To induce anaesthesia means to:
induce unconsciousness
Anaesthesia may be induced and maintained by either ….. or ….. agents
injectable or inhalational agents
Common induction drugs:
Propofol
- usually given by a bolus and causes rapid induction which allows a short period to intubate.
- Transient apnoea may occur so respiration must be monitored during induction and intubation should occur in a short period to maintain airway.
Common induction drugs:
Thiopentone
- distributed through the body fat
- must be given IV
- should not be given in animals exhibiting shock, anaemia, hepatic or renal damage.
Common induction drugs:
Alfaxalone
- steroid anaesthetic that can be given IV in dogs and cats & deep IM in cats.
- must be given as a slow IV injection, to effect, never as a bolus.
- Alfaxan is also suitable for TIVA (total IV venous anaesthesia)
- Recovery is usually within 60- 80 minutes.
Explain the process of intubation
- select correct ET tube, apply lube
- use a long peice of bandage or drip tubing placed under the front teeth, support the upper arcade of the animals jaw. Ensure the neck is extended while straight to allow good visualisation
- Felines must now have topical local anaesthetic sprayed on the larynx to prevent laryngeal spasms
- Gently pull tongue out and down, enure that the blade of the laryngoscope does not touch the epiglottis, but just sits on the base of the tongue in front of the larynx.
- Insert the ET tube gently past the vocal folds into trachea.
- Check proper placement by checking for patients breath as it exits the ET tube during exhalation
- Once correct, tube should be tied in place. Cuff should be inflated gently and the patient placed on the oxygen. Carefully listen for any leaks around the tube
Should you disconnect the ET tube when moving a patients postition?
YES!!!
Is Isoflurane always delivered with oxygen?
YES
Reflexes to check for level of anaesthesia?
- Palpebral reflex (blinking)
- Pupillary light reflex -pupils constrict to light
- Nystagmus -eye flicking
- Pedal reflex -pinching toes causes w/drawal of leg
- Ear flick
- Jaw tone
- Pharyngeal (swallowing)
- Laryngeal (coughing)
- Anal tone
- Visceral -touching an organ increases resp. effort
- Corneal -touch cornea and animal blinks, last to disappear before death
Levels of Anaesthesia:
Stage 1
Describe
- Voluntary Excitement
- begins with the induction of anaesthesia.
- Animals are conscious and may display “fear, fight, flight” reactions.
- These may be modified with pre-anaesthetic agents
Levels of Anaesthesia:
Stage 2
Describe
- Involuntary Excitement
- begins with the onset of unconsciousness and lasts until rhythmic breathing is established.
- There is reflex struggling and there may be loss of bladder and bowel control.
Levels of Anaesthesia:
Stage 3
Describe
- Surgical Anaesthesia
- This stage is sub-divided into four “planes”
- Plane 1: Light Surgical
- Plane 2: Medium surgical
- Plane 3: Deep Surgical
- Plane 4: Excessively Deep Surgical
Levels of Anaesthesia:
Stage 3: Surgical
Describe plane 1
- light surgical
- Intubation is possible
- Minor examinations and surgical procedures are possible.
- Pupil is located centrally
- Palpebral and corneal reflexes are present
- Withdrawal reflex is present
- Laryngeal and pharyngeal reflexes are present
- Jaw tone is strong
- Respiration is variable
Levels of Anaesthesia:
Stage 3: Surgical
Describe plane 2
- Medium surgical
- Suitable for most procedures
- Pupil is rolled downwards
- Palpebral reflex disappears
- Withdrawal reflex is absent
- Laryngeal and pharyngeal reflexes are absent
- Jaw tone is relaxed
- Heart and respiratory rate are steady
- Painful stimuli increase the heart and respiratory rate
- Corneal reflex present
Levels of Anaesthesia:
Stage 3: Surgical
Describe plane 3
- Deep surgical
- This depth is not necessary for most surgical procedures except where profound muscle relaxation is required
- Pupil is centrally fixed
- Palpebral reflex is absent
- Jaw tone is minimal
- Painful stimulus does not affect heart or respiratory rate
- Corneal reflex is barely present
Levels of Anaesthesia:
Stage 3: Surgical
Describe plane 4
- Excessively Deep Surgical
- This stage is characterised by severe cardiovascular and respiratory depression
- Pupil is located centrally and is dilated
- All reflexes are absent
Levels of Anaesthesia:
Stage 4
Describe
- Death
- Reflexes are absent, respiratory and cardiac arrest.
How does deep levels of anaesthesia impair cardiac and respiratory function?
- tissue perfusion and oxygenation can become impaired leading to tissue damage and cell death.
- Respiratory rate and pulse rates on their own do not reflect the adequacy of the function of the lungs or the heart.
What vital signs should be measured during anaesthesia?
- Pulse and heart rate (note also the rhythm and strength of pulse)
- Mucous membrane colour
- Capillary refill time
- Respiratory rate/effort/sounds
- Tidal volume
- Temperature
How often should anaesthesia monitoring records be updated?
every 5 mins
What is an oesophageal stethoscope used for?
to continuously monitor the heart and respiratory sounds.
The signal may be listened to via the earpieces or transmitted through a speaker
What is an ap-alert respiratory monitor used for?
device sounds and alarm if a patient suffers apnoea (i.e. has not taken a breath after a specified time).
A beeping sound is usually emitted with each breath.
The disadvantage with this device is that no information is given on the adequacy of each breath
What is a pulse oximeter used for?
- measures the pulse rate and the degree of oxygen saturation of arterial blood, by measuring the absorbency of particular wavelengths of red and infer-red light.
- Most instruments require a probe placed on non-pigmented skin
What should be included on an anaesthetic record?
- Animal and procedure details
- Baseline vital signs (i.e. before anaesthesia)
- Drugs given before, during and in the immediate recovery period-drug name, dose and time given
- Anaesthetic regime or equipment used (e.g. endotracheal tube size, rates of administration of anaesthetic gases and vapours, type of anaesthetic machine)
- Vital signs recorded at five minute intervals
- Any relevant comments
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T1: Admissions and Scheduling18
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T2: Premeds30
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T3: Setting Up the Theatre and Anaesthetic Machine24
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T3: Other Equipment13
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T4: Scrubbing In22
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T5: Getting the Patient Ready for Theatre31
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T5: Induction24
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T6: Assisting During Surgery23
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T6: Teaching and Research Facilities0
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T7: Instrumentation and Care23
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T7: Cleaning and Sterilising22
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T8: Common Surgeries7
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T9: Post Operative Care30
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T10: Emergencies6
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T11: Veterinary Dental Nursing46
