Week 4

Question 1

Anesthetics (other than cocaine) are generally

Answer 1

vasodilators

Question 2

Name the four most widely used local anesthetic agents today. Which are esters and which are amides? Which type is most likely to cause allergies?

Answer 2

most widely used: lidocaine, bupivacaine, procaine, and tetracaine

esters: procaine, tetracaine (esters more likely to cause allergic reactions)
amides: lidocaine, bupivacaine

Question 3

What are the mechanisms of action of local anesthetics?

Answer 3

• Prevent or relieve pain by preventing the generation and conduction of nerve impulses
• Most local anesthetics, except for cocaine, promote vasodilatation by relaxation of vascular smooth muscle
 increased bleeding at the operative site and increased diffusion of the drug away from the injection site  shortened effect

Question 4

Which nerve fibers are most sensitive to actions of local anesthetics?

Answer 4

small nerve fibers are more sensitive than larger nerve fibers

Question 5

T/F:
Local anesthetics used at typical rates and concentrations wear off with time, typically with complete recovery in nerve function with no damage to nerve cells or fibers

Answer 5

True

Question 6

What can be added to tetracaine and lidocaine when used for topical anesthesia to produce vasoconstriction?

Answer 6

epinephrine

Question 7

Know the several benefits of adding epinephrine to local anesthetics

Answer 7

• Decreases bleeding making surgery easier
• Prolongs the duration of the anesthesia by retarding absorption at the site of injection
• Minimizes the amount of anesthesia needed
• Less anesthesia = decreased systemic toxicity

Question 8

Name the potential side/bad effects of local epinephrine injection.

Answer 8

the epinephrine itself may induce hypoxic damage if used in areas of the body where normally there is limited circulation – digits, nose, ears, penis and female genitalia.

Question 9

How quickly will epinephrine in a local anesthetic produce it’s full effect?

Answer 9

The anesthetic itself may have an immediate onset of action, but full vasocon-striction with epinephrine typically requires 5-10 mins

Question 10

Which type(s) preparations of local anesthetic have preservatives and which do not?

Answer 10

sodium metabisulfite and citric acid have preservatives and may prevent the degradation of epinephrine and prolong its effect

Question 11

In general, with the administration of local anesthetics, which sensation or function disappears first and which follow in what order? In what order do they return?

Answer 11

sensation of pain disappears first
followed by sense of cold and warmth
sense of touch
deep pressure
finally motor function.
Typically  these sensations will be recovered in reverse order to which they disappeared.

Question 12

What are some of the major drug interactions/bad effects with local anesthetics?

Answer 12

Cardiovascular:
Bradycardia, hypotension, cardiovascular collapse
Death due to V fib
Rare effects except for bupivacaine.
Usually only seen after high levels of systemic absorption, and after CNS effects are seen first.
Skeletal muscle:
fatigue
Smooth muscle:
temp indigestion and constipation
Skin:
hypersensitivity may manifest as atypical asthma or local dermatitis

Question 13

What is the most frequent CNS action of local anesthetics?

Answer 13

Sedation most frequent effect.

Question 14

Into which tissues is it not safe to inject local anesthetics containing epinephrine?

Answer 14

intravascular administration

Question 15

What is the purpose of adding sodium bicarbonate to local anesthetics?

Answer 15

buffering lidocaine (raises pH closer to physiologic pH--> reduced pain on infiltration)
for nerve block, alkalization --> more readily cross the nerve membrane, leading to faster onset of action

Question 16

Can sodium bicarbonate be safely added to local anesthetic products containing epinephrine? Why/why not? What are the effects?

Answer 16

epinephrine is chemically unstable in anesthetic solutions alkalinized by sodium bicarb–> don’t add it until ready fro use

Question 17

Define “infiltration anesthesia”

Answer 17

injection of a local anesthetic directly into tissue without considering the course of cutaneous nerves

Question 18

Understand the “two” definitions of a field block

Answer 18

-Injection of a combination of intradermal and subcutaneous local anesthetic solution in an inverted V just proximal to and to each side of the lesion (not into the lesion) with no attempt to locate specific nerves –> anesthetizing the region distal to the site of injection.
Blocks nerve transmission from the injected site to the brain
-Injection of a combination of intradermal and subcutaneous local anesthetic solution completely around the boundaries of the lesion, with no attempt to locate specific nerves. –> an anesthetized “field” inside of the boundaries of the anesthesia.

Question 19

What are the 2 advantages of a field block over an infiltration anesthesia?

Answer 19

• The advantage of field block over infiltration is that less drug can be used to provide a greater area of anesthesia.
• avoiding injection of anesthesia directly into the lesion avoids distortion of the anatomy of the lesion and allows the pathologist to correctly interpret the biopsy specimen.

Question 20

What are the various routes of administration of local anesthetics?

Answer 20

topical
infiltration
field block
digit block or nerve block
intravenous regional
spinal
epidural

Question 21

What are the considerations when choosing an infiltration anesthetic?

Answer 21

inject the anesthesia around/within the skin in the area to be removed or treated
may need to inject into the Sub-Q tissue and around the base of deep structures

Question 22

What are the maximum allowable safe single doses of plain 1% lidocaine and 0.25 % bupivacaine alone and with epinephrine?

Answer 22

when adding epinephrine, dec total amount by 33%

Question 23

What alternatives to local anesthesia are available when a patient is apparently allergic to the ones commonly used?

Answer 23

methyl paraben preservative free, single dose ampoules
benadryl
ehtyl chloride
no anesthetic

Question 24

Vertical mattress sutures: advantages?

Answer 24

it everts the edges better than stitches
helps to close a large area of dead space in a wound
it’s a strong stitch
used as a “stay” suture to initially align and approximate a wound to be then closed with other stitch types

Question 25

Vertical mattress sutures: disadvantages?

Answer 25

proper placement is time consuming

can result in “railroad tracking” scars if tied too tight or left in place too long