24 Mar 25 Nondepolarizing NMBDs without reversals Flashcards
What is the primary use of succinylcholine?
Rapid airway protection
What are non-depolarizers chosen based on?
Comorbidities like liver and renal failure, surgery duration
What must be present to use anticholinesterase reversal agents?
At least one twitch
What is a potential issue with mixing non-depolarizers?
They can potentiate each other
What is the consequence of mixing different non-depolarizers?
Cumulative effects leading to prolonged paralysis
What is critical illness myopathy?
Skeletal muscle weakness persisting after neuromuscular blocker discontinuation
What factors contribute to critical illness myopathy?
Prolonged ventilation, high-dose glucocorticoids
What is the significance of the train of four ratio in neuromuscular blockade?
A ratio less than 0.7 indicates a phase two block
What cardiovascular effects can non-depolarizers have?
Histamine release, cardiac muscle receptor effects
What is the importance of patient body temperature in drug metabolism?
Maintaining normal body temperature optimizes drug metabolism
Fill in the blank: Pancuronium is a _______ non-depolarizer.
Long-acting
What impact does gender have on neuromuscular blockers?
Women may require less due to less muscle mass
What is the primary concern when using rocuronium in patients with liver failure?
Its hepatic metabolism may lead to prolonged effects
What are the characteristics of intermediate-acting non-depolarizers?
Onset, duration, and metabolism vary among agents like vecuronium and rocuronium
True or False: Allergic reactions to non-depolarizers are common.
False
What is the role of sugammadex in neuromuscular blockade?
Reversal of neuromuscular blockade
What is mivacurium known for?
Short duration and historical use in brief procedures
How does hypothermia affect neuromuscular blockers?
It alters enzymatic activity
What is the significance of the autonomic margin of safety?
It relates to the therapeutic index of neuromuscular blockers
What should be monitored during long surgeries with neuromuscular blockers?
Cumulative effects and patient comorbidities
What is the main concern with using high doses of rocuronium?
Achieving rapid onset similar to succinylcholine
Fill in the blank: The phase two block is characterized by a _______ twitch response.
Decreased
What are the implications of using non-depolarizers in patients with comorbidities?
Altered metabolism and clearance
What is the significance of monitoring for adverse effects when using neuromuscular blockers?
To prevent complications and ensure patient safety
What is endless myopathy?
A skeletal muscle weakness that persists for weeks to months after decreasing or stopping neuromuscular blocking drugs.
Most literature indicates this occurs in patients ventilated for over six days.
What is the relationship between glucocorticoids and spinal cord injuries?
High doses of glucocorticoids given within the first 24 hours may improve recovery chances.
Not all literature agrees on this point.
What factors may influence how patients react to neuromuscular blocking drugs?
Unknown hepatic or renal issues, co-morbidities, and the use of drugs with prolonged effects.
Patients may come intubated and unconscious, complicating history-taking.
How do volatiles affect neuromuscular blocking?
They enhance neuromuscular relaxation in a dose-dependent manner.
The exact mechanism with acetylcholine receptors is not fully understood.
Which drugs can enhance or antagonize neuromuscular blockade?
Drugs that can enhance or antagonize neuromuscular blockade include:
* Diuretics
* Corticosteroids
* Local anesthetics
* Magnesium
What effect does hypothermia have on enzymatic activity?
Hypothermia slows down all enzymatic activity in the body.
Keeping patients warm is critical, especially for the elderly or debilitated.
What is the difference between atracurium and cisatracurium?
Atracurium releases histamine while cisatracurium does not and is considered the ‘good isomer’.
Both are metabolized by temperature-dependent processes.
What can cause acute hypo and hyperkalemia when using neuromuscular blockers?
Changes in serum potassium levels can occur due to:
* Neuromuscular blockers
* Burns
* Muscle trauma
What is a potential strategy for intubating burn patients resistant to neuromuscular blockers?
