Clinical: Farm Animal Local Blocks Flashcards

1
Q

Indications for horn blocks:

A
  • dehorning/disbudding
  • horn injury
  • inappropriate horn growth
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2
Q

Cornual n. block

A
  • branch of lacrimal n. which is a branch of opthalmic division of trigeminal n.
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3
Q

Horn blocks in adults

A
  • cornual branch of intratrochlear n., branch of trigeminal
  • frontal n., branch of supraorbital n.
  • nerves are close enough together than if one n. is blocked, the other is likely to be blocked
  • Cutaneous branches of cervical n. –> SQ infiltration around the horn
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4
Q

Local anaesthetics for horn blocks?

A

2% lidocaine 5-10 mls (cascade)
Procaine + adrenaline (Adrenacaine)
Also give NSAID

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5
Q

Complications w/ horn block?

A
  • block not 100% effective (variation in path of n., inaccurate assessment of depth, pass thru apneurosis of temporalis m. caudal to ridge –> no analgesia, misplacement of needle)
  • pain on injection –> mvmt of animal –> misplacement of agent
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6
Q

Horn blocks in goats differ from cows by…

A
  • wider n. supply to horn
  • horn base is larger
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7
Q

Risk of doing horn block in neonate goat?

A
  • immature resp & CV systems
  • easily become hypothermic
  • risk of hypoglycaemia
  • sensitivity of alpha-2 agonists
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8
Q

Cornual branch of zygomaticotemporal block in goats

A
  • laterally located behind caudal ridge of supraorbital process
  • halfway btw lateral canthus & lateral edge of base of horn
  • 2% lidocaine, 2-3 ml or adrenocaine 1-1.5 cm deep w/ 22-25 G needle
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9
Q

Cornual branch block of infratrochlear nerve in goats?

A
  • medial, dorsomedial margin of orbit
  • 2% lidocaine, 2-3 ml or adrenocaine 22-25G needle at 0.5 cm depth
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10
Q

Retrobulbar block indications

A
  • enucleation sx
  • corneal sx
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11
Q

Drugs for retrobulbar block?

A
  • 10-15 ml 2% lidocaine (Cascade)
  • Procaine (Adrenacaine) - Licensed
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12
Q

Retrobulbar block anaesthetises

A

cornea
lid (upper/lower)

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13
Q

Technique of Retrobulbar block

A
  • 4-point (upper & lower lids 12/6 o’clock, lateral/medial canthus 3/9 o’clock)
  • 1-point
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14
Q

Signs of satisfactory retrobulbar block

A
  • corneal analgesia
  • mydriasis
  • proptosis
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15
Q

Complications of a retrobulbar block

A
  • Penetration of the globe
  • orbital haemorrhage
  • damage to optic n.
  • oculocardiac reflex
  • inj into optic n. meninges
  • inj into systemic circulation
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16
Q

Peterson block is used for

A

Anaesthesia of the eye in cattle

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17
Q

Peterson eye block desensitizes the nerves responsible for…

A
  • sensory & motor fxn of all structures of the eye, except the eyelid
  • Nerves: oculomotor, trochlear, abducent, trigeminal n.
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18
Q

Landmarks for Peterson eye block

A
  • Cranially: supraorbital process
  • ventrally: zygomatic arch
  • Caudally: coronoid process of the mandible
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19
Q

Indications for Peterson block

A
  • enucleation sx
  • safer than retrobulbar block
  • anaesthetises the eye & orbit w/ immobilisation of the globe
20
Q

Drug used for Peterson block

A

10-15 ml 2% lidocaine

21
Q

Auriculopalpebral anaesthetises…

A

motor nerve supply to orbicularis oculi muscle

22
Q

Localisation of auriculopalpebral

A
  • runs from base of ear aong facial crest
  • ventral to eye, giving off its branches on the way
23
Q

The auriculopalpebral provides

A
  • no analgesia
  • used in conjunction w/ topical analgesia (2% lidocaine)
24
Q

Line block

A

Infusion of local anaesthetic into the incision site to desensitise a select area of the paralumber fossa

25
Q

Line block technique

A
  • SQ inj
  • Inj into deep muscle layers
26
Q

toxic dose of lidocaine in line block for small ruminants? cattle?

A

Small ruminants: 5 mg/kg
Cattle: 10 mg/kg

27
Q

Disadvantages of a line block

A
  • poor analgesia of deep layers
  • distorts Sx site
28
Q

Inverted L Block

A

blocks tissue bordering caudal aspect of rib 13 & ventral aspect of transverse processes of lumbar vertebrae

29
Q

Indications for inverted L block

A
  • Caesarians
  • some laparotomies
30
Q

Advantages of Inverted L block

A
  • local anaesthetic away from operating site (minimal oedema & haematoma risk)
  • easy
  • good when transverse process not easily palpable
31
Q

Disadvantages of Inverted L block

A
  • high vol of local anaesthetic
  • toxicity
  • increased cost
  • variable analgesia, esp to deep layers
32
Q

Proximal Paravertebral block

A

desensitises dorsal & ventral n. roots T13-L4

33
Q

Proximal paravertebral block causes…

A

scoliosis of the spine (muscle relaxation) & warming of skin

34
Q

How long does it take for onset of proximal paravertebral blocks?

A

onset 20 mins

35
Q

How do you check the efficacy of a proximal paravertebral block?

A
  • skin becomes hyperaemic
  • local anaesthetic causes vasodilation
  • lateral curvatiure of the spine towards the anaesthetised side
  • test w/ forceps prior to Sx
36
Q

Distal paravertebral block

A

desensitises dorsal & ventral rami of the spinal n. T13-L4

37
Q

The distal paravertebral block does not cause

A

scoliosis

38
Q

Advantages of distal paravertebral block

A
  • lack of scoliosis
  • easier
  • more consistent results
39
Q

Disadvantages of distal paravertebral block

A
  • larger doses of anaesthetic needed
  • variations in efficiency caused by variation in anatomic pathways of the nerves
40
Q

Caudal epidural is used for…

A
  • obstetrics
  • Sx procedures involving: tail, perineum, anus, rectum, vulva & vagina, prepuce & scrotum
41
Q

What vol of lidocaine should be used in a caudal epidural?

A

Lidocaine 0.5 ml/45 kg

42
Q

IVRA (Bier Block)

A

Provides analgesia of the digits

43
Q

Indications for a IVRA/Bier block

A
  • Sx of the distal limb
44
Q

Drug used for Bier block/IVRA

A

20 ml of 2% lidocaine

45
Q

Advantages of Bier Block (IVRA)

A
  • simple
  • rapid onset & recovery
  • single injection site
  • minimal blood in Sx field
  • may also administer antibiotics
46
Q

Disadvantages of Bier Block (IVRA)

A
  • lateral recumbency often req’d
  • haematoma formation at site of inj
  • damage to nerve underneath tourniquet
  • local anaesthetic toxicity when tourniquet released