PILB Flashcards
What is general anaesthesia?
total unconsciousness, resulting from the administration of drugs that
depress brain function
What is local anaesthesia?
loss of sensation to part of the body, produced by applying drugs which block
nerve conduction
What is regional anaesthesia?
loss of sensation in a region of the body produced by application of local
anaesthetic to the nerves supplying that region; e.g., epidural anaesthesia
What are sedatives?
Relieve anxiety and cause drowsiness
What are tranquillizers?
Relieve anxiety without causing drowsiness. Animals may still be readily roused
What are the advantages of using sedatives or tranquillizers?
Sedatives and tranquillizers potentiate the action of anaesthetics. They are useful in calming the animal
before induction of anaesthesia and in reducing the dose of other drugs required to produce general
anaesthesia. Administration of sedative doses of drugs before the induction of full general anaesthesia is
known as ‘pre-medication’ and is often used in large animals.
What are the advantages of using anaesthetics?
Control the level of pain
What are the disadvantages of using anaesthetics?
Anaesthesia can result in depression of
cardiovascular and respiratory systems and can cause death – the overdose of anaesthetic is a Schedule 1
method for humane killing
What kind of mice should be anaesthetized?
Healthy, stress-free
What preparations should be done before anaesthetics?
Acclimatization: Acclimatise to the environment before anaesthesia to recover from transport stress.
Health status: Ensure the animal is breathing regularly and the mucous membranes are pink. Some animal models may be particularly susceptible to problems under anaesthesia, e.g. neonatal or aged animals and animals with cardiovascular phenotypes.
Pre-anaesthetic fasting: Monogastric animals such as dogs cats and pigs benefit from being fasted before anaesthesia to prevent vomiting on induction. Small animals, such as rodents and rabbits, should not be fasted.
What are examples of opioids?
Morphine, pethidine, fentanyl, buprenorphine, or butorphanol provide analgesia for relief of moderate to severe pain
What are examples of non-steroidal anti-inflammatories?
Carprofen, ketoprofen, flunixin, or meloxicam are effective in the treatment of mild to moderate pain
What are examples of sedatives or tranquillizers?
Benzodiazepines, alpha 2 adrenergic agonists, butyrophenones, phenothiazines, and ketamine
What are examples of anticholinergics?
Atropine and glycopyrrolate may be used in some animals to reduce salivary
secretions
What are the types of local anaesthetics and what examples can be suggested?
Anaesthetics that can be applied topically, e.g. EMLA cream; anaesthetics that can be injected, e.g. lignocaine, bupivacaine; anaesthetics that can be injected to nerve trunk for desensitization over a large area, e.g. epidural or paravertebral block.
What is the role of narcosis?
Loss of consciousness
What is the role of analgesia?
Absence of pain sensation
What is the definition of relaxation?
Loss of muscule tone and reflexes
Why does ‘balanced’ anaesthesia need to be produced?
There is no single agent that alone provides satisfactory narcosis, muscle relaxation and analgesia. Consequently, the best anaesthesia is usually
achieved by combining several agents (including sedatives, analgesics and anaesthetics) to give what is
termed ‘balanced’ anaesthesia.
What are the considerations to choose anaesthetic agents?
- The species and age of the animal
- The duration of the procedure
- The depth of anaesthesia required
- The purpose of the investigation
- The equipment available
- The experience of the staff
What are the two phases of anaesthesia?
- Induction
- Maintenance
What are the administrative ways for anaesthesia?
Injection, inhalation and immersion
What are the pros of injectable anaesthesia?
- No need for complicated equipment
- Simple to administer
- Minimal cost
- Induction with intravenous agents is very rapid
What are the cons of injectable anaesthesia?
- Difficult to adjust the level of anaesthesia
- Easy to overdoes
- Variable length of anaesthesia
- Variable in sex, age and strain
- Agents can be metabolized
What are the benefits of intravenous injection of anaesthetics?
Drugs are administered directly into the circulation and can be titrated to effect.
What are the consequences of intra-peritoneal, intra-muscular and sub-cutaneous injection of anaesthetics?
Drugs are administered as a single dose.
There is a risk of over- or under-dosing, induction and recovery can be slow, a larger total dose is required, and there can be pain on administration. These are used if handling is a problem
What is the equation for calculating the dose to be delivered?
weight of the animal (kg) times the dose required in mg/kg divided by the concentration of the drug in mg/kg
What are examples of injectable agents?
