Anaesthesia - PowerPoint PPT Presentation

1 / 36
About This Presentation
Title:

Anaesthesia

Description:

'Balanced anaesthesia' Eg ketamine: if used alone, poor muscle relaxation ... 'Laboratory Animal Anaesthesia' - vital reading. Which agents are you likely to be using ... – PowerPoint PPT presentation

Number of Views:213
Avg rating:3.0/5.0
Slides: 37
Provided by: belindaf
Category:

less

Transcript and Presenter's Notes

Title: Anaesthesia


1
Anaesthesia
  • Belinda Farnfield

2
Some definitions and terms
3
Anaesthesia Analgesia
  • Anaesthesia
  • State of controllable, reversible insensibility
  • general - loss of consciousness
  • local - loss of sensory and motor function
    confined to a specific region
  • Analgesia
  • Temporary abolition or diminution of pain
    perception

4
Sedatives Tranquillisers
  • Sedatives
  • Drowsiness
  • Reduced fear apprehension
  • Tranquillisers
  • Calming effect
  • No sedation
  • Overlap, species variation
  • Think of them as one group

5
Muscle relaxants
  • Muscle relaxant
  • Many drugs used as part of an anaesthetic regimen
    produce varying degrees of muscle relaxation
  • Specific term muscle relaxant refers to
  • neuromuscular blocking agent
  • produce paralysis of skeletal muscles

6
Premedication
  • Historical
  • drugs given before anaesthesia to reduce side
    effects
  • eg excess secretions, ether anaesthesia
  • Modern
  • pre-emptive analgesia
  • before painful stimulus occurs
  • sedate/ tranquillise (in larger species)

7
Understanding anaesthetic regimens
8
An anaesthetic regimen includes
  • Induction
  • Maintenance
  • Recovery

9
Induction
  • Refers to general anaesthesia
  • Animal loses consciousness
  • Should be
  • Calm, stress free (and so humane)
  • Safe for animal and handler

10
Maintenance
  • Keeping animal asleep
  • The animal should be
  • Unable to perceive painful stimuli
  • Relaxed muscles
  • Asleep (or immobile)
  • This is called the anaesthesia triad

11
Recovery
  • Rapid return to normal physiology behaviour
  • Abnormal physiology leads to poor animal model

12
Anaesthetics may be given by various routes
  • Possible routes are
  • Inhalation
  • Injection
  • Local
  • Routes may be combined
  • Injectable agent for induction
  • Then inhalational anaesthesia for maintenance

13
Inhalational anaesthesia
14
Inhalational anaesthesia principles
  • Animal breathes in anaesthetic vapour delivered
    in a carrier gas (oxygen /- nitrous oxide)
  • Crosses from alveoli to blood stream
  • Reaches CNS and has anaesthetic effect
  • Side effects
  • Recovery process
  • animal breathes off anaesthetic vapour
  • minimal metabolism

15
Practicalities
  • Two main agents used
  • Isoflurane
  • Halothane
  • Both are liquids at room temperature, placed in a
    vaporiser
  • Oxygen passed through the vaporiser
  • Vapour delivered in oxygen to the animal

16
Equipment used can be complex
17
Induction chambers
  • Induction chambers
  • Useful for small species
  • Minimal restraint needed

18
Face masks
  • Facemasks
  • Need close restraint
  • Or
  • Induction chamber first
  • Or
  • Injectable agents first

19
The anaesthetic machine
  • Take some time with this
  • Well before you are first due to use the machine

20
The anaesthetic machine
  • Find the oxygen cylinder
  • learn to change cylinder, ask about alarms
  • Find the vaporiser
  • learn how to fill it
  • Learn where to connect a breathing system/
    chamber
  • Learn how to connect up and use scavenging
    equipment

21
  • Oxygen cylinder
  • Vaporiser
  • Breathing system/ chamber
  • Scavenging equipment

22
Other equipment you may see/ use
  • Endotracheal tubes
  • Protect and maintain airway
  • Can control ventilation
  • Essential for some species
  • Skill needed to place

23
Isoflurane in the mouse
  • Video isoflurane in the mouse (6 minutes)

24
Injectable anaesthesia
25
Injectable anaesthesia principles
  • Drug is administered
  • Absorption and circulation
  • depending on route
  • Anaesthetic effect once it reaches the central
    nervous system (CNS)
  • Recovery process
  • Metabolism (liver) excretion of drug (kidneys)

26
Practicalities
  • Routes of injection
  • Intraperitoneal
  • Intramuscular
  • Intravenous

27
Many agents and combinations
28
And
  • Lots of dose tables and Recipes
  • Species differences
  • Strain differences

29
Why are combinations of agents used?
  • One agent can be used to produce induction and
    all 3 desired effects of the triad (unable to
    perceive painful stimuli, relaxed muscles,
    asleep)
  • Eg isoflurane
  • Injectable agents are often used in combination
  • Balanced anaesthesia
  • Eg ketamine if used alone, poor muscle
    relaxation
  • Add xylazine improved analgesia and muscle
    relaxation

30
Information overload?
  • Invest some time
  • Get to know the basic drug families
  • plus key examples of each
  • Laboratory Animal Anaesthesia - vital reading
  • Which agents are you likely to be using
  • In which species
  • Get familiar with one protocol at a time

31
One common combination is xylazine and ketamine
  • Video mouse xylazine and ketamine (5 minutes)

32
Selecting a regimen
33
Selecting a regimen
  • May be done for you
  • Join another research group
  • Evaluate question
  • Based on a publication
  • Essential to contact the authors if you are
    adapting something reported in a journal

34
Species procedure
  • Species, strain, age, sex, weight
  • Procedure
  • Depth duration
  • Experience/ skill
  • Equipment available
  • Legal permission

35
During all parts of the regimen
  • A minimum of side effects
  • Normal physiology maintained
  • All body systems
  • This is impossible
  • Desirable effects and side effects must be
    balanced

36
Make a list
  • Which routes are practical?
  • Make a list of possible agents/ combinations
  • Likely interactions with your procedure?
  • Cross off undesired agents
  • Now have one or two left
  • Recovery time
  • Familiarity
  • Cost
Write a Comment
User Comments (0)
About PowerShow.com