Regional Anesthesia Flashcards
Nocieption has what 2 systemic effects?
- Sympathetic stimulation - catecholamines —> incr HR and BP
- Stress response - ACTH incr —> cortisol and BG
What are reasons to provide regional anesthesia?
- Pre-emotive analgesia: reduction of anesthetic drugs
- Reduction of intraoperative complications
- better intra/postoperative pain control
- Faster return to normal activities
- prevents stress response
- Better immune system activity
What are the target structures for topical/surface anesthesia and what are some instances you might use it?
Target structures = free nerve endings, nociceptors
- Uses:
- larynx: avoid laryngospasm
- splash block: reduce postoperative pain
- corneal: proparacaine drops for eye exam
- skin desensitization: EMLA cream - venipuncture/small mass removal (1 cm deep)
Describe local infiltration method and list some of its uses
injection of local anesthetic solution into and around the planned surgical field; does NOT target a specific nerve
Uses:
- resection of cutaneous/superficial mass
- surgical closure of lacerations
- procedures involving an appendage
Name some specific examples of local infiltration
- Line block; infiltrate the SQ and underlying tissues
- Intratesticular block; only for castration
- Ring block; extremity, distal limbs, tail, horn (dehorning)
Where should you make sure to NEVER use lidocaine with epinephrine?
Where there is no collateral circulation; I.e. tail, horn
Where are epidurals most commonly performed in small animals?
The lumbosacral space
The epidural space is between what two anatomical structures?
The interarcuate (flavum) ligament and the dura mater
What are your landmarks for performing an LS epidural on a small animal?
- Iliac crest
- medial sacral crest
- spinous process of L7
When performing an epidural, what is the order of the structures pierced by the needle?
- Skin
- Supraspinous ligament
- Interspinous ligament
- Interacuate ligament (roof of epidural space)
What things are included in an epidural kit?
A Tuohy needle, a loss of resistance syringe, and an epidural catheter
Describe the hanging drop technique
- Advance the Tuohy needle until the interarcuate ligament is perceived
- Removed the stylet and fill the hub of the needle with saline
- When the needle enters the epidural space, the drop should be aspirated
False negatives can occur
Describe the loss of resistance technique
- Advance the Tuohy needle until the interarcuate ligament is perceived
- Remove the stylet and attach the syringe to the hub
- Apply small pressure to the plunger and advance the needle thru the interarcuate ligament
- The resistance to the injection of air suddenly drops when needle enters the epidural space
How do epidurals using local anesthetics vs. opioids differ?
- LA epidurals cause motor AND sensory blockade
- autonomic block causes vasodilation
- Opioid epidurals cause analgesia WITHOUT motor blockade
What are the 2 most common local anesthetics used to perform epidurals?
- Lidocaine: fast onset, short duration (<90 min)
- Bupivicaine: slow onset, long duration (up to 6-8h)
- Low concentration bupivicaine: shorter motor block but preserves sensory block