Regional anesthetic techniques Flashcards
Features of amino amide structure & examples:
hepatic metabolism (slower), but toxic accumulation is more likely
ex. lidocaine, bupivacaine, mepivacaine
MOA local anesthetics?
block sodium channel
Local anesthetics are considered weak bases? T/F
True, ( becomes ionized in acidic pH causing ion trapping)
- reason should not inject lidocaine into infected tissues which are considered acidic/ so LA does not work
Which local anesthetic has a short onset & short duration?
Lidocaine: fast onset & 1-2 hr duration–> max dose: 5 mg/kg
What fiber types are more susceptible to local anesthetic?
smaller nerve & myelinated fibers
Local anesthetic toxicity is associated with…
high dose, IV injection & reduced biotransformation/ elimination (liver or renal)
What CNS signs are associated with local anesthetic toxicity?
depression of cortical inhibitory pathways, impaired vision, seizures, CNS depression/coma
What CV signs are associated with local anesthetic toxicity?
bradycardia, changes to ECG, VPC, reduced myocardial contractility & cardiac arrest
Topical anesthesia- block indications
superficial mucosal tissue
Topical anesthesia- what nerves are blocked?
free nerve endings & nociceptors
Local infiltration- block indications
skin & underlying tissue
Local infiltration- nerves blocked
free nerve ending, nociceptors & terminal nerve branches (does not target specific nerve)
What do intraneural injections produce?
Nerve damage
Infraorbital nerve block contraindication
risk of ocular puncture in cats & brachycephalic animals!
Maxillary nerve block:
o Nerves blocked: maxillary
o Use: dental; unilateral mandible
o Area desensitization: maxilla (+teeth), paranasal sinus & sinus cavity
Inferior alveolar (mandibular) nerve block:
o Nerves blocked: mandibular nerve (branch of trigeminal)
o Use: dental; mandibular teeth extraction
o Area desensitization: mandible, mandibular teeth & ipsilateral lower lip
Inferior alveolar (mandibular) block adverse effect?
desensitize lingual nerve leading to self mutilation of the tongue during recovery
Why would you select lumbar paravetebral block over inverted L technique?
no LA at margins of surgical site & provides better analgesia than an inverted l technique
What nerves are being blocked with the lumbar paravertebral block?
T13-L1 &L2
Where is the epidural space?
located between interarcutae ligament & duramater
What epidural space is commonly used in SA?
o Lumbo-sacral space is used in small animal (less risk of piercing spinal cord- since it ends at L6-L7)
What epidural space is commonly used in LA?
o Sacro-coccygeal space because spinal cord ends at S1
Landmark for epidural injection- SA?
o Iliac crest, medial sacral crest & spinous process L7
Why is it important to know whether you are epidural or spinal injection?
They need different volumes of LA; which spinal injection requires much lower dose than epidural space!
