Anaesthetic Techniques, Equipments
Professor & Head
Dept. of Veterinary Surgery & Radiology
College of veterinary science & A. H.
S. K. Nagar
Dr. Hitendra B. Prajapati
M. V. Sc Scholar
Dept. of Veterinary Surgery & Radiology
Dr.V.M.Jhala Clinical Complex,Deesa
• Anaesthesia is used to denote loss of sensetion
to any part or whole of the body, produced by
agents which depress the activity of nervous
tissue either locally or centrally.
• It is revesible process.
Types of anaesthetic techniques:-
A. General anaesthesia:-
B. Local anaesthesia:-
3.regional nerve block
• It is a state of unconsciousness produced by a
process of controlled, reversible, intoxication of
the central nervous system in which there is a
lowered sensibility to stimuli from the
environment and a diminished motor response to
• Intravenous anaesthesia in veterinary practice is
primarily used for the induction of anaesthesia
which is subsequently maintained by ihalation
anaesthesia in small animals.
• Method of administration:-
1. Open insufflation
2. Semi open systems without nonbreathing valves
3. Semi open system with nonbreathing valves
4. Semi closed and closed systems
*Volatile or gaseous
Use of Cone/Mask
Inhalation anaesthetic method,open method
• Anaesthetic sloution is applied topically in the
form of gel, solution or aerosol on the eye and
mucous membrane of penis, vagina, rectum,
urethra etc.(Topical) or injected locally in surgical
• Besides, anaesthetics are injected around a large
nerve trunk(Regional nerve block) or in the
epidural or subarachnoid space(Epidural) Or in
distal to the site of a tourniquet
Common methods of producing
• Surface (topical) anesthesia
• Intrasynovial anesthesia
• Infiltration anesthesia
• Spinal anesthesia
• Intravenous regional local anesthesia
• Regional anesthesia
Surface (topical) anesthesia:-
• This refers to the use of local anesthetics in
solution sprays as well as in various creams
and ointments, on mucous membranes; drops
into the eye; sprays or brush in laryngeal area,
infuse into the nostrils, urethra, or rectum.
• In joints, bursa, and tendon sheaths.
• Useful for both diagnosis of lameness, and for
general pain relief.
• The local anesthetic chosen must cause
minimal irritation, and great care in sterility is
necessary as infection in these sites occurs
• By this method the nerve endings are affected at
the actual site of operation.
• Most minor surgery can be done this way,
excluding surgery on teats in cattle or small
• Never inject local analgesic through infected
• where this is used is on the teats of cattle (do not
use epinephrine here, as vasoconstriction could
lead to ischemic necrosis and sloughing of tissue)
or around the limb of cattle.
• Spinal anesthesia is the injection of local
anesthetic around the spinal cord.
• Spinal anesthesia is divided into two types;
‘epidural’ and ‘true spinal’.
– Epidural (or extradural) anesthesia refers to
depositing of local anesthetics into the extradural
space. The needle enters the spinal canal, but does
not penetrate the meninges.
– True spinal anesthesia refers to the subarachnoid
access (usually known as ‘spinal’ anesthesia) in which
the needle penetrates the dura mater.
Intravenous regional local anesthesia
• In this technique, a limb vein
• Apply tourniquet placed
around the limb, at a pressure
adequate to prevent arterial
circulation (> 150 mmHg).
• Local anesthetic (preferably
without epinephrine) is then
injected into the vein.
• After a period of 15 minutes
the area distal to the
tourniquet is anesthetized
until the tourniquet is
Paravertebral Nerve blocks:-
• It refers to the perineural
injection of local
anesthesia about the
spinal nerves as they
emerge from the vertebral
canal through the
• Its advantage is that it
provides analgesia and
muscle relaxation of the
whole area covered by
the segmental nerves
blocked. T-13, L-1, L-2
Auriculopalpebral Nerve Block:-
• This block can be used to prevent the eyelids
moving during clinical examination or surgery.
• It blocks the orbicularis oculi muscle.
• The nerve course runs from the base of the ear
past the eye ventrally along the facial crest.
– Prevent eyelid closure during examination of the
• Injection site:
– The needle is inserted in front of the base of the
ear at the base of the ear at the end of the
zygomatic arch and is introduced until its point lies
at the dorsal border of the arch.
– This block does not produce analgesia of the eye
or the lids.
– In conjunction with topic analgesia (2% lidocaine)
it is useful for the removal of foreign bodies form
the cornea and conjunctival sac.
Cornual Nerve Block:-
• This block is used for dehorning.
• The nerve can be found at the orbit running
behind the lateral ridge of the frontal bone.
• The nerve supplies the horn coruim and the
skin around the base of the horn.
Mandibulo-Alveolar Nerve Block:-
• It is used to desensitize the lower jaw
alongwith its teeth and lower lip.
