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My 2016 RUSVM Anesthesia > Locoregional Anes SA & LA > Flashcards

Locoregional Anes SA & LA Flashcards

1
Q

typical LA techniques

A

topical

SQ

Line block

wound soaker catheter

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2
Q

Topical anesthesia

A

EMLA cream (2.5% lidocaine + 2.5% prilocaine)

  • 60 min before full onset, occlusive dressing
  • IVC placement

Lidocaine patch (5% lidocaine)

  • analgesic effect, not complete block
  • placed on incision after closure

Ophthalmic

  • Tetracaine or proparacine

Laryngeal

  • 0.1 mL 2% lidocaine (feline intubation)
  • topical to arytenoids
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3
Q

SQ

A

use for wounds, masses, skin biopsy

  • Ventral midline line block*
  • infliltrate SQ & muscle layers
  • Wound soaker catheter*
  • placed during sx, deep aspect close to visualized nerves
  • delivers consisten 7 prolonged (1-2d) analgesia
  • used for TECA, Amputation , oncologic sx, lg wound closure
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4
Q

IVRA aka “Bier block”

A
  • used for distal extremity
  • procedure 60-90 mL
  • complications: tourniquet pain, ischemia/nerve inj, limb swelling, hematoma, LA toxicity
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5
Q

peripheral nerve blocks - head

A

Retrobulbar block
Maxillary n. block
Infraorbital n. block
Inferior alveolar n. block
Mental n. block

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6
Q

retrobulbar block

A

Indications:

  • Enucleation
  • Evisceration/prosthesis
  • Intraocular surgery

Nerves affected:

  • CN II, III, IV, V, VI, ciliary ganglion (parasympathetic)

Advantages:

  • Post-op analgesia
  • Globe immobility during surgery
  • Decreased anesthetic and NMBD requirements

Complications:

  • Retrobulbar hemorrhage
  • Damage to optic nerve, extraocular mm.
  • Globe penetration
  • Intravascular injection
  • Intrathecal injection (into optic nerve/subarachnoid space)

Preferred technique:
Inferior-temporal palpebral

  • High resistance to injection indicates positioning within optic nerve sheath – injection may be fatal
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7
Q

Peripheral nerve blocks - thoracic limb

A

Cervical paravertebral block
Brachial plexus block
RUMM block
“declaw” block – distal radial, ulnar, median

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8
Q

cervical paravertbral block

A
  • Less common block
  • Technically difficult
  • Anesthesia for entire thoracic limb incl. scapula and shoulder joint
  • Ventral branches of C6, C7, C8, and T1 spinal nerves, proximal to brachial plexus
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9
Q

Brachial plexus

A

Anesthesia distal to and including the elbow

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10
Q

RUMM block

A
  • Anesthesia for “distal thoracic limb”

(depends on accuracy of perineural injection)

  • Radial, _u_lnar, median, and musculocutaneous nerves
  • Requires 2 injection sites, one medial and one lateral
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11
Q

block for declaw

A

A pre-anesthetic block is indicated for intra- and post-op analgesia
Bupivacaine 1 mg/kg divided between sites, can dilute 1:1 with salin

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12
Q

Peripheral nerve blocks – pelvic limb

A

Femoral and sciatic nn.
Must be performed together for complete stifle block
Anesthetizes distal to mid-femur
As effective as epidural for stifle surgery

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13
Q

Intercostal n. block

A
  • Anesthesia for thoracotomy, rib fractures, etc.
  • Nerves run w/ artery and vein along CAUDAL aspect of rib
  • Block at the incision space, and 2 spaces cranial and caudal (5 total)
  • Aspirate before injection, avoid thoracic cavity
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14
Q

Intrapleural regional

A
  • Local anesthetic injected into thoracic cavity
  • Often delivered through indwelling chest tube post-thoracotomy
  • Consider gravity!
  • Affected side down for at least 20 mins after injection
  • Generally safe and effective
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15
Q

Epidural

A
  • Most commonly performed at the L-S space in small animals
  • Requires heavy sedation or anesthesia
  • Anesthesia caudal to umbilicus (generally)

Two options:

  • Single injection (most common)
  • Epidural catheter
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16
Q

Epidural – positioning

A
  • Depends on anesthetist preference and patient condition

Sternal recumbency

  • Easier to palpate landmarks
  • Legs pulled forward (hips flexed) to maximize L-S space
  • Allows hanging drop technique

Lateral recumbency

17
Q

Epidural injection volume

A
  • Higher volume → more cranial drug spread
  • Concern for sympathetic blockade and hypotension with local anesthetic
  • Volume 0.2 mL/kg will reach L1
  • Sufficient for caudal abdomen, pelvic limbs, perineum
18
Q

epidural drugs

A

Most commonly a local anesthetic + opioid

Bupivacaine + morphine

  • This combo may provide analgesia for up to 24 hours

Morphine is less lipid soluble than other opioids

  • More cranial spread
  • Longer duration of action
  • Morphine L-S epidural can provide analgesia to thoracic wall and thoracic limbs
19
Q

epidural complications

A

Intrathecal (spinal) injection
Use ½ volume if CSF is obtained
Neural damage/toxicity
Use preservative-free, “for epidural use”
Infection
Sterile technique
Hypotension
Fluids and/or vasopressors

