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BACKGROUND
Local anaesthesia is a technique to create loss of sensation in specific region of the body.1 Usually they are used in minor surgeries, dental procedures, cesarean section with reduced pain and distress. This technique is safer and superior to general anaesthesia.2
Local anaesthetic drugs produce reversible effect and a loss of nociception. When these drugs are used on specific nerve pathways they show effects such as analgesia and paralysis. Local anaesthetics differ in their pharmacological properties and are used in various techniques such as surface (topical) anaesthesia, infiltration, epidural block, plexus block and spinal anaesthesia.2
The aim of the present study is to determine the activity and tolerability of new local anaesthetics after epidural injection in rabbits.
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REQUIREMENTS
Animals required:
Adult rabbits weighing 2.5-3 kg
Drugs:
Lignocaine 2%, test drug (0.05% and 0.1%).
Instruments used:
1 ml syringe (20 guage needle)
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PROCEDURE
Handle the selected rabbit carefully. Place the thumb and the middle finger of the left hand on the two crests and palpitate the midline, L7 spine and the depression of lumbosacral fossa with left index finger. Introduce 1.5 cm of 20 guage needle at the short bevel at right angles to the skin with the bevel aligned longitudinally. After passage through the skin, only minor resistance was felt until ligamentum flavum was reached. After passing through that, we will experience a pop and we will loss the advancement to the needle. Then withdraw the stylet and check for presence of blood or CSF. If there is no presence of both, then rotate the needle to 90oc to the bevel caudally and 1.0 ml of syringe was attached and inject 0.1 ml of air. Then inject 1.5 ml dose of anaesthetic (standard/test) over 1 period of 5-10 seconds.
Assess the response of the drugs by the sensory and motor blocks (loss of weight bearing ability and flaccid paralysis).
OBSERVATION
|
Drug |
onset of sensory block (in min) |
duration of sensory block (in min) |
onset of motor block (in min) |
duration of motor block (in min) |
|
Lignocaine (2%) |
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|
Test drug (0.05%) |
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|
Test drug (0.1%) |
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CONCLUSION
Mean time taken for onset of block and duration of block are calculated for standard and test drugs. The result determines the activity of anaesthetic.
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REFERENCES
- William A, Catterall A, Kenneth M. Local Anesthetics. In: Laurence Bruton L,Goodman and Gilmans The Pharmacological Basis of Therapeutics, 12 th ed. New Delhi: Mc Graw Hill Medical; 2011: 564.
- Local anesthesia. Available at: https://en.wikipedia.org/wiki/Local_anesthesia. Accessed on 17 October 2017.
- Vogel GH. Epidural anaesthesia in rabbits. Drug Discovery and evaluation-Pharmacological assays. 2nd edition. Newyork: Springer-Verlag; 2003: 658.