Administer double the dose of rocuronium to achieve the onset time of succinylcholine without its negative side effects.
This is effective if the patient will be intubated for hours or days.
What phenomenon may occur in the arms of a stroke patient regarding neuromuscular blockers?
The paralyzed arm is more resistant to neuromuscular blockers compared to the non-paralyzed arm, which may also show some resistance.
This highlights the importance of preoperative assessment.
Are allergic reactions common with neuromuscular blocking drugs?
Allergic reactions to neuromuscular blocking drugs are unlikely, with more common reactions being histamine-related.
Cross-sensitivity may occur with substances containing a quaternary ammonium group.
Why might women require less neuromuscular blocking drugs compared to men?
Women are generally more sensitive to neuromuscular blocking drugs and require lower doses.
The reasons for this sensitivity are not fully understood.
What is the main reason women are more sensitive to neuromuscular blocking drugs?
Women tend to have less muscle mass than men
This results in a longer duration of action for the same dosage.
What is the duration of action for pancuronium?
60 to 90 minutes
Pancuronium is a long-acting neuromuscular blocker.
What is the onset time for pancuronium?
3 to 5 minutes
This is the time required before intubation can occur after administration.
What significant side effect is associated with pancuronium?
Tachycardia
It is a vagolytic drug that can increase heart rate.
What percentage of pancuronium is eliminated in the urine?
80%
Caution is advised in patients with renal failure.
What are the concerns related to using pancuronium in elderly patients?
Increased renal insufficiency and decreased muscle mass
These factors can prolong neuromuscular blocking effects.
What is the duration of action for vecuronium?
20 to 35 minutes
This is the time until it can be reversed, not the complete clearance from the system.
What is the primary route of metabolism for vecuronium?
Liver
Caution is necessary for patients with liver disease.
Which neuromuscular blocking drug is known to release histamine?
Atracurium
It is not commonly used in the OR due to this side effect.
What is the dose of rocuronium for normal and high doses?
Normal: 0.6 mg/kg; High: 1.2 mg/kg
The high dose increases the duration of action.
What is the onset time for rocuronium?
3 to 5 minutes
Similar to vecuronium.
What is the primary route of excretion for rocuronium?
Bile
It is also partially excreted by the kidneys.
True or False: Intermediate acting neuromuscular blockers have significant cardiovascular effects.
False
They do not have significant cardiovascular effects unless they release histamine.
Fill in the blank: Neuromuscular blocking drugs can have prolonged effects in patients who become _______.
acidotic
Acidosis decreases the amount of drug bound, increasing availability at receptors.
What factor can complicate the use of neuromuscular blockers in elderly patients?
Decreased volume of distribution
This is due to less muscle mass and decreased plasma clearance.
How does the pharmacokinetics of neuromuscular blockers differ in elderly patients?
Decreased clearance and increased duration of action
This is due to physiological changes associated with aging.
What is a significant consideration when administering neuromuscular blockers during surgery?
Monitoring ventilation and acid-base balance
Failure to do so can prolong neuromuscular blockade effects.
What is the primary method of excretion for rock and uranium?
Excreted unchanged in the bile
Concerns arise in liver failure patients due to this excretion method.
What are the concerns with muscle relaxants in liver failure patients?
Red flag for liver failure, liver enzymes elevation, yellow skin
Procedures like ERCPs can also be a concern.
What is the renal impact of rock?
Minimal impact; not much excreted by kidneys
No significant cardiac effects due to lack of histamine release.
What type of drug is cisatracurium?
Intermediate acting benzolace quinolone
It is commonly used in intubation.
What is the onset time for cisatracurium?
3 to 5 minutes
Duration is 20 to 35 minutes.
How does cisatracurium degrade?
By Hofmann elimination
This process is temperature dependent.
What is the cardiovascular stability of cisatracurium?
Very stable cardiovascularly
This contributes to its safety profile.
What is the common duration of action for mivacurium?