20
Q

epidural opioids complications

A

Urinary retention
Express bladder post-operatively
Monitor closely for urination before discharge
Pruritis – uncommon

21
Q

Equine eye

A

Auriculopalpebral n. block

  • Prevents blinking – allows ophthalmic exam
  • MOTOR BLOCK ONLY

Supraorbital n. block

  • Sensory to middle 2/3 of upper eyelid and palpebral motor
  • Used for placement of sub-palpebral lavage catheter (common use)

Retrobulbar block

  • transpalpebral most common
  • Most commonly used for standing enucleation
22
Q

Equine epidural anesthesia

A
  • Caudal (not lumbosacral) epidural
  • Do not want to lose hind limb motor function

Uses:

  • Control of rectal tenesmus
  • Correction of uterine torsion, fetotomy, obstetric manipulations
  • Tail amputation, rectovaginal fistula repairs, Caslick’s procedure
  • Hindlimb procedures and pain (but do not use local anesthetics → motor blockade)

Location:

First coccygeal space
(Co1-Co2)
First movable articulation when tail is raised and lowered

23
Q

Equine epidural anesthesia – drugs

A

Local anesthetics:
Remember – these cause motor blockade
Excessive cranial spread to spinal cord segments innervating the pelvic limbs ⇒ hindlimb ataxia or mm. weakness
EXTREMELY DANGEROUS IN A HORSE
Lidocaine 2% 6-8 mL in an adult horse is adequate for anus, perineum, rectum, vulva, vagina, urethra, bladder

Alpha-2 agonists:

Xylazine, detomidine (common)

Causes local analgesia and systemic alpha-2 effects (sedation, 2nd degree AV block, ataxia, etc)

Opioids:

Morphine

  • Provides analgesia
  • No risk of weakness or motor blockade
  • Often administered through epidural catheter for longerterm (days) analgesia
  • Hindlimb trauma, surgery, severe laminitis

Side effects: urticaria, ileus
Detomidine + morphine
Common combination
Can provide excellent analgesia for hindlimb pain

24
Q

Local anesthesia for castration

A

Commonly used for adjunctive analgesia
Allows lower dose of general anesthetics
~20 mL lidocaine injected into each testicle

Should feel firm after injection
Quickly diffuses into spermatic cord to provide anesthesia

25
Q

Line block

A

Lidocaine injected along proposed incision line

26
Q

Inverted L block

A

Lidocaine injected into area dorsocaudal to last rib and ventrolateral to lumbar transverse processes

27
Q

Proximal paravertebral thoracolumbar

A

Anesthetizes dorsal and ventral branches of T13, L1, L2 spinal nn.
Injection site 3-5 cm from dorsal midline, majority of drug deposited
at VENTRAL aspect

Disadvantages:
Technical difficulty (esp. fat cattle)
Scoliosis may cause difficulty closing incision
Risk of penetrating great vessels
Loss of motor control if LA migrates to femoral nn.

28
Q

Distal paravertebral thoracolumbar

A

Dorsal and ventral branches of spinal nn. T13, L1, L2
Dorsal and ventral to transverse processes of L1, L2, and L4

Advantages over proximal paravertebral:
Lack of scoliosis
Less risk of penetrating major blood vessels

29
Q

Caudal epidural

A

Obstetric manipulations and surgical procedures for tail, perineum, anus, rectum, vulva, vagina, prepuce, scrotum
Commonly and easily performed
S5-Co1 or Co1-Co2 space

Remember that total dose (volume x concentration) effects the cranial spread and extent of anesthesia
Local anesthetics, alpha-2 agonists, morphine

30
Q

Lumbosacral epidural

A

Good for immature cattle, small ruminants, camelids, and pigs
(generally not for adult cattle)
L6-S1 space
Alpha-2 agonists commonly utilized
Similar technique as for dogs

31
Q

Teat

A

Local anesthesia

  • Ring block
  • Inverted V block
  • Teat cistern infusion
  • IV regional anesthesia of the teat
32
Q

Udder

A

Paravertebral block of L1, L2, L3

  • Cranial aspect of udder and teats

High caudal epidural

  • Caudal aspect of teats and udder
33
Q

Foot

A

Common site of injury or disease

  • Ring block

OR

  • IVRA (similar technique as in small animal)
34
Q

Testicular block for castration

A

Cattle, goats, sheep, swine
Lidocaine most common
Volume dependent on size of patient
Be cognizant of the maximum systemic dose, especially for smaller
animals

My 2016 RUSVM Anesthesia (22 decks)

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