• Management of surgical condition of molar
teeth and incisors and the body of the
mandible,suturing of wound of the teeth.
Mental Nerve Block:-
• To desensitize the dental nerves of the lower
jaw in the mandibular canal and at the mental
• Suturing of wound of lower lip, wiring
operations around the lower teeth and the body
of the mandible.
Infra-Orbital Nerve Block:-
• To desensitize the whole anterior half of the
face including the cheek teeth as far as the
second molar, nostril,upper lip, gum and
• Surgical management of conditions of upper
lip and nostril.
Maxillary Nerve Block:-
• For surgical management of the conditions of
the upper lip, nose and upper jaw
• The maxillary nerve is blocked in the
pterygopalatine fossa before it enter the infra
Retrobulbar Nerve Block:-
• For the surgical management of conditions of
eyeball and membrana nictitans
• The needle is inserted through the lateral
canthus of the eye
• Electronarcosis:-anaesthesia is achieved by
passing an electric current through theccerebrum
to induce deep nacosis although the method is
rarely used in veterinary practice.
• Acupuncture:-an ancient Chinese system that
involves insertion of specially designed needles at
specific points and their stimulation by various
means to produce analgesia.
• Hypothermia:-the procedure involves decreasing
the body temperature either locally or generally to
minimize the anaesthetic doses.
Endotracheal Tubes (ET Tubes)
Flexible tube placed in the trachea
Delivers anesthetic gases directly from the
anesthetic machine to the lungs
Less anatomical dead space
Precision administration of anesthetic agent
Prevents pulmonary aspiration
Responds to respiratory emergencies
Types of Endotracheal Tubes
Murphy tubes (A, C,D)
Beveled end and side holes
• D. Red rubber
Cole tubes (B)
No side hole or cuff
Abrupt decrease in diameter of the tube
Used in birds and reptiles
Parts of the Endotracheal Tube
Patient end (i)
Machine end (c )
Connector ( D)
Cuff ( H)
Pilot balloon (b)
and valve (a)
Murphy Eye- J
Used to increase the visibility of the larynx while
placing an ET tube
Handle containing batteries
Blade to depress tongue and epiglottis
Light source to illuminate the throat
Small animal 0 to 5; large animal up to 18-inch blade
Miller blades A, C, E
McIntosh blades B, D, F
Cone-shaped devices used to administer oxygen
and anesthetic gases to nonintubated patients
Used for induction and maintenance of anesthesia
in very small animals
Plastic or rubber
Variety of diameters and lengths
Clear, aquarium-like boxes used to induce general
Used in feral, vicious, or intractable animals to
Acrylic or Perspex
Removable top with two ports
Cannot monitor patient closely
Used to deliver precise amounts of oxygen and volatile
anesthetic under controlled conditions
Principles of Operation of
Carrier gas: oxygen or nitrous oxide
Liquid inhalant anesthetic: to be vaporized
Mixed gases delivered to patient
Exhaled gases removed from patient: scavenging
system or recirculated
Components of the Anesthetic Machine
Compressed gas supply
(precision or nonprecision;
VOC or VIC)
Breathing circuit (rebreathing
Compressed Gas Supply
Used to increase inspired air to at least
Level necessary to maintain cellular
metabolism under anesthesia
Used to carry vaporized anesthetic to
Contain large volume of gas under high
E tanks (small), attached directly to
H tanks (large), attached remotely to
Compressed Gas Supply (Cont’d)
Control valve (outlet port)
Located on top of the tank
Left loose (open), right tight (closed)
Pressure-reducing valve (B)
Reduces outgoing pressure to a usable level
Tank pressure gauge C
Line pressure gauge D
Used on all but very small animals
Carbon dioxide removed from exhaled air
Exhaled air is inhaled again with added oxygen
Rebreathing System (Cont’d)
Closed rebreathing system
Pop-off valve is nearly or completely closed and
oxygen flow is low
Used mostly in large animal anesthesia
Semiclosed rebreathing system
Pop-off valve is open and oxygen flow is high
Excess air is released into scavenging system
Most common configuration
Breathing Tubes and Y-Piece
Corrugated breathing tubes or inspiratory and
expiratory breathing tubes
Carry anesthetic gases to and from the patient
Connected to unidirectional valve and Y-piece
Three sizes: 50 mm, 22 mm, and 15 mm in
Connects breathing tubes
Connects to mask or endotracheal tube
Used in very small patients (<2.5 kg)
Little exhaled gas is returned to the patient
Exhaled gas is evacuated by the scavenging system
Fresh gas is routed to the patient directly from the
No carbon dioxide absorber canister, pressure
manometer, or unidirectional valves
Several configurations are available
Components: Endotracheal tube connector, fresh gas
inlet, reservoir bag, overflow valve, scavenger tube, and
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