Local anesthetic techniques

Ron Mandsager, DVM, DACVA
4/8/03

Pharmacology

Mechanism of action

Factors affecting onset, intensity, and duration of neural blockade

 Differential blockade of nerve fibers

 Susceptiblity of nerve fibers to local anesthetic block.

 

Anatomic location

Fiber type &
diameter (µm)

Function

Sensitivity to block

 C fibers

Postganglionic sympathetic, sensory roots, and afferent peripheral nerves

non-myelinated

0.4-1.2 µm

Vasomotor, visceromotor, pain, temperature, touch

++++

 B fibers

Preganglionic sympathetic

myelinated

< 3 µm

Vasomotor, visceromotor

++++

 A fibers
 myelinated
A
Sensory roots
1-4 µm
Pain, temperature, Muscle tone,
+++
A
Efferent to muscle spindle
3-6 µm
"
++
A
Efferent and Afferent to muscles and joints
6-22 µm
Motor and proprioception
++

A

 "

"

"

+

 

Toxicity from local anesthetics

 CNS toxicity:

Cardiovascular toxicity:

Epidural injection technique

Brachial plexus block

brachial plexus block

brachial plexus block

Carpal Block

carpal block anatomy

Dental blocks

 LOCAL ANALGESIA TECHNIQUES IN CATTLE

 Outline

CORNUAL NERVE BLOCK

AURICULOPALPEBRAL BLOCK

 

INTRAVENOUS REGIONAL ANALGESIA (IVRA) OF THE DIGIT

 

PROXIMAL PARAVERTEBRAL BLOCK (Farquharson, Hall or Cambridge Technique)

Proximal Paravertebral Block

 

DISTAL PARAVERTEBRAL ANALGESIA (Magda, Cakala, or Cornell technique)

INFILTRATION ANALGESIA

 

INVERTED "7" OR "L" BLOCK

CAUDAL EPIDURAL ANALGESIA

Sacral-coccygeal junction

Location of Sacral-Coccygeal junction for the epidural injection in cattle. Note the tail can be lifted up and down to yield an indentation at the junction.

Caudal epidural
The shaded areas represents the area blocked following a caudal epidural lidocaine injection.  It induces both analgesia and motor blockade.

 

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Last modified October 19, 2007 by Ron Mandsager, DVM, DACVA
Questions? Comments? Contact me at aerrane@okstate.edu
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