Anesthesia Local And Reginal Anesthesia

Front 1

What are general considerations of local anesthetics?

Back 1

-use sterile solution and injection equipment
-always aspirate before injecting
-do not inject into infected and inflamed areas

Front 2

What are local anesthetics?

Back 2

tertiary amines connected to a aromatic ring
can be aminoesters - procaine
can be aminoamindes - lidocaine

Front 3

How are local anesthetics metabolised?

Back 3

enzymatic hydrolysis is the primary metabolic pathway

aminoesters hydrolyzed by plasma cholinesterases

aminoamides undergo N dealkylation and hydrolysis in hepatic ER

Front 4

What are the onset of action and duration of lidocaine, mepivicaine and bupivicaine?

Back 4

lidocaine 3-5 minutes: 1-2 hours
mepivicaine 5-10 minutes: 1.5- 3 hrs
Bupivacaine 20-30 minutes: 4-6 hours

Front 5

What is the mechanism of action for local anesthetics?

Back 5

inhibit voltage gated sodium channels

block activation of channel and prevent depolarization of cell membrane

can be in ionized form - water soluble
unionized form - free base and lipid soluble

Front 6

What are adverse effects of local anesthetics?

Back 6

-systemic toxiciity
-direct damage to tissues-neurotoxic and myotoxic
-allergic reactions
-methemoglobinemia benzocaine (cats)

Front 7

What are the signs of CNS toxicity due to local anesthesia?

Back 7

muscle twitching and convulsions
unnconciousness
coma
respiratory arrest

Front 8

What are the signs of cardiovascular toxicity from local anesthetics?

Back 8

blockade of sodium channels in purkinkinje fibers and myocardium depresses electrophysiologic and mechanical function of the heart

sinus bradycardia and sinus arrest

toxic doses causes vasodilation and hypotension

bupivacaine is sepecially cardiotoxic

never give bupivacaine IV

Front 9

What local anesthetic should you never give IV?

Back 9

bupivicaine

Front 10

how do you treat systemic toxicity due to local anesthetics?

Back 10

support ventilation and control convulsions

Front 11

Where do you apply topical anesthesia, where is it effective?
less effective?

Back 11

applied to skin or mucous membranes

very effective on mucous membranes of eyes, nose and mouth

less effective penetration of intact skin

Front 12

Where do you apply infiltration anesthesia?

Back 12

subcutaneous injection of small volumes of local anesthetics into tissues

diffusion into surrounding tissues anesthetizing nerve fibers and endings

incisional line block (linea alba)
inverted L block
soaker catheters - intermittant injections

Front 13

What are peripheral nerve blocks?

Back 13

infection in the immediate vicinity of individual peripheral nerves or nerve plexus

used for cranial nerves, cervical and thoracic nerves
lumbar and sacral nerves

Front 14

What is an infraorbital nerve block used for?

Back 14

upper dental arcade, upper lip, nose, dorsal aspect of nasal cavity soft and hard palates

used for extraction of canines, incisors and premolars

Front 15

What is a maxillary nerve block used for?

Back 15

ipsilateral upper dental arcade, maxilla

Front 16

What is a mandibular nerve block used for?

Back 16

ipsilateral incisors, canine tooth, premolars, skin and mucosa of the chin and lower lip

Front 17

What is a mental nerve block used for?

Back 17

rostral mandible, ipsilateral canine and incisors

middle mental foramen, ventral to the lower first and second premolars

Front 18

What are examples of cervical and thoracic nerve blocks?

Back 18

brachial plexus block
forelimb nerve block
forefoot block
intercostal nerve block

Front 19

Where are the brachial plexus blocks?

Back 19

C6,C7,C8 and T1

indicated for surgeries or injuries distral to mid diaphysis of humerus

Front 20

What is a nerve stimulator?

Back 20

a current applied to the needle as it is inserted into a patient

the closer the needle is to the nerve the less current is needed to stimulate the nerve

the principle of a nerve stimulate can be used to locate any nerve not just the brachial plexus

Front 21

What are the uses of forelimb blocks?

Back 21

anesthesia of front leg distal to elbow joint-radial , ulnar and metacarpal fractures

four point block
median, ulnar, musculocutaneous nerves
radial nerve

Front 22

What are the uses of a foot block?

Back 22

provides anesthesia distal to carpus common for a declaw

insert needle on dorsomedial aspect of carpus just proximal to joint
-median nerve and palmar and dorsal cutaneous branches of ulnar

Front 23

What are the uses of lumbar and sarcal nerve blocks?

Back 23

anesthesia of hind leg distal to hip, saphenous, common peroneal and tibial nerve block

Front 24

What is the saphenous nerve and what does it do?

Back 24

saphenous = branch of femoral nerve that is sensory to medial surface of the thigh, stifle and lower leg

Front 25

What does the common peroneal nerve do?

Back 25

branch of the sciatic nerve

sensory to the dorsal aspect of lower leg

identify the fibula and inject dorsal and posterior to head of fibula

Front 26

What does the tibial nerve do?

Back 26

branch of sciatic nerve

sensory to caudal aspect of lower leg
Id medial and lateral heads of the gastrocnemius and inject in between

Front 27

What are indications for hindlimb nerve blocks?

Back 27

procedures from stifle distally (including stifle)

Front 28

What are indications of an infraorbital nerve block in large animals?

Back 28

anesthesia of upper lip and nose for suturingnasal laceration

placement of a nose ring in cattle

Front 29

What are indications of a auriculopapebral block in large animals?

Back 29

used in horses and cattle for examination and treatment of eye

blockade of auriculopalpebral nerve (motor) akinesia of eyelids

Front 30

What are the indications of the supraorbital nerve block?

Back 30

sensation to upper eyelid

nerve emerges from supraorbital foramen

Front 31

What are the indications for peterson and retrobulbar blocks?

Back 31

enucleation of eyeball, removal of tumors from eye and eyelids

Front 32

What are the indications for a caudal epidural?

Back 32

for surgical procedures involving tail, perineum, anus, rectum, vulva, prepuce and skin of the scrotum
-injection of small volume of LA into epidural space at either sacrococcygeal or first intercoccygeal space

Front 33

What are the indications for cranial epidurals?

Back 33

use lidocaine or bupivacaine

analgesia as far as T5 in dogs

dural sac closer to L7-S1 in cats

Front 34

What are contraindications of epidurals?

Back 34

sepsis
coaguopathy
local infection at site
lumbosacral fractures or dislocations
uncorrcted hypovolemia

Front 35

What are complications of epidurals?

Back 35

injection into vertebral vein
hypoventilation
apnea
hypotension