Introduction to Anaesthesia and Pre-Anaesthesia Assessment

1. Lack of sensibility to painful stimuli

1. A state of unconsciousness
2. Produced by anaesthetic agents
3. Absence of pain over entire body
4. e.g. isofluorane

1. Insibility due to an interruption of sensory nerve conduction in any region of body
2. e.g. lidocaine

1. Allaying of irritability or excitement

1. Reduced anxiety
2. Term used more in human medicine

1. Reduced sensibility to pain

1. A sleep like state

1. Artificaily induced state of passivilty

1. Anaesthesia mandatory for
   1. "any procedure with or without the use of instruments which causes interference with the sensitive tissues or bone structure of an animal"
2. Exceptions
   1. Emergency first aid
   2. Certain specified procedures
      1. Castration
      2. Tail docking
      3. Farm animals before certain ages

1. Classifies drugs
   1. 5 schedules of medicinal drugs
      1. 1
         1. No relevant veterinary use
         2. e.g. amphetamines
      2. 2
         1. Most full agonist opioids
         2. Ketamine
         3. Somilase (equine sedation)
         4. Locked in steel cupboard
            1. Rag bolted to wall
               1. Keys come with cupboard, can only be cut any authorised person
         5. Hardbound book recording purchase and use
            1. Per individual animal
            2. Can be inspected at any time
            3. Handwritten by vet
            4. Date, time, animal, vet, dose, signature
      3. 3
         1. Some partial agonist opioids
            1. e.g. buprenorphine
         2. Midazolam
         3. Tramadol
         4. Storage as for schedule 2
         5. Records of purchase required
         6. Individual animal use doesn't need recording
            1. But RCVS recommends that you do
      4. 4
         1. Other benzodiazapams
      5. 5
         1. Preparations containing low doses of codeine
2. Relevant for penalties for possession

1. Classifies veterinary medicines
2. Licenced anaesthetics are POM-V
   1. Can only be prescribed by a vet surgeon

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.”  

1. Defines who is permitted to perform acts of surgery
2. Nurses may undertake Schedule 3 procedures

1. Allows procedures to be performed on animals
2. Licensed individuals working under a Home Office Project Licence for scientific reasons
3. Strict controls on pain and suffering

1. Many of these are relevant to anaesthesia
2. e.g.waste gas scavenging
3. Drugs and chemicals (COSHH)
4. Sharps and clinical waste disposal
5. Animal handling

1. Not perceiving pain
2. Reduces response to maxis stimuli
3. CNS depressed
4. Analgesia is a more useful term when animal is unconscious

1. Pre-med
   1. Sedative
   2. Opioid
   3. Typically
2. Induction
3. Maintenance
4. Recovery

1. Species
   1. Dog/cat will require different protocol to a horse
2. Age
3. Health status
4. Temperament
   1. Aggressive c.f. tepid dog
      1. Different levels of sedation

1. Invasiveness
2. Duration
3. Consideration of haemorrhage

1. Discuss risk with owner

1. Liase with owner
   1. Confirm starvation period
   2. Discuss anaesthetic procedure
   3. Phone numbers
   4. Arrival/collection times
   5. Consent forms
   6. Discuss use of unlicensed drugs
   7. Warn about clipping
2. Animal details
3. Brief history
4. Current medication
   1. Narrow therapeutic dose - need to know if any other medications will have an effect
5. Vaccination status
6. Temperament
7. Physical examination
   1. BCS
   2. Pulse rate and quality
   3. Mucous membranes
   4. Thoracic auscultation
   5. Jugular veins
      1. Location of IV catheter in LA
   6. Swelling/abdominal distension
      1. Animal with ascites
         1. Issue with ventilation
         2. Compression of fluid return
8. Pe-anaesthetic tests
   1. ECG
   2. Radiography
   3. Ultrasonography
   4. Blood tests
      1. Healthy vs sick animals
      2. Will the results change planned procedure or case management?
      3. Will they influence anaesthetic protocol?
      4. Can the sample be obtained without causing the animal stress?
      5. Timescale for results?
         1. Will they come soon enough?
      6. Urinalysis?
         1. Useful for indication of renal function
         2. Often underused
   5. Targeted tests for individual animal
   6. Arrhythmia - listen for it
      1. Confirm with a test

1. Cavalier king charles spaniel - mitral valve regurgitation, so heart murmurs are common - this has an impact on how we anesthetise them
2. Polycystic kidney disease in persian cats - palpate kidneys and abdomen, also take bloods to check
3. Degree of brachycephalic obstructive syndrome
4. RTA - damage to thorax and abdomen - optomise the animal's condition before pre-med
5. Fit racehorse c.f. child's pony
   1. Large cardiopulmonary reserve
      1. Hard to maintain anaesthesia
   2. Very low respiratory rates in anaesthesia
      1. Hard to maintain a stable platform
   3. Careful induction required
6. Doberman
   1. Von willebrand's disease
      1. Need to check with a blood sample
   2. Auscultate chest
      1. Dilated cardiomyopathy is another risk
7. Bulldog
   1. Breathing issues
      1. Brachycephalic obstructive syndrome will cause issues in anesthesia
   2. Bad idea to pre-med then leave in a kennel
      1. Often will pre-med in an induction area
   3. Danger areas are before induction and after removing endotracheal tube in recovery
   4. Would want it to be standing and walking around before left to recover
   5. Short legs
      1. Placing an IV catheter can also be an issue
8. Sight Hound
   1. Take longer to recover from anesthesia
   2. BC - skinny
      1. Predisposed to hypothermia
   3. Metabolise anesthetic drugs differently to other species
   4. Diff. dosing in large breeds cf. small breeds
      1. Need to be careful as it will take them a long time to recover properly

1. I
   1. Normal healthy animal
2. II
   1. Mild systemic disease
   2. e.g. dental disease, cruciate rupture
3. III
   1. Systemic disease
   2. Well compensated or controlled by treatment
   3. e.g. Cavalier King Charles Spaniel heart murmur but no signs of congestive failure
4. IV
   1. Severe uncompensated systemic disease
   2. e.g. Cavalier King Charles Spaniel heart murmur with signs of congestive failure
5. V
   1. Unlikely to survive 24 hours
6. Can we improve status pre-anaesthesia?