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47 Cards in this Set
- Front
- Back
- 3rd side (hint)
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first local anesthetic
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cocaine in 1855
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first used as nerve block
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1884
Dr. William Halsted/Hall cocaine for nerve block |
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1891 lumbar puncture for?
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hydrocephalus
Dr. Quinke |
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first synthesized local
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procaine(novacaine)
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introduced caudal epidural anes
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Ferdinand Cathelin and Jean Sicard circ.1901
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introduced lumbar epidural anes
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Fidel Pages circ 1921
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most recent local anes developed
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ropivacaine-deriv of bupivacaine, but less cardiotoxic
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char. of locals
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poorly H20 sol
weak base benzoic acid joined by ester linkage to tert amine |
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3 parts of local makeup
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hydrophilic chain(tert amine)
lipophilic (aromatic ring) ester or amide linkage |
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ester locals
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cocaine
procaine chloroprocaine tetracaine |
4 of them
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amide locals
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mepivacaine, ropivacaine, Bupivacaine, lidocaine, etidocaine, prilocaine
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Mr. Blep
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char of locals
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less stable-shorter shelf life
met by pseudocholinesterase most likely to cause allerg rx |
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char of amides
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more stable
met by liver rare allergies |
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importance of acid preparation
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highly ionized-portion is h20 soluble.
epi(if added) needs acidic environment. not stable in alk |
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mech of locals
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Na channel blockers
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blocks Na from?
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inside the channel
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nonionized vs ionized portion of local structure
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non crosses axonal membrane..
ionized cation is resp for blockade |
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base form of locals keeps the Na gate in what state?
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closed inactive
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locals (do/do not) alter resting membrane potential?
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do NOT. it slows the rate of depolarization so threshold potential is not reached
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Cm=
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minimum concentration. minimum amount needed to produce block
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Cm influenced by-
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potency of local
nerve diameter myelenated or not "frequency dependant block principle" position of nerve in bundle |
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frequency dependant blockade
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the more a nerve fires, the more sensitive to local block
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myelinated vs nonmyelinated
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non is quicker unless rapid firing
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nerve fibers classified by
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nerve fiber diameter and conduction velocity
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Largest diameter nerves are?
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A fibers
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A-alpha
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innervate skeletal muscle for motor and proprioception
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A-beta
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sensation of touch and pressure
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A-gamma
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skeletal muscle of muscle tone
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A-delta
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pain, temp, touch
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B-fibers
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preganglionic autonomic.
blocked first |
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A-delta and C fibers
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blocked at same time and then the rest of the A fibers
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Potency of local rel to ?
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lipid solubility
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onset of local rel to
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pKa
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absorp of locals in order...
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IV, intercostal, tracheal, caudal/cervix, epidural, brachial plexus, spinal, subQ
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active metabolite of lido
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mono ethyl glycine xylodide
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metabolite of prilocaine
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ortho toluidine. causes metHgb
reduces Fe2+ to Fe3+ |
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s/s of local toxicity-in order of severity
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numbness of lips/tongue, lightheaded, visual/hearing disturbances, muscle twitches, unconsciousness, convulsions, coma, resp collapse, CV collpase
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tx of local tox
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O2
benzo's barbs all increase the seizure threshold, and airway managemnt |
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CV s/s of local tox
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initial tachy and hypertension
then brady and hypo with dec. CO |
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tx of CV s/s of local
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epi, ephedrine, atropine, bretylium, extend the CPR time
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PABA
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para aminobenzoic acid
from the esters |
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dibucaine 80
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normal. dibucaine is 80% depressed. # is the % inhibition of pschase
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dibucaine 40
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heterozygous (1 of each gene)
20-30 block |
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dibucaine 20
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homozygous (two genes) profound extended block. up to 8 hours
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atypical pseudocholinesterase
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incapable of hydrolyzing ester locals
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tx for metHb
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methyline blue at 1-2 mg/kg over 5 minutes
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agent in diluents that causes rxns
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parabens-cytotoxic. use preservative free or MPF
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