Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Pharm Test 2 > Local anesthetic blocks > Flashcards

Local anesthetic blocks Flashcards

1
Q

mechanism of action of local anesthetics

A
  • Bind to Na+ channels
    – Prevent Na+ from entering the cell
  • Impede propagation of action potentials
    – Cause a conduction blockade
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

chemical structure of local anestheitcs

A

aromatic ring: lipophilic
intermediate chain: (amide are the ones in current use)
amine: hydrophilic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Lidocaine onset time (min), duration (min), and clinical dose (mg/kg)

A

onset: 5-10
duration: 60-90
clinical dose: 2-5

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Mepivicaine onset time (min), duration (min), and clinical dose (mg/kg)

A

onset: 5-10
duration: 90-120
clinical dose: 2-5

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Bupivicaine/Ropivicaine onset time (min), duration (min), and clinical dose (mg/kg)

A

onset: 20-30
duration: 240-360
clinical dose: 1-2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what type of fibres do local anesthetics block?

A

-every fibre
-notable for pain:
>A-delta (fast pain, temp)
>C (slow pain)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

active form vs diffusible chemical form of local anesthetic

A

DIffusable: RN
Active: RNH+

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

common uses for local anesthetics, and how they are performed

A

A. Analgesia/Anesthesia blocks for surgical procedures
* Peripheral administration
* Combined with Sedation or General Anesthesia

B. Equine lameness diagnosis

C. Lidocaine, intravenously
* Analgesic and MAC (minimum alveolar concentration) sparing effects of inhalant anesthetics

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

advantages of local anesthetics

A
  1. Used in standing animal (Large Animals)
  2. Used with sedation only
  3. Easy to perform
  4. decreased resistance/movement
  5. Inhibition of nociception
    – Transduction
    – Transmission
    – Modulation (epidural, IV administration)
  6. Reduced level of GA / sedation allows for:
    – decreased adverse cardiopulmonary effects
    – decreased doses of analgesics intra- and postoperatively and their side effects
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

complications with local anesthetic use

A
  1. Toxicity
    -unintentional IV injection
    -excessive doses
    >toxicity dependent on several factors not just dose
  2. Damage to surrounding structures
    -traumatic technique, sepsis
  3. Failure of technique
    -lack of experience, anatomical abnormalities
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

how do ester vs amide local anesthitics differ in their toxicities?

A
  • Esters = allergic reactions
  • Amides = CNS, CV toxicity
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

2 examples of ester local anesthetics

A

Procaine, Tetracaine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

describe the toxic process of an ester local anesthetic

A

– Hydrolysed by plasma cholinesterase
* Metabolite:Para-aminobenzoic acid (PABA) which is allergenic
* Chloroprocaine and tetracaine do not result in PABA
* Cocaine- also to norcocaine via N-demethylation
– USED LESS frequently nowadays

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

describe the toxic process of an amide local anesthetic

A

– Enzymatic degradation in liver
* N-dealkylation and Hydroxylation
– Then glucoronidation (cats are defficient)
* Metabolite: Aminocarboxilic acid and a cyclic aniline derivative

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

examples of amide local anesthetics

A

Lidocaine, Mepivacaine, Bupivacaine, Ropivacaine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

toxicity of a local anesthetic mainly depends on what?

A

Toxicity = Due to plasma concentrations

-Depends on dose, site of administration, co- administration of other drugs, individual variation
-Depends on rate of absorption in area & vasculature
-Toxicity is additive if using more than one local anesthetic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

what kind of effects can toxic doses have in conscious animals?

A
  • Toxic doses cause excitatory effects in conscious animals
    – CNS- seizure activity
    – CVS- Arrhytmias
    – Lead to death
18
Q

what kind of effects can toxic doses have in anesthetized animals?

A
  • Toxic doses cause depressive effects in anesthetized animals
    – Up to 2X blood concentration reached using same dose
    – No deaths
19
Q

signs of anesthetic toxicity in dogs in order of appearance

A
  • Tremors
  • Rigidity
  • Salivation
  • Convulsions
  • Sedation
  • Convulsions
  • Arrhythmias- more likely with bupivacaine
  • Cardiac arrest
20
Q

CONTRAINDICATIONS TO LOCAL ANESTHETIC USE

A
  1. Infection
  2. Previously reported allergic reaction to the drug
21
Q

general rule for local anesthetic dose?

A

– General rule is 0.2 mL/kg
* 4 mg/kg for 2% lidocaine
* 1 mg/kg for 0.5% bupivacaine
– Depending on specific block volume may be ­ or ̄ from this rule

22
Q

4 classifications of blocks

A
  1. Terminal Anesthesia
    a. Topical/ surface
    b. infiltration or incisional
  2. Regional
    a. Field block
    b. Peripheral nerve
  3. Spinal/Epidural
  4. IV Regional
23
Q

what does a terminal local anesthetic block do? what are the subcategories?

