37 Questions
What is one result of repetitive stimulation in the presence of non-depolarizing block monitoring?
Fade
How do volatile anesthetics affect neuromuscular blockers?
Potentiation
Why is clinical assessment of recovery from neuromuscular blockade considered unreliable?
Subjective nature
What is recommended to prevent residual paralysis and associated complications when using a nerve stimulator?
Objective measurement
Why is monitoring at particular sites for neuromuscular block onset and recovery considered unreliable?
Underestimates onset and recovery
How do anticholinesterases work in the context of non-depolarizing neuromuscular blockers?
Increase ACh levels at NMJ
What is the purpose of pairing anticholinesterases with an antimuscarinic for neuromuscular blockade reversal?
Prevent muscarinic effects
What is the key reason for pairing anticholinesterases with antimuscarinic drugs during neuromuscular blockade reversal?
Prevent unwanted muscarinic effects
What is the primary mechanism of action for succinylcholine and non-depolarizing neuromuscular blockers?
Binding the alpha subunits of NAChRs
Which type of neuromuscular blocker is most likely to exhibit a fade on train-of-four monitoring during typical block monitoring?
Non-depolarizing neuromuscular blockers
What is one of the significant side effects associated with succinylcholine but not with non-depolarizing neuromuscular blockers?
Malignant hyperthermia trigger
How do non-depolarizing neuromuscular blockers result in neuromuscular block?
By competitive antagonism of Ach binding
Which type of neuromuscular blocker is contraindicated for routine use in otherwise healthy children?
Succinylcholine
What may result from an increase in the 'immature' forms of NAChRs following administration of a depolarizing NMB?
Excessive potassium release
What is the primary effect of sugammadex on aminosteroidal neuromuscular blockers like rocuronium and vecuronium?
Encapsulates and renders them ineffective
Which of the following is a potential consequence of inadequate reversal of muscle relaxant at the end of surgery?
Risk for hyperkalemic arrest following succinylcholine use
What type of receptors are predominantly expressed in mature, innervated muscle at the end-plate region?
ε receptors
In which circumstance would there be an increase in immature acetylcholine receptors in response to decreased stimulation of the neuromuscular junction?
During recovery from severe infection or sepsis
Which disease state may lead to hyperkalemia following the use of succinylcholine due to upregulation of immature α7 nicotinic Ach receptors?
Critical illness polyneuropathy
What is a characteristic of succinylcholine Phase II block that distinguishes it from Phase I block?
Presence of fade on train-of-four monitoring
How does succinylcholine primarily act on the neuromuscular junction to induce muscle paralysis?
Induction of prolonged depolarization through sodium influx
Which of the following statements about sugammadex is most accurate?
Sugammadex is excreted primarily by the kidneys.
What is the recommended waiting period before re-administering rocuronium after reversal with sugammadex?
24 hours
How does sugammadex reverse neuromuscular blockade at the neuromuscular junction (NMJ)?
By promoting the movement of NMB back into the plasma.
What is the dosing recommendation for sugammadex when reversing profound neuromuscular blockade?
16 mg/kg
Which factor may lead to prolonged recovery of neuromuscular function with sugammadex?
Presence of renal disease
Regarding side effects, which statement accurately reflects the information provided about sugammadex?
Interference with oral contraception may occur with sugammadex.
What role does sugammadex have in reducing postoperative nausea and vomiting (PONV) compared to anticholinesterases?
Reduced PONV relative to anticholinesterases
What is one significant consideration regarding the expense of sugammadex?
$90 per vial
What is defined as partial paralysis in the context of the provided text?
Train-of-four (TOF) ratio of 0.70
Which patient group is more likely to experience partial paralysis according to the text?
Asthmatic patients receiving high-dose steroids
What conditions are associated with prolonged use of neuromuscular blockers according to the text?
Critical Illness Myopathy (CIM) and Critical Illness Polyneuropathy (CIP)
When is neuromuscular monitoring recommended in the ICU according to the text?
When neuromuscular blockade is necessary
In which situations are adequate intubating conditions not always attainable without neuromuscular blocker usage?
During dental procedures
What medical condition is associated with more common occurrence of partial paralysis as per the text?
Renal failure
What effect does high-dose steroid administration have on partial paralysis according to the text?
Increases likelihood
What should be allowed to monitor periodic return of muscle function when neuromuscular blockade is necessary in the ICU, according to the text?
Periodic return of muscle function
Study Notes
Neuromuscular Blockers
- Neostigmine: dose 20-70 μg/kg (supplied as 1.0 mg/ml), paired with glycopyrrolate (20-25% of neostigmine dose)
- Edrophonium: dose 0.5-1.0 mg/kg (supplied as 10 mg/ml), paired with atropine
- Sugammadex: a selective relaxant binding agent (SRBA), reverses effects of rocuronium and vecuronium, highly water soluble, minimal metabolism, excreted by kidneys, T1/2 ~100 minutes
Sugammadex
-
Dosing and Onset:
- Moderate block (TOFC > 2): 2 mg/kg, reversal to TOF >0.9 in 2-4 minutes
- Deep block (PTC >1, TOF = 0): 4 mg/kg, mean reversal time = 2.9 minutes
- Profound block (PTC = 0, TOF = 0): 16 mg/kg, reversal time = 2-4 minutes
-
Side Effects:
- Hemodynamic: none
- Hypersensitivity reactions (anaphylaxis): 1:3500 – 1:20,000
- Coagulation: minimal, brief increase in PT and PTT lasting < 60 minutes
- Hypothermia: mild, increases reversal time by < 1 minute
- Interference with oral contraception: equivalent to missing one dose, alternative means of birth control suggested for one week
Reversal of Neuromuscular Blockade
- Anticholinesterases: paired with an antimuscarinic to prevent muscarinic effects, increases ACh levels at the NMJ to compete with NMB drug
- Sugammadex: alternative to anticholinesterases, binds to and encapsulates steroidal NMBs, reducing free NMB concentration in plasma, concentration gradient favors NMB movement from NMJ to plasma, reversing blockade
Neuromuscular Blockade
- Fade on Train-of-Four (TOF) monitoring: characteristic of non-depolarizing NMBs, not seen with succinylcholine
- Post-tetanic Facilitation: characteristic of non-depolarizing NMBs, not seen with succinylcholine
- Residual Neuromuscular Blockade: more common in asthmatic patients receiving high-dose steroids, renal failure, and with steroidal NMBs
Monitoring Neuromuscular Blockade
- Clinical Assessment: unreliable, predisposes to residual postoperative neuromuscular blockade and increased morbidity
- Nerve Stimulator: results in marked increase in likelihood of residual paralysis and complications when used without objective measurement
- Monitoring Sites: different muscles have varying sensitivity to and recovery from NMBs, monitoring at specific sites may under- or overestimate onset and recovery
Explore key points related to changes in nicotinic acetylcholine receptors (NAChRs) and their impact on responses to depolarizing and non-depolarizing neuromuscular blockers. Learn about the effects of immature NAChRs on potassium release, as well as how succinylcholine and non-depolarizing NMBs interact with NAChR alpha subunits.
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