Introduction to Anaesthesia and Pre-Anaesthesia Assessment
Description
BVSc3 CVS1 (Clinical Anaesthesia & Analgesia) Mind Map on Introduction to Anaesthesia and Pre-Anaesthesia Assessment, created by Jess Pope on 20/12/2016.
Introduction to
Anaesthesia and
Pre-Anaesthesia
Assessment
Important terms
Anaesthesia
Lack of sensibility to painful stimuli
General anaesthesia
A state of unconsciousness
Produced by anaesthetic agents
Absence of pain over entire body
e.g. isofluorane
Regional Anaesthesia
Insibility due to an interruption
of sensory nerve conduction in
any region of body
e.g. lidocaine
Sedation
Allaying of irritability or
excitement
Anxiolysis
Reduced anxiety
Term used more in human medicine
Analgesia
Reduced sensibility to pain
Narcosis
A sleep like state
Hypnosis
Artificaily induced state of passivilty
Legal issues
Protection of Animals
(Anaesthetics) Act
Anaesthesia mandatory for
"any procedure with or without the use of
instruments which causes interference with the
sensitive tissues or bone structure of an animal"
Exceptions
Emergency first aid
Certain specified procedures
Castration
Tail docking
Farm animals
before certain ages
Misuse of Drugs Act & Misuse
of Drugs Regulations
Classifies drugs
5 schedules of medicinal drugs
1
No relevant veterinary use
e.g. amphetamines
2
Most full agonist opioids
Ketamine
Somilase (equine sedation)
Locked in steel cupboard
Rag bolted to wall
Keys come with cupboard,
can only be cut any
authorised person
Hardbound book
recording purchase and
use
Per individual animal
Can be inspected at any time
Handwritten by vet
Date, time, animal, vet, dose, signature
3
Some partial agonist opioids
e.g. buprenorphine
Midazolam
Tramadol
Storage as for
schedule 2
Records of purchase required
Individual animal use
doesn't need
recording
But RCVS
recommends
that you do
4
Other benzodiazapams
5
Preparations
containing low
doses of codeine
Relevant for
penalties for
possession
Medicines regulations
Classifies veterinary medicines
Licenced anaesthetics are POM-V
Can only be
prescribed by a vet
surgeon
Veterinary Surgeons Act (1966) and
Amendment Order 1982
Annotations:
“18.9 Veterinary nurses and student veterinary nurses may be directed to assist veterinary surgeons with the maintenance of
anaesthesia and the monitoring of patients under anaesthesia. The following advice applies to these tasks:
a. Inducing anaesthesia by administration of a specific
quantity of medicine directed by a veterinary surgeon may be carried out by a veterinary nurse or, with supervision, a student veterinary nurse, but not any other person.
b. Administering medicine incrementally or to effect, to
induce and maintain anaesthesia may be carried out only by a veterinary surgeon.
(IV anaesthetic – need to assess depth of anaesthesia during
induction – must be done by a vet)
c. Maintaining anaesthesia is the responsibility of a veterinary surgeon, but a suitably trained person may assist by acting as the veterinary surgeon’s hands (to provide assistance which does not involve practicing veterinary surgery), for example, by moving dials.
d. Monitoring a patient during anaesthesia and the recovery
period is the responsibility of the veterinary surgeon, but may be carried out on his or her behalf by a suitably trained person.
e. The most suitable person
to assist a veterinary surgeon to monitor and maintain anaesthesia is a veterinary nurse or, under supervision, a student veterinary nurse.”
Defines who is permitted to perform acts of surgery
Nurses may undertake Schedule 3 procedures
Animals (Scientific
Procedures) Act
1986
Allows procedures to be
performed on animals
Licensed individuals working under a
Home Office Project Licence for
scientific reasons
Strict controls on pain and suffering
Health and Safety
Legislation
Many of these are relevant
to anaesthesia
e.g.waste gas scavenging
Drugs and chemicals
(COSHH)
Sharps and clinical waste disposal
Animal handling
Anaesthetic triad
Unconsciousness (unaware
of surroundings)
Reflex suppression
(analgesia)
Not perceiving pain
Reduces response to maxis stimuli
CNS depressed
Analgesia is a more useful term
when animal is unconscious
Muscle relaxation (ease of
performing procedures)
Phases of anaesthesia
Pre-med
Sedative
Opioid
Typically
Induction
Maintenance
Recovery
Risks in different species
Animal factors
Species
Dog/cat will require different
protocol to a horse
Age
Health status
Temperament
Aggressive
c.f. tepid dog
Different levels of sedation
Planned procedure
Invasiveness
Duration
Consideration of
haemorrhage
Drugs and facilities
available
Experience of
the team
Informed owner consent
Discuss risk with owner
Assessment
How to perform it
Liase with owner
Confirm starvation period
Discuss anaesthetic
procedure
Phone numbers
Arrival/collection
times
Consent forms
Discuss use of
unlicensed drugs
Warn about
clipping
Animal details
Brief history
Current medication
Narrow therapeutic dose -
need to know if any other
medications will have an
effect
Vaccination status
Temperament
Physical examination
BCS
Pulse rate and quality
Mucous membranes
Thoracic auscultation
Jugular veins
Location of
IV catheter
in LA
Swelling/abdominal distension
Animal with ascites
Issue with ventilation
Compression of fluid return
Pe-anaesthetic tests
ECG
Radiography
Ultrasonography
Blood tests
Healthy vs sick animals
Will the results change planned
procedure or case management?
Will they influence
anaesthetic protocol?
Can the sample be obtained without
causing the animal stress?
Timescale for results?
Will they come soon enough?
Urinalysis?
Useful for indication of renal function
Often underused
Targeted tests for
individual animal
Arrhythmia - listen for it
Confirm with a test
Influences of breed and species
Cavalier king charles spaniel - mitral valve
regurgitation, so heart murmurs are common
- this has an impact on how we anesthetise
them
Polycystic kidney disease in persian cats -
palpate kidneys and abdomen, also take
bloods to check
Degree of brachycephalic
obstructive syndrome
RTA - damage to thorax and
abdomen - optomise the animal's
condition before pre-med
Fit racehorse c.f.
child's pony
Large cardiopulmonary
reserve
Hard to maintain
anaesthesia
Very low respiratory
rates in anaesthesia
Hard to maintain a
stable platform
Careful induction
required
Doberman
Von willebrand's
disease
Need to check with a
blood sample
Auscultate chest
Dilated
cardiomyopathy is
another risk
Bulldog
Breathing
issues
Brachycephalic obstructive
syndrome will cause issues in
anesthesia
Bad idea to pre-med then
leave in a kennel
Often will pre-med in
an induction area
Danger areas are before induction
and after removing endotracheal
tube in recovery
Would want it to be standing
and walking around before
left to recover
Short legs
Placing an IV
catheter can also
be an issue
Sight Hound
Take longer to recover
from anesthesia
BC - skinny
Predisposed to hypothermia
Metabolise anesthetic drugs
differently to other species
Diff. dosing in large breeds
cf. small breeds
Need to be careful as it will take
them a long time to recover properly
ASA Risk Categories
I
Normal healthy animal
II
Mild systemic disease
e.g. dental disease,
cruciate rupture
III
Systemic disease
Well compensated or
controlled by treatment
e.g. Cavalier King Charles Spaniel heart
murmur but no signs of congestive
failure
IV
Severe uncompensated
systemic disease
e.g. Cavalier King Charles Spaniel
heart murmur with signs of
congestive failure