A
  • Blocks the nerve endings at the site of interest
    >blocks transduction

a. Topical/ Surface
o Corneal block
o Laryngeal spray

b. Infiltration or Incisional
o Infiltration- Injection of the local along incision line
o Incisional- Goes through all of the layers

24
Q

how do we perform a topical local anesthetic block for the conjunctiva/ cornea? why?

A

– Local application of proparacaine (0.5%) into conjunctival sac
– Onset 1-6 minutes
– Duration 10-15 minutes
* Examination of painful eye, removal of foreign bodies, conjunctival scrapings, subconjunctival injections

25
Q

why would we apply a topical local anesthetic to the laryngeal opening? what would we use?

A

Lidocaine spray
– Local application of lidocaine onto laryngeal opening
* To facilitate endotracheal intubation
* Frequently done in cats

26
Q

what type of local anesthetic block is testicular injection? how would we perform this?

A

Testicular injection
– (equine/bovine/porcine, dogs)
– Lidocaine (10-20 mL equine/bovine; 5-10mL porcine; 1-2 mL dog)
* Fast acting
* Duration of effect is adequate for procedure
– Deposited into spermatic cord / testicular tissue

27
Q

incisional line block for laparotomy is what type of block?

A

topical

28
Q

what is a regional local anesthetic block? what are the subcategories?

A

Technique used to provide anesthesia to a “region” using specific nerve block(s)
-blocks transduction and transmission

Terms used to describe this:
a. Field block - block a path of nerves
b. Peripheral nerve block – block the actual nerve

29
Q

what is a field block? what other technique is it similar to? what is an advantage? what are some examples?

A
  • Innervation blocked a distance from the operation
  • Same technique as for infiltration
    – Less chance for interference with healing
  • Inverted L block (ruminant)
  • Ring block of limb (SA, ruminant)
  • Ring block of the teat (ruminant)
  • Brachial plexus block (SA, LA)
30
Q

where do we inject for a field block of the brachial plexus? (what nerve rami)

A

Nerve rami: C6-8, T1

31
Q

what nerves is it important to block when dehorning cattle or goats?

A
  • Cornual nerve in cattle - dehorning
    – Cornual (Zygomaticotemporal)
    – Supraorbital
    – Infratrochlear
    – Branches from C2

– Goats dual supply
* Zygomaticotemporal and Infratrochlear

32
Q

what nerves do we block for Proximal Paravertebral Thoracolumbar Anesthesia? where do we place the needles?

A
  • Blocks dorsal and ventral branches of:
    – T13, L1, L2, L3 spinal nerves

*Sites to place needle
- L1, L2, L4

33
Q

purpose of the Auriculopalpebral peripheral nerve block?

A

(motor blockade)
* Frequently utilized, extremely effective, facilitates surgery by minimizing eyelid movement (blinking)

34
Q

femoral nerve is what spinal segments?

A

L4,5,6

35
Q

sciatic nerve is what spinal levels?

A

L6,7

36
Q

what is an epidural? how does it compare with a spinal block? what part of the signal do these block?

A

-spinal block is applied into spinal canal, epidural is in epidural space
-epidural is most commonly used in veterinary medicine
>requires a higher dose than spinal

-blocks transmission, modulation, projection

37
Q

where should we never give an epidural dose?

A

the intrathecal space

38
Q

what parts of the large animal does a caudal epidural block? what drug do we usually use and why? dose?

A
  • Surgical anesthesia of the anus, vulva, vagina, perineum, rectum, tail

– Lidocaine used for faster onset time
* 1ml/100 kg (bovine; equine)
– Careful above 4-5 mL in horses
– Ruminants tolerate higher volumes
* 0.5-1 ml /50 kg (small ruminant)
* Overdose induces recumbency due to motor blockade

39
Q

where can we give an epidural?

A

-caudal to L6
-caudal to sacrum
-between Co1 and Co2

40
Q

what species do we use a lumbosacral epidural? what does it do? what can we give in combination to prolong analgesic effects? what else will this substance help with? what local anesthetics do we usually use for epidurals?

A

Calves, Small Ruminants, and Small Animals

  • Provides hindlimb & caudal abdominal anesthesia
  • Opioids in combination with local anesthetic – may prolong analgesic effects & reduce systemic side-effects
  • Lidocaine or bupivacaine
    – Bupivacaine typically used clinically for duration
    – 0.2 mL/kg
  • 4 mg/kg of 2% lidocaine, or
  • 1 mg/kg of 0.5% bupivacaine
41
Q

how many lumbar vertebrae do cows have?

A

6

42
Q

how many lumbar vertebrae do dogs and cats have?

A

7

Pharm Test 2 (16 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions