Exam 4 - NMB Reversals Flashcards
What is another name for neuromuscular monitoring?
Acceleromyography
What does it mean for NMB reversal drugs to have a ceiling effect?
How does this effect reversal?
“Once the inhibition of acetylcholinesterase is complete, administering additional doses of neostigmine will serve no useful purpose because the concentration of acetylcholine that can be produced at the neuromuscular junction is finite.” - Stoelting p. 1052
This means that NMB drugs will not be able to reverse deep blockade (no twitches)
Max dose for neostigmine and edrophonium?
Neostigmine: 50 mcg/kg or 5 mg
Edrophonium: 1 mg/kg
Reversal of NMJ blockade is dependent on these 5 factors:
- Depth of block
- Drug choice (neo vs edro)
- Dose
- Rate of plasma clearance
- Anesthetic agent and depth
What is the onset and duration of neostigmine?
Onset: 5 - 10 min
Duration: 60 min
What is the dosage of edrophonium?
1 mg/kg
What is the onset and duration of edrophonium?
Onset: 1-2 min
Duration: 5-15 min
What is the formula for glycopyrrolate to be used with a NMB reversal drug?
0.2 mg of glycopyrrolate / mg of neostigmine
What is the max dose for glycopyrrolate?
1 mg
A 100 kg patient has 2/4 twitches. Neostigmine is available in 1 mg/mL vials. How much neostigmine will you give in mL?
5 mL (max dose of 5 mg)
What percentage of neostigmine is renally excreted?
50%
What percentage of both pyridostigmine and edrophonium are renally excreted?
75%
How are NMB reversal agents cleared if the patient has no innate renal function?
30 - 50% cleared hepatically
What is the major side effect of NMBD reversal agents?
↑PSNS activity (from increased nACh and mACh activity)
What drugs would be coupled with NMBD reversal agents to prevent adverse side effects from these drugs?
Anti-cholinergic / Anti-muscarinics
- Atropine for edrophonium
- Glycopyrrolate for neostigmine and pyridostigmine
If you’re concerned about someone’s cardiac status due to existing disease, which Anticholinergic drug would you use?
Glycopyrrolate
What is the dose of atropine for use with edrophonium?
10 mcg/kg
What common side effects are seen right after atropine administration?
- Mydriasis
- Tachycardia
How long does glycopyrrolate need to be administered over?
2 - 5 min
Mechanism of persistant NM blockade?
Treatment?
- Maximum AChesterase inhibition
- Sedation and post op ventilation
What patient conditions may effect NMBD reversal?
- Metabolic acidosis
- Respiratory acidosis
- Hypothermia
What reversal drug is specific to mivacurium?
Purified human plasma cholinesterase
What reversal drug is specific to gantacurium?
Cystiene
What reversal drug is very specific to aminosteroids?
Sugammadex
What type of drug is sugammadex?
Selective relaxant-binding agent
What should be known about sugammadex’s organic structure and physical properties?
- γ-cyclodextrin
- Dextrose units from starch
- Very H₂O-soluble
What is the MOA of Sugammadex?
Encapsulates rocuronium via:
- Van der Waals forces
- H-bonds
- Hydrophobic interactions
What drugs does sugammadex work with best?
Roc > Vec > Pancuronium
Where does suggamadex work?
It binds to NMB drug in the plasma
What is the E ½ time of sugammadex?
2 hours
How is sugammedex eliminated?
Urine:
- 70% gone in 6 hours
- 90% gone in 24 hours
When is sugammadex contraindicated?
Renal impairment on dialysis
Differentiate a moderate block vs a deep block.
- Moderate: 2/4 twitches on TOF
- Deep: No twitches to TOF, but will have a twitch w/ post tetanic stimulation
What is the Sugammadex dose for a moderate block?
2 mg/kg
What is the Sugammadex dose for a deep block?
4 mg/kg
What is the sugammadex dose for an extreme (overdose) block?
8 - 16 mg/kg
What are the side effects of Sugammadex?
- dose-related N/V
- dose-related Pruritis
- dose-related Urticaria
- Anaphylaxis
- Bradycardia
If 1.2 mg/kg of rocuronium needs to be re-administered after reversal with sugammedex. What is the minimum waiting time?
5 min
If 0.6 mg/kg of rocuronium needs to be re-administered after reversal with sugammedex. What is the minimum waiting time?
4 hours
If 0.1 mg/kg of vecuronium needs to be re-administered after reversal with sugammedex. What is the minimum waiting time?
4 hours
What drugs/conditions are relative contraindications to sugammadex?
- Contraceptives (7 days)
- Toremifene (displaces roc from sugammadex)
- Coagulopathy (↑ bleeding - not clinically significant)
What is recurarization?
Resumption of NMJ blockade after period of reversal
What s/s would indicated recurarization?
Say you just brought the patient to PACU.
- ↓ SpO₂
- ↓ respiratory effort
- Floppy/uncoordinated
- Unresponsive
What drugs and dose would be a good choice for a recurarizing patient in the PACU?
Why might this be a good choice?
- Neostigmine 0.05 mg/kg IV
- Longer duration of action
- Re-sedate the patient so they don’t remeber being paralyzed while awake
