5: Local Anesthetics - Smith Flashcards
define local anesthetic
- block n conduction when applied locally to n tissue in appropriate concentrations and act on any part of nervous system and on every type of n fiber
have two “I”s in chemical name
amides
where are amides and esters metabolized?
amides - liver (i)
esters - in bloody by pseudocholinesterase
MOA anesthetics
- inhibit excitation (generation) and conduction of n impulse by increasing the threshold for depolarization
- cell membrane
- prevents increase in permeability of membranes to Na+ (sodium channels)
- can act on K+ channels
which n fibers are more sensitive to anesthetic?
small and unmyelinated
order of function
pain temp touch propioception deep pressure movement
increasing pH will ______ effectiveness of anesthetic
decrease
why use epinephrine with local anesthetic?
- increases duration of action
- decreases systemic toxicity
- provides hemostasis
where should epinephrine not be used?
ears
nose
penis
toes/fingers
concentration of epi
1:100,000 - safer at 1:200,000
dilute to 1:200,000 by (ex) drawing 5 cc of epi and lidocaine and 5 cc lidocaine
\_\_ % contains \_\_mg/ml or cc 0.25% 0.50% 1% 2%
2.5 mg/ml or cc
5
10
20
10 cc of 1% lidocaine contains _____ mg
100 mg
how many mg of drug in …
- 15cc of 2% lidocaine
- 15cc of 0.50% marcaine
- 10cc of 0.25% marcaine
- 10cc of 50/50 mix 2% lidocaine and 0.50% marcaine
- 300
- 75
- 25
- 100 lido, 25 marc
toxic dose lidocaine
4.5 mg/kg
= 300mg plain
= 500 mg w/ epi
toxic dose marcaine
2.5 mg/kgk
= 175 mg plain
= 225 mg w/ epi
