Anaesthesia for minor procedures Flashcards
What is an analgesic?
A drug which reduces perception of pain (not an anaesthetic).
What are the components of the anaesthetic triad?
Unconciousness
Analgesia
Muscle relaxation
What percentage of oxygen is required during anaesthesia to prevent hypoxia?
30-40%
What details of the animals are required before administering anaesthesia?
The weight of the animals (shows if they have lost weight after the procedure, not to calculate dosage)
Date they arrived (at least 7, preferrably 14 days)
Strain/genotype
Clinical examination results, health screens, blood samples
What should the flow rate into an anaesthetic chamber be?
10-50ml/min
What are some ways of reducing side effects of anaesthesia in animals?
Combining techniques (using lower doses of both)
Addition of local anaesthetics or analgesics
What must be done to the animal when anaesthesia is complete?
Wait until the animal regains its reflex, and then return it to a warmed incubator/recovery box
What factors need to be monitored during anaesthesia?
Depth of anaesthesia
Respiratory function
Cardiovascular function
Body temperature
How is depth of anaesthesia assessed?
A noxious stimulus may be applied (stimulus that would be painful if the animal were conscious) e.g. pinch between toes and check for pedal withdrawal reflex
May be able to observe blink response
How many breaths per min do rats and mice usually have?
Mice - 200-300 (?)
Rats - 80-100
How can body temperature be measured?
Using an oesophageal temperature probe (use heat pads)
What does a pulse oximeter measure?
Haemoglobin saturation and heart rate
What are the typical heart rates of rats and mice?
Mice - 450-650
Rat - 350-400
How many degrees of heat loss is considered hypothermia in mice, and how quickly can it develop?
Loss of 2-5C within 5-10 minutes
How could you tell if a mouse is lacking oxygen saturation (aside from pulse oximeter)?
They may develop a bluish tinge on the nose and mucus membranes
What does the oxygen saturation rate under anaesthesia need to be?
95-97%
What should you check if respiration rate under anaesthesia is too low?
Check animal’s airway, check that the face mask is connected, reduce the depth of anaesthesia (when using an inhalant agent)
Ventilation can be assisted by blowing down the tube
What are some ways of speeding up recovery from anaesthesia?
Intravenous administration
The use of antagonists
Preventing hypothermia
How long does it take to fully recover from anaesthesia?
24-48 hours or longer
What are some methods of supportive care after anaesthesia?
Use of synthetic bedding, retaining nests that the rodent has made, using heating pads, giving wet food to encourage fluid intake, do not isolate rats after procedures
What are some factors affecting the choice of inhalation anaesthetic agent?
MAC value - measure of the potency of inhalational anaesthetics
Density of the agent
Cost
Speed of onset and recovery
What are the components of anaesthetic machines?
Source of carrier gas - usually oxygen in a cylinder
Pressure regulator - reduce gas from compressed gas cylinders to lower pressure
Flowmeters - to control the gas flow
Vaporisers - produce anaesthetic vapour from liquid anaesthetic
Outlet port - connects to the anaesthetic breathing system
Why does fresh gas flow have to be higher than exhaled gases, and what should the flow rate be?
To make sure all exhaled gases are blown out of the mask and to ensure that when the animal breathes in, only fresh gases from the anaesthetic machine are inhaled.
Flow rate - 3x the estimated minute volume
Is fentanyl: analgesic, sedative and analgesic, or an injectable anaesthetic?
Analgesic
Is isoflurane: analgesic, sedative and analgesic, or an injectable anaesthetic?
Inhalational agent
Is Medetomidine: analgesic, sedative and analgesic, or an injectable anaesthetic?
sedative and analgesic
Is propofol: analgesic, sedative and analgesic, or an injectable anaesthetic?
Injectable anaesthetic
Is alfaxan: analgesic, sedative and analgesic, or an injectable anaesthetic?
Injectable anaesthetic