- Ketamine and sedative combinations
- Hypnorm (fentanyl/fluanisone) and sedative combinations
- Propofol
- Alfaxalone
- Urethane, Alpha-chloralose (for terminal anaesthesia only)
What are the advantages of reversal agents for injectable anaesthetics?
- Animals become active more rapidly and will be less at risk of hypothermia. Many anaesthetic drugs depress respiration; this is reversed with antagonist drugs.
- When reversing an opioid such as fentanyl with another opioid (e.g. nalbuphine or buprenorphine), the adverse effects of the fentanyl are reversed. Still, the analgesia persists because of the action of the agonist/antagonist. This is known as sequential analgesia.
What are the pros of inhalable agents?
- Rapid induction and recovery
- Easy to adjust the depth and duration, safer to control
- Minimised metabolism
- Good for rapid procedures
- Good for high-frequency anaesthetics
What are the cons of inhalable agents?
- Bulky equipment
- Disposal of waste gas
- More operative skills required
- Expensive equipment
- Induction is stressful in some species
What equipment is required to administer volatile agents?
- A source of oxygen
- A flowmeter to measure the oxygen flow
- An anaesthetic vaporiser: these deliver a controlled percentage of vapour independent of the flow rate.
- A delivery system from the vaporiser to the animal. There are several types of delivery systems that may be used to achieve this. These include induction chambers, face masks, and endotracheal tubes. Each has its advantages and disadvantages.
- A mechanism to deal with waste gases
What are the effects of anaesthetics and are there any examples?
- Alpha-chloralose: a very prolonged recovery period associated with considerable involuntary excitement
- Urethane: severe peritoneal irritation and carcinogenic
- Chloral hydrate: poorly analgesic
and can cause paralytic ileus following anaesthesia in the rat.
What should be considered after anaesthesia?
- Warmth: Continue to provide heat in the post anaesthetic period until the animal is fully recovered and able to maintain its own temperature.
- Bedding: Ensure the animals are given comfortable, absorbent bedding and cannot push the bedding to one side and end up lying on the cage floor.
- Fluid therapy: Animals may not drink in the post-anaesthetic period and could suffer dehydration. Continue to monitor fluid intake and supplement as required.
- Urine and faecal output: These indicate whether the animal’s physiology returns to normal. Lack of urine may indicate dehydration or pain, and lack of faeces may indicate ileus (gut stasis).
- Feeding: Animals in the post anaesthetic period may not want to move to feed and may not be able to reach the food hopper. They may require a convalescent diet and may need food to be placed within reach on the floor of the cage.
- Monitoring of body weight: This is advised following anaesthesia. Supplements may be required.
- Analgesia: Acute pain can be alleviated by centrally or peripherally acting analgesic drugs administered systemically,
by local anaesthetics, or by applying supporting bandages or other means of protecting and immobilising damaged tissues. The selection of a particular treatment regimen will vary, depending
upon the nature of the pain, its cause, and its estimated severity and duration.
What should be checked during and after anaesthesia?
- AIRWAY - Check the airway is unobstructed
- BREATHING – Switch off the vaporiser (or stop continuous infusions), give 100% oxygen, and assist ventilation– 20-30 breaths/minute.
- CIRCULATION - Give fluids to maintain blood pressure. In larger animals, heart massage may be appropriate.
- DRUGS – Give an anaesthetic antagonist if available (unless surgery is still in progress). Respiratory stimulants can also be used
What health and safety issues should be considered when performing anaesthesia?
- Where volatile anaesthesia is used, there must be adequate scavenging methods to avoid personnel exposure to waste gases. Care should be taken to use pressurised gas cylinders properly.
- Anaesthetic set-ups should be regularly checked and serviced to make sure they are fit for purpose.
- If immersion anaesthesia is used the wastewater should be disposed of in accordance with local rules.
- With injectable agents, needles should not be recapped to avoid accidental self-injection. This can also occur if animals are inadequately restrained and move suddenly. All pre-filled syringes should
be clearly labelled as to their contents.
What are the ranks in the personal license?
Category A – minor procedures with no anaesthesia
Category B – minor procedures with brief anaesthesia (corresponds to PILB training)
Category C – major surgical procedures with recovery anaesthesia or prolonged non-recovery anaesthesia (corresponds to PILC training)
Category D – use of neuromuscular blocking agents
What are the ranks in the project license?
AA: No anaesthesia when the technique is applied
AB (L): Recovery anaesthesia (local)
AB (R): Recover anaesthesia (regional)
AB (G): General anaesthesia with subsequent recovery
AC: General anaesthesia without subsequent recovery
AD: General anaesthesia with the use of neuromuscular blocking agents
