5: Local Anesthetics - Smith Flashcards Preview

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Flashcards in 5: Local Anesthetics - Smith Deck (32)
1

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

2

have two "I"s in chemical name

amides

3

where are amides and esters metabolized?

amides - liver (i)
esters - in bloody by pseudocholinesterase

4

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

5

which n fibers are more sensitive to anesthetic?

small and unmyelinated

6

order of function

pain
temp
touch
propioception
deep pressure
movement

7

increasing pH will ______ effectiveness of anesthetic

decrease

8

why use epinephrine with local anesthetic?

- increases duration of action
- decreases systemic toxicity
- provides hemostasis

9

where should epinephrine not be used?

ears
nose
penis
toes/fingers

10

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

11

__ % contains __mg/ml or cc
0.25%
0.50%
1%
2%

2.5 mg/ml or cc
5
10
20

12

10 cc of 1% lidocaine contains _____ mg

100 mg

13

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

14

toxic dose lidocaine

4.5 mg/kg
= 300mg plain
= 500 mg w/ epi

15

toxic dose marcaine

2.5 mg/kgk
= 175 mg plain
= 225 mg w/ epi

16

how many cc of 2% lidocaine plain can be given before toxic dose reached?

15cc

17

how many cc of 0.50% marcaine plain cna be give before toxic dose reached?

35 cc

18

Lidocaine/xylocaine
onset =
DOA =
risk =

3- 5 min
3-4 hr
- vfib, cardiac arrest

19

bupivacaine/marcaine/sensorcaine
onset =
DOA =

5-10 min
6-8 hr

- often mixed with lidocaine to increase DOA and prolong anesthesia

20

what could you add to make an injection less painful?

- topical refrigerant (ethyl chloride)
- sodium bicarb (buffer solution)
- also use right syringe and smallest needle
- warm the anesthetic

21

injection technique

- antiseptic
- needle inserted and wheal raised
- aspiration to prevent intravascular injection
- needle advanced forward and anesthetic deposited
- redirection of needle

22

describe mayo block/ring block

-used for bunion surgery
- proximal first interspace and advanced plantarly
- needle redirected medially along dorsal aspect of metatarsal
- needle directed from dorsal to plantar on medial side of met
- needle directed from medial to lateral on plantar side of met
- deep peroneal n block at distal interspace

"ring block around 1st met plus one more"

23

6 nerves blocked with ankle block ***

posterior tibial n.
saphenous n.
medial dorsal cutaneous n.
intermediate dorsal cutaneous n.
sural n.
deep peroneal n.

24

5 nerves blocked with ankle block ***

post tibial n.
saphenous n.
superficial peroneal n.
sural n.
deep peroneal n.

25

where do you do a post tibial n. block?

- palpate pulse of post tib a and inject POSTERIOR to artery

26

where do you do a saphenous n block?

- lateral to great spahenous v
- anterior and lateral to medial malleolus

27

where do you do a superficial peroneal n block?

- lateral to EHL tendon to get medial dorsal cutaneous n
- 1 to 1.5cm anteriro to lateral malleolus for intermediate dorsal cutaneous n

28

lemont's n

plantarflec and invert foot to visualize n

29

where do you do a sural n block?

1 to 1.5 cm posterior and inferior to lateral malleolus

30

where do you do a deep peroneal n block?

- inject b/w EDL and EHL just lateral to ant tibial a (palpate pulse)

31

what is an infiltration block?

injection of anesthetic directly at procedure site for example, excision of wart of biopsy

32

complications assoc with local anesthetics

- syncope
- allergic rxn
- arrhythmia (PVC, lwo pulse, low oxygen, chest pain, vfib)
- cardiac arrest

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