Clinical: Farm Animal Local Blocks Flashcards
(46 cards)
1
Q
Indications for horn blocks:
A
- dehorning/disbudding
- horn injury
- inappropriate horn growth
2
Q
Cornual n. block
A
- branch of lacrimal n. which is a branch of opthalmic division of trigeminal n.
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
4
Q
Local anaesthetics for horn blocks?
A
2% lidocaine 5-10 mls (cascade)
Procaine + adrenaline (Adrenacaine)
Also give NSAID
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
6
Q
Horn blocks in goats differ from cows by…
A
- wider n. supply to horn
- horn base is larger
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
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
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
10
Q
Retrobulbar block indications
A
- enucleation sx
- corneal sx
11
Q
Drugs for retrobulbar block?
A
- 10-15 ml 2% lidocaine (Cascade)
- Procaine (Adrenacaine) - Licensed
12
Q
Retrobulbar block anaesthetises
A
cornea
lid (upper/lower)
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
14
Q
Signs of satisfactory retrobulbar block
A
- corneal analgesia
- mydriasis
- proptosis
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
16
Q
Peterson block is used for
A
Anaesthesia of the eye in cattle
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.
18
Q
Landmarks for Peterson eye block
A
- Cranially: supraorbital process
- ventrally: zygomatic arch
- Caudally: coronoid process of the mandible
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
Line block technique
* SQ inj
* Inj into deep muscle layers
26
toxic dose of lidocaine in line block for small ruminants? cattle?
Small ruminants: 5 mg/kg
Cattle: 10 mg/kg
27
Disadvantages of a line block
* poor analgesia of deep layers
* distorts Sx site
28
Inverted L Block
blocks tissue bordering caudal aspect of rib 13 & ventral aspect of transverse processes of lumbar vertebrae
29
Indications for inverted L block
* Caesarians
* some laparotomies
30
Advantages of Inverted L block
* local anaesthetic away from operating site (minimal oedema & haematoma risk)
* easy
* good when transverse process not easily palpable
31
Disadvantages of Inverted L block
* high vol of local anaesthetic
* toxicity
* increased cost
* variable analgesia, esp to deep layers
32
Proximal Paravertebral block
desensitises dorsal & ventral n. roots T13-L4
33
Proximal paravertebral block causes...
scoliosis of the spine (muscle relaxation) & warming of skin
34
How long does it take for onset of proximal paravertebral blocks?
onset 20 mins
35
How do you check the efficacy of a proximal paravertebral block?
* skin becomes hyperaemic
* local anaesthetic causes vasodilation
* lateral curvatiure of the spine towards the anaesthetised side
* test w/ forceps prior to Sx
36
Distal paravertebral block
desensitises dorsal & ventral rami of the spinal n. T13-L4
37
The distal paravertebral block does not cause
scoliosis
38
Advantages of distal paravertebral block
* lack of scoliosis
* easier
* more consistent results
39
Disadvantages of distal paravertebral block
* larger doses of anaesthetic needed
* variations in efficiency caused by variation in anatomic pathways of the nerves
40
Caudal epidural is used for...
* obstetrics
* Sx procedures involving: tail, perineum, anus, rectum, vulva & vagina, prepuce & scrotum
41
What vol of lidocaine should be used in a caudal epidural?
Lidocaine 0.5 ml/45 kg
42
IVRA (Bier Block)
Provides analgesia of the digits
43
Indications for a IVRA/Bier block
* Sx of the distal limb
44
Drug used for Bier block/IVRA
20 ml of 2% lidocaine
45
Advantages of Bier Block (IVRA)
* simple
* rapid onset & recovery
* single injection site
* minimal blood in Sx field
* may also administer antibiotics
46
Disadvantages of Bier Block (IVRA)
* lateral recumbency often req'd
* haematoma formation at site of inj
* damage to nerve underneath tourniquet
* local anaesthetic toxicity when tourniquet released
