclopramide, and local anesthetics?
Enhance or prolong the blockade d/t depression of cholinesterase activity. Most of these drugs also decrease ACh release.
clarified by Dr. Kane
What is the altered response if a non-depolarizing NMBD is given with magnesium?
MOA?
The blockade will be enhanced.
MOA: Decreases prejunctional release of ACh and decreases sensitivity to the postjunctional membrane.
What is the altered response if a non-depolarizing NMBD is given with ephedrine (SNS drug)?
What is the altered response if esmolol is given before induction with a non-depolarizing NMBD?
Faster onset time d/t increased CO and skeletal muscle flow.
If esmolol is given before induction, there will be a delayed onset.
What altered response in non-depolarizing NMBD if there is hypothermia?
MOA?
Even with mild hypothermia, Vec and Pancuronium will double in duration.
MOA: Temperature slows down hepatic enzyme activity.
Which non-depolarizing NMBD is not metabolized by the liver but is pH and temperature dependent?
What is the MOA?
Atracurium and Cisatracurium
MOA: temperature-dependent elimination process through Hoffman elimination (need normal temperature and pH) and ester hydrolysis
Acute hypokalemia with NMBD
________ cell membrane.
Resistance to ___________
Increased sensitivity to _________
Acute hypokalemia with NMBD
Hyperpolarize cell membrane.
Resistance to depolarizing NMBD
Increased sensitivity to non-depolarizing NMBD
Hypokalemia will increase the concentration gradient of the K+, and caused more K+ to move out of the cell, decreasing resting membrane potential (making the resting membrane potential more negative). This will make the cell harder to depolarize, which is why there is resistance to depolarizing NMBD.
Acute hyperkalemia with NMBD.
There will be a partially ___________ cell membrane.
Increases effect of __________
Resistance to ___________
Acute hyperkalemia with NMBD.
There will be a partially depolarized cell membrane.
Increases effect of depolarizing NMBD
Resistance to non-depolarizing NMBD
Burns are resistant to non-depolarizing NMBD ______ days post-injury.
When does the resistance go away?
What non-depolarizing drug is the exception to burns, and what is the dose?
Ten days
Resistance goes away in 60 days.
Rocuronium 1.2mg/kg
Non-Depolarizing NMBD on stroke patients.
Paretic Arm
Unaffected Side
MOA
Paretic Arm: Resistance compared to the unaffected side
Unaffected Side: Resistance compared to normal patients
MOA: Proliferation of extrajunctional nAChRs
Which NMBD is more prone to allergic reactions?
Succinylcholine
NMBD may have cross-sensitivity to other ___________ groups.
quaternary ammonium (soaps and cosmetics)
Women are more sensitive to nondepolarizing NMBD (less muscle mass in women):
Need ____ % less vecuronium
Need ____ % less rocuronium
The duration of the block is ____ in women.
22% LESS VEC
30% LESS ROC
Greater
What is the intubating dose of Pancuronium?
Onset:
Duration until reversable:
Pancuronium
Dose: 0.1 mg/kg
Onset: 3-5 minutes
Duration until reversable: 60-90 minutes
Metabolism considerations of pancuronium?
- Renal failure: decreased plasma clearance and metabolite accumulation
- Liver failure: Larger Vd requires increased initial dose, prolonged E1/2 time
- Aging: Decreased clearance from plasma d/t decreased renal function
What are the cardiovascular effects of pancuronium?
- Increase HR, MAP, and CO from vagal blockade
- Release NE presynaptically and blocks the reuptake of NE.
- No histamine release.
Compared with long-acting NMBD.
Intermediat NMBD have a ____ onset of maximum blockade.
____ duration of action
____ CV effects
Antagonized by anticholinesterase drugs in ____ mins.
Compared with long-acting NMBD.
similar
1/3
Minimal/absent
20
Name your 4 intermediated non-depolarizing NMBD.
Vecuronium
Rocuronium
Cisatracurium
Atracurium
Vecuronium
Intubating Dose:
Onset:
Duration:
Vecuronium
Intubating Dose: 0.1 mg/kg
Onset: 3-5 minutes
Duration: 20-35 minutes
Where is Vec metabolized and excreted?
Metabolized in the liver primarily (70%), excreted in the kidneys.
Avoid in liver failure
Describe the metabolism of vecuronium in the elderly.
- Decrease Vd (less muscle mass)
- Decrease plasma clearance (less hepatic flow)
- Delayed recovery with infusion.
Describe the metabolism of vecuronium in obstetrics.
- No effect on the fetus.
- Increase clearance in 3rd trimester (progesterone)
- Prolonged duration in early postpartum (give IBW)
Acid-base changes when you give vecuronium is dependent on what?
When you gave the drug related to when the acid-base change occurred.
If there is respiratory acidosis prior to NMBD, there will be no prolonged blockade.
If there is respiratory acidosis following NMBD, there will be a prolonged blockade.
What are the cardiovascular effects of vecuronium?
None and no histamine release.
Rocuronium
Normal intubating dose:
Onset:
Duration:
Rocuronium
Normal intubating dose: 0.6 mg/kg
Onset: 3-5 minutes
Duration:20-35 minutes
Rocuronium
RSI dose:
Onset:
Duration of action:
Rocuronium
RSI dose: 1.2 mg/kg
Onset: 1-2 minutes
Duration of actions: 60-90 minutes
How is rocuronium excreted?
What conditions will result in a longer duration of action for rocuronium?
Excreted unchanged in the bile. 10-30% excreted in the kidneys.
Liver failure and elderly patients
Cardiovascular effects of rocuronium.
No histamine release.
No cardiac effects
Cisatracurium
Intubating Dose:
Onset:
Duration:
Cisatracurium
Intubating Dose: 0.1 mg/kg
Onset: 3 -5 minutes
Duration: 20 - 35 minutes
Cisatracurium is a cis-isomer of ____ .
Recovery of cisatracurium infusion is not affected by ____ .
How is cisatracurium degraded?
Atracurium
Time
Hoffman elimination (pH and temperature dependent), does not use plasma cholinesterase to degrade.
What is the metabolism of cisatracurium in the elderly and obese?
Elderly: Slight delay in onset d/t CO
Obese: Duration of action is prolonged if dosed at actual bodyweight d/t high Vd
Cardiovascular effects of Cisatracurium
No histamine effect
CV stability
Cardiovascular effect of Atracurium
Histamine release
Mivacurium
Intubating Dose
Onset:
Duration of Action
Mivacurium
Intubating Dose: 0.15 mg/kg
Onset: 2-3 minutes (patient moves, doesnt provide complete paralysis)
Duration of Action: 12-20 minutes
What stereoisomers of mivacurium have NMB ability?
Cis-trans
trans-trans
How is mivacurium broken down?
Plasma cholinesterases
Cardiovascular effects of mivacurium?
Histamine release with 3x ED 95 dose
