Neuromuscular Blockers Flashcards
Where is the best place to measure onset of blockade?
- muscle = orbicularis occult (closes lid) or corrugator supercilii (eyebrow twitch)
- nerve = facial nerve
Where is the best place to measure recovery of blockade?
- muscle = adductor pollicis (thumb adduction) or flexor hallicus (big toe flexion)
- nerve = ulnar nerve or post tibial nerve
How does succs cause bradycardia?
stimulates the M2 receptor on the SA node
Does succs cause tachycardia?
- yes
- it mimics action Ach at the sympathetic ganglia
- can cause tachycardia and HTN
- causes tachycardia in adults more than bradycardia
How does succs affect intraocular pressure?
it increases intraocular pressure by 5-15 mmHg for up to 15 min.
How does succs affect intracranial pressure?
- it temporarily increases intracranial pressure
- minimized or prevented by a defasciculating dose
How does succs affect intragastric pressure?
- causes contraction of abdominal contents
- increases lower esophageal sphincter tone
- these 2 cancel each other out and therefore the pressure is unchanged
Do you cancel the case if the pt has a masseter spasm after succs?
- No, not if it happens in the absence of other s/sx of MH
- succs is a trigger of MH
What metabolizes acetylcholine?
- Type 1 cholinesterase
- Acetylcholinesterase
- True cholinesterase
- Specific cholinesterase
- Genuine cholinesterase
What metabolizes succs, mivacurium, and ester LAs?
- Type 2 cholinesterase
- Butyrylcholinesterase
- False cholinesterase
- Plasma cholinesterase
- Pseudocholinesterase
What are drugs that reduce Pseudocholinesterase activity?
- Metoclopramide
- Esmolol
- Neostigmine (NOT edrophonium)
- Echothiophate
- Oral contraceptives / estrogen
- Cyclophosphamide
- Monoamine Oxidase Inhibitors
- Nitrogen mustard
What are co-existing conditions that reduce Pseudocholinesterase activity?
- Atypical PChE
- Severe liver disease
- Chronic renal disease
- Organophosphate poisoning
- Burns
- Neoplasm
- Advanced age
- Malnutrition
- Pregnancy (late stage)
Who is at risk for post-op myalgia with Succs?
- young adults undergoing adulatory surgery (women > men)
- those who do not engage in routine strenuous activity
How can post-op myalgia from Succs be reduced?
- it may be reduced by pretreatment with a NDNMB
- on tenth of the ED95 of a NDNMB can reduce fasciculations
- should be administered 3-5 min before succs
What is Hoffman Elimination dependent upon?
- normal blood pH and temperature
- rxn is faster w/ alkalosis and hyperthermia
- rxn is slower w/ acidosis and hypothermia
Does mivacurium produce an active metabolite?
No
What drugs potentiate NMBs?
- volatile anesthetics (Des>Sevo>Iso>N2O>Propofol)
- Antibiotics (Aminoglycosides, Polymyxins, Clindamycin, Lincomycin, Tetracycline)
- Antidysrhythmics (verapamil, amlodipine, lidocaine, quinidine)
- local anesthetics (probably all of them)
- Diuretics (furosemide)
- dantrolene, cyclosporine, tamoxifen
What electrolyte imbalances potentiate NMBs?
- inc lithium (activates K+ channels)
- inc Mg (dec Ach release from presynaptic nerve)
- dec Ca+2 (dec Ach release from presynaptic nerve)
- dec K+ (dec resting membrane potential)
What patient factors potentiate NMBs?
- hypothermia (dec metabolism and clearance)
- women (women are more sensitive to the effects of NMBs compared to men)
A patient with what type of condition should not receive pancuronium?
- hypertrophic cardiomyopathy
What is the order of highest to lowest likelihood of NMBs that produce anaphylaxis?
succs > atracurium > cisatracurium > rocuronium > vec
