Neuromuscular Reversal Flashcards
Reversal of Nondepolarizing drugs
ANTICHOLINESTERASES: ?
__ ammonium compounds
Allow __ at NMJ
Neostigmine & pyridostigmine- ? Bind to esteric site of ____
Endrophonium- electrostatic attachment to ___ site of the enzyme-reversible H+ binding
ANTICHOLINESTERASES: Neostigmine, pyridostigmine, endrophonium
Quaternary ammonium compounds
Allow ↑Ach at NMJ
Neostigmine & pyridostigmine- covalent binding of carbamyl group. Bind to esteric site of acetylcholinesterase.
Endrophonium- electrostatic attachment to anionic site of the enzyme-reversible H+ binding
Goal of reversal
what are the two goals?
These goals are accomplished by ___ the competitive effect of the NMB & ____ the concentration of Ach at the NM junction
Re-establish spontaneous ventilation
Protect the airway from aspiration
These goals are accomplished by ↓ the competitive effect of the NMB & ↑ the concentration of Ach at the NM junction
Time to Recovery
Composite of : 1. Antagonism & 2. Spontaneous recovery Factors influencing: 1. Degree of \_\_; 2. ?; 3. blood levels of \_\_; 4. infusion vs. \_\_ ; 5. specific \_\_\_ used & dose; 6. underlying \_\_\_\_; 7. drug interactions (enflurane> isoflurane> halothane); 8. ?; 9. ?; 10. age - Elderly: The lower the muscle mass, the greater the intensity of the block.
Composite of : 1. Antagonism & 2. Spontaneous recovery
Factors influencing: 1. Degree of paralysis; 2. pharmakokinetics/dynamics; 3. blood levels of relaxant; 4. infusion vs. bolus; 5. specific antagonist used & dose; 6. underlying NM dysfunction; 7. drug interactions (enflurane> isoflurane> halothane); 8. organ dysfunction; 9. acid-base disturbances; 10. age
Neostigmine:
____ used & is most reliable in ___ block >90%.
Not reliable in ____ block (100%)
Increasing dose over ____ DOES NOT increase effectiveness (ceiling effect)
Onset __min
Peak ___ min
Glycopyrrolate - onset and duration similar (peaks 3-5 min vs. 1-2 atropine)
Mixture ____ Neo + _____ glycopyrrolate
Metabolized by cholinesterases in _____
Principle route of excretion is the ____
Most commonly used & is most reliable in deep block >90%. Not reliable in profound block (100%)
Increasing dose over 0.07-0.08mg/kg DOES NOT increase effectiveness (ceiling effect)
Onset 3 min
Peak 7-10 min
Glycopyrrolate - onset and duration similar (peaks 3-5 min vs. 1-2 atropine)
Mixture 0.05-0.07 mg/Kg Neo + 0.01-0.02 mg/ kg glycopyrrolate
Metabolized by cholinesterases in NMJ and liver
Principle route of excretion is the kidney
hOW DO YOU CALCULATE NEOSTIGMINE DOSE?
3-4 CC PER 70-80 KG and then draw up the same amount of glyco. administer in same syringe.
ACh at NMJ has nicotinic effects as well as where else?
peripheral nervous system. driven by muscarinic receptors.
Pyridostigmine \_\_ as potent as neostigmine \_\_\_ onset 40% \_\_\_ Peak effect \_\_ min (can be as long as 15-20 min) Mix w/ \_\_\_ \_\_\_\_ dose Oral for \_\_\_\_ Most dependent on \_\_\_ clearance 75%
20% (1/5th) as potent as neostigmine slower onset 40% longer duration Peak effect 12 min (can be as long as 15-20 min) Mix w/ glycopyrrolate 0.14-0.25 mg/kg dose Oral for myasthenia gravis Most dependent on renal clearance 75%
Endrophonium
adequate reversal if all \_\_\_ \_\_ potent (\_\_\_ of neostigmine) \_\_\_ onset peak \_\_\_ min ↑ Ach release \_\_\_synaptic less severe \_\_\_ effects Typically administered w/ \_\_\_\_ (.01 mg/kg) =onset times \_\_\_\_ dose
adequate reversal if all 4 twitches present least potent (1/10th of neostigmine) fast onset peak 1-2 min ↑ Ach release presynaptic less severe muscarinic effects Typically administered w/ atropine (.01 mg/kg) =onset times 0.5-1.0 mg/kg dose
Clinical Effects of increased Ach
Effects occur fastest for ? Cardiovascular Muscarinic effect –? Pulmonary: Muscarinic effect - ? GI: ? Cerebral \_\_\_ crosses BBB
Effects occur fastest for endrophonium->neostigmine ->pyridostigmine Cardiovascular Muscarinic effect – bradycardia/ vagal stimulation Pulmonary Muscarinic effect - bronchospasm GI Increased peristalsis and secretions N/V Fecal incontinence Cerebral Physostigmine crosses BBB
Use extreme caution with (endrophonium, neostgmine, pyridostigmine) in people who have what diseases?
rate dependent cardiac disease (worried about the pt dropping their HR too much)
asthma
bronchospastic disease
___ are NOT given alone, use in combo with antimuscarinic
anticholinesterases
Anticholinergics/antimuscarinics
___ competitively bind to muscarinic Ach receptors
Prevents ____ mediated effects
Atropine & scopolamine are ___ amines- cross the Blood Brain Barrier (BBB)
Glycopyrrolate is a ____ amine- ionic charge ____ passage across BBB
aromatic esters competitively bind to muscarinic Ach receptors
Prevents cGMP or cAMP mediated effects
Atropine & scopolamine are tertiary amines- cross the Blood Brain Barrier (BBB)
Glycopyrrolate is a quarternary amine- ionic charge minimizes passage across BBB
Anticholinergics (Antimuscarinics)
Atropine- Onset __ / Duration ___
Glycopyrrolate- Onset ___/ Duration ___
With edrophonium – give several minutes prior to prevent ____
Scopolamine:
Not used in ?
Good for ___ and as an ____
Atropine- Onset 1 min/ Duration 30-60 min
Glycopyrrolate- Onset 2-3 min/ Duration 2-4 hours
With edrophonium – give several minutes prior to prevent bradycardia
Scopolamine
Not used in reversal of NDMR’s
Good for sedation
Good as an antisialagogue
Easy calculation:
for every cc of ___ draw a cc of __ in same syringe
neostigmine, glycopurrolate
mixture: 0.05 mg/Kg Neo + 0.01 -0.02 mg/kg glycopyrrolate
70kg x 0.05 neostigmine = 3.5 mg (draw 4 cc=4mg) + 4cc glycopyrrolate (4x 0.02 =0.08 mg)
When do we reverse?
MUST have at least one twitch present on PNS (peri nerve stimulator)
When was last dose of NDMR given???
Will the patient be intubated post-op?