– Definition:
Anaesthesia means insensibility. It is the name given to the whole art and science relating to the production of insensibility.
It is a reversible process to produce a convenient, safe, effective, yet inexpensive means of chemical restraint so that medical or surgical procedures may be expedited with minimal stress, pain, discomfort, and toxic side effects to the patient or to the anaesthetist.
- Criteria for selection of drugs and techniques of anaesthesia
The choice of the anaesthetic agent or technique depends on several variables:
1) Facilities and anaesthetic equipment available.
2) Personal knowledge and experience.
3) Safety of the anaesthetic agents and cost.
4) The species of animal involved:
a- Size of the animal
b- Demeanor (Temperament).
c- Anatomical and physiological peculiarities.
5) Nature of the operation to be performed:
Magnitude, site and duration of the operation.
6) Physical status of the animal.
Peripheral Anaesthesia
Local and Regional Anaesthesia
Local anesthesia
Local anaesthetics / analgesics
Loss of sensation in a defined body area without loss of consciousness.
These are substances having selective and transient paralytic action on the sensory nerves and nerve endings and are used for inducing both local and regional anaesthesia.
Vasoconstrictor + local anaesthetic
|
Potency ratio |
Uses |
Trade name |
Anaesthetic agent |
|
1:1 |
1-4% |
Novacaine |
1- Procaine Hcl |
|
5:1 |
1-2% |
Pantocaine |
2- Amethocaine Hcl |
|
2:1 |
1-2% 2-4% topically |
Xylocaine |
3- Lignocaine Hcl (Lidocaine) |
|
2.5:1 |
Carbocaine |
4- Mepivacaine |
|
|
8:1 |
0.5-1.0% |
Marcaine |
5- Bupivacaine |
|
20.0 |
0.5% |
Nupercaine |
6- Dibucaine |
· increase duration almost 5 times.
Hyaluronidase + local anaesthetic
· doubles the anaesthetized area.
· Potentiation of local anaesthetics:
Toxic effect of local anaesthetics:
· Drowsiness, twitching and convulsions.
· Respiratory depression, bradycardia and hypotension.