Local Blocks to diagnose lameness Flashcards
what does abaxial/basisesamoid block anesthetize? (6)
Distopalmar P1 and down
- distopalamar P1
- P2
- proximal and dital interphalangeal joints
- distal SDFT/DDFT
- distal sesamoidian ligament
- digital annular ligament
landmarks for abaxial/basisesamoid block
abaxial border of each proximal sesamoid bone right along vascular bundle
criteria for using local blocks to diagnose lameness (3)
- is the horse lame enough? (not good for intermittent lameness)
- is the horse too lame? can risk injury/fracture
- will the horse tolerate the needle?
lateral palmar nerve block: where is it inserted and in what direction?
mediolateral direction on the medial side of the accessory carpal bone
done while weight bearing
High 4 point block anesthetizes…(3)
- suspensory ligament
- some flexor tendons
- some of MCIII and MCIV
reasons PD nerve block might fail (5)
- adhesions between navicular bone and DDFT
- OA of coffin
- concurrent proximal disease (suspensory apparatus issue)
- old anesthetic used
- accessory nerve supply from dorsal branches
what to remember when using low 4 point block on hindlimb?
must also direct and inject a little cranially
what position are abaxial/basisesamoid and PD nerve blocks administered?
hold limb up/non weight bearing
agents used for local blocks in equines (3)
- 2% lidocaine: cheap but burns; lasts 30 mins-2hours
- 2% mepivacaine/carbocaine: G.S. lasts 30mins-2hours; once open goes bad within 5-7 days; don’t let freeze
- 0.5% bupivacaine/Marcaine: duration 5-6 hours; only for shoeing/therapeutic; NOT for diagnostics
which nerve/nerves is targeted by abaxial/basisesamoid block and PD block?
palmar digital nerves
lateral palmar nerve block blocks _____
origin of suspensory ligament
which nerve block:
- distopalamar P1
- P2
- proximal and dital interphalangeal joints
- distal SDFT/DDFT
- distal sesamoidian ligament
- digital annular ligament
abaxial/basisesamoid block
which injection for the low 4 point block is more proximal and why?
-lateral and medial palmar nerves: between suspensory ligament and DDF (more proximal to avoid tendon sheath/flexor manica)
how much do you inject for low 4 point block?
- lateral and medial palmar nerves: between suspensory ligament and DDF (more proximal): 3 mL
- Lateral and medial palmar metacarpal nerves: find button on MIV and go just distal: 1 mL
needle usually used for nerve blocks?
25-23 G
which nerve block: coffin joint and down: -sole -navicular apparatus -soft tissues of heel -coffin joint -digital portion of DDFT
PD block
structures anesthetized by PD nerve block (5)
coffin joint and down:
- sole
- navicular apparatus
- soft tissues of heel
- coffin joint
- digital portion of DDFT
how long do most nerve blocks take before they have effect?
3-5 mins
intra-articular anesthesia: what to remember? (6)
- insert needle WITHOUT syringe
- collect synovial sample prior to anesthetizing
- MUST BE STERILE
- inject vol > than that taken -> DISTEND joint
- add 125 mg of amikacin
- allow 5-30 min for effect
true or false: presence of skin sensation does not mean block failed
true; skin first lost and first regained
what’s important to remember about the low 4 point block?
MUST be sterile because you might hit tendon sheath
where is high 4 point block injected?
below carpus in groove between DDFT and suspensory ligament
how many injections for the 4 point block?
1-2
most nerve blocks can be done with a clean prep. which must be sterile?
-low 4 point block: because you might hit the tendon sheath
also intra-articular anesthesia