Short acting
It is not currently on the market in the United States.
What is a significant drawback of mivacurium?
Does not provide solid paralysis
It was often insufficient for extended intubation needs.
What is the onset time for mivacurium?
2 to 3 minutes
This rapid onset is useful for short procedures.
What is the neuromuscular blocking activity of mivacurium attributed to?
Trans isomer
This isomer is responsible for the drug’s effectiveness.
How is mivacurium cleared from the body?
By plasma cholinesterase
It is not dependent on liver or kidney function.
What is a common use case for mivacurium?
Short procedures like pin drilling or breaking scar tissue
It is effective for brief intubation needs.
What is the histamine release effect of atracurium?
Releases a lot of histamine
This can cause cardiovascular concerns.
What should be considered when administering propofol to older patients?
Delayed response due to slower cardiac output
Older patients may take longer to respond after administration.
What are the cardiovascular effects associated with NMBDs?
Minimal effects, histamine release, transient MAP drop with > 3 x ED95
More common with rapid, large doses; MAP drop more in hypertensive patients than non-hypertensive patients.
What are the three stereoisomers of NMBDs?
- Cis-cis
- Cis-trans
- Trans-trans
How is Rocuronium cleared from the body?
Cleared by plasma cholinesterase
Not currently on the market.
What is the intubating dose of Rocuronium?
0.6 mg/kg or 1.2 mg/kg
What is the onset time for Rocuronium?
3-5 minutes; 1-2 minutes for larger doses
What is the duration of action for Rocuronium?
20-35 minutes; 60-90 minutes for larger doses
What are the cardiovascular effects of Rocuronium?
Essentially none; no histamine release
What happens to acid-base status before NMBD administration?
No prolonged blockade
What effect does respiratory acidosis have following NMBD administration?
Prolongs blockade
How does acidosis affect drug binding?
Activity inversely proportional to bound drug; acidosis decreases bound amount
What are the metabolic changes in elderly patients regarding NMBDs?
- Decreased volume of distribution
- Decreased plasma clearance
What is the effect of NMBDs on the fetus during pregnancy?
Insignificant effects
What is the primary organ responsible for the elimination of NMBDs?
Liver
What is the metabolite of Vecuronium and its potency?
3-desacetylvecuronium is 50-80% as potent but rapidly converted to a metabolite with 1/10 the effects
What percentage of Vecuronium is excreted unchanged in bile?
10-30%
What is the intubating dose for Vecuronium?
0.1 mg/kg
What is the onset time for Vecuronium?
3-5 minutes
What is the duration of action for Vecuronium?
20-35 minutes
What are the cardiovascular effects of Vecuronium?
No histamine release, no cardiac effects
What are the characteristics of neuromuscular blockade?
- Decreased twitch response to a single stimulus
- Unsustained response (fade) to continuous stimulus
- TOF ratio < 0.7
What is the mechanism of action (MOA) for non-depolarizing NMBDs?
Act at pre-junctional sites to block Ach release
What is the metabolism process for Cisatracurium?
Recovery from infusion is not affected by time; degradation via Hoffman elimination
What is the intubating dose for Cisatracurium?
0.1 mg/kg
What is the duration of action for Cisatracurium?
20-35 minutes
What are the cardiovascular effects of Cisatracurium?
No histamine release; cardiovascular stability
What are the effects of magnesium on NMBDs?
Enhances blockade
What is the effect of hypothermia on NMBDs?
Even mild hypothermia can double the duration of Vecuronium and Pancuronium
What is the intubating dose for Pancuronium?
0.1 mg/kg
What are the characteristics of Pancuronium?
Bisquaternary aminosteroid with vagolytic properties
What percentage less do women need of Vecuronium compared to men?
22%
What percentage less do women need of Rocuronium compared to men?
30%
What is the only clinically useful short-acting non-depolarizer?
Mivacurium
What is the duration of action for Mivacurium?
12-20 minutes
