Preparation for anaesthesia

Question 1

Definition of general anaesthesia

Answer 1

An induced, controlled state of unconsciousness accompanied by partial or complete loss of sensation as well as protective reflexes, including the ability to independently maintain an airway and respond purposefully to physical stimulation or verbal command.

Question 2

Main components of general anaesthesia

Answer 2

Unconciousness

Myorelaxation

Immobility

Antinociception/analgesia

Question 3

Other features of general anaesthesia

Answer 3

Transient loss of memory

Loss of protective reflexes (e.g. coughing, swallowing)

Inability to ventilate adequately

Potential cardiovascular depression

Impaired thermoregulation

Question 4

Phases of anaesthesia

Answer 4

Premedication/sedation

Induction of GA

Maintenance of a state of GA

Recovery from anaesthesia

Question 5

Premedication/sedation

Answer 5

Tranquilisers, sedative agents, and analgesics (acepromazine, a2-adrenoreceptor agonists, opioids).

To tranquillise the animal prior to GA, to allow IV catheterisation.

Question 6

Induction of GA

Answer 6

Injectable anaesthetic agents (Propofol, Alfaxalone).

Induction of a state of GA (unconsciousness and loss of reflexes) through injection.

Question 7

Maintenance of a state of GA

Answer 7

Inhalational anaesthetic agents (Isoflurane, Sevoflurane).

Maintenance of patent airways and ventilatory support, monitor physiological variables, CV support if needed.

Question 8

Recovery from anaesthesia

Answer 8

Tranquilisers in horses, analgesics if it applies (a2-adrenoreceptor agonists, opioids, NSAIDs).

Provision of supportive care and analgesia if applicable, monitoring of physiological parameters until they normalise, risk of peri-anaesthetic death extends to the recovery phase.

Question 9

Why is planning an anaesthetic important?

Answer 9

Legal protection of the hospital and its personnel

Patient safety

Improved outcome of the anaesthetic

Improved patient flow and effectiveness within the hospital

Question 10

Legal aspects of anaesthesia

Answer 10

The administration of an anaesthetic drug to effect is an Act of Veterinary Surgery

Knowledge of licensed anaesthetic drugs for specific species and responsible use of cascade

Personnel safety (large animal anaesthesia)

Question 11

Responsibilities of the anaesthetist

Answer 11

Double check that there is owner consent for GA and for planned clinical procedures

Confirm the animal identity prior to performing any procedure

Minimise the risk of contamination, cross infection and accumulation of pathogens

Question 12

Things an owner must consent for anaesthesia

Answer 12

The owner gave consent for GA

Gave consent for that specific clinical procedure

Agrees on estimated costs

Question 13

Anaesthesia basic request form details

Answer 13

Date, time, estimated duration of GA

List of planned clinical procedures

Basic patient details

Etc.

Question 14

Patient details that should be checked before administration of anaesthesia

Answer 14

Species

Breed

age

Pre-placed IV catheter

Obesity, limb oedema, previous venepunctures

Consent for CPCR

Temperament

Fasting time

Question 15

Relevant patient clinical history before anaesthesia

Answer 15

Clinical status

Underlying diseases: increased risk

Current therapies/ medications

Question 16

Clinical exam necessities before anaesthesia (even in emergency)

Answer 16

Thoracic auscultation

Mucous membranes colour, moisture, capillary refill

Pulse quality

Temperature

Question 17

Is routine pre-anaesthesia screening bloodwork necessary?

Answer 17

Pre-anaesthetic bloodwork reveals abnormalities in only 8% of patients with unremarkable physical exam

The likelihood to change your anaesthetic protocol or to postpone the anaesthetic based on results is 0.2% and 0.8% respectively

If the physical exam reveals abnormalities then this would be different, it is then vets decision whether bloodwork is required.

Question 18

How to plan an anaesthetic

Answer 18

Anticipate and list the potential complications

Identify a treatment/prevention option for each potential complication

Plan your anaesthetic protocol (drugs, doses and routes of administration)

Plan analgesic approach if needed

Question 19

Planning of post-operative care (2-12hrs)

Answer 19

Analgesia plan based on procedure and individual animal pain

Airway care and oxygen supplementation (e.g. After airway surgery, brachycephalic)

Post-operative fluids therapy

Support drugs (e.g. antiemetics, vasopressors, antiarrhythmics)

Diagnostic tests (e.g. BG, electrolytes, PCV and TS)

Question 20

Things to communicate to the owner before anaesthesia

Answer 20

Risk of peri-anaesthetic death

Possible sequels/consequences of GA

Will my animal suffer/feel pain?

Preference for sedation over GA (often the levels of sedation needed with be v high and therefore risk could be higher)

Question 21

Patient related risk factors for anaesthetic death

Answer 21

Small or young more likely to get hypothermia

Liver dysfunction: bleeding, hypoglycaemia and longer recover

Brachycephalic breeds: respiratory dysfunction/upper airway obstruction and high parasympathetic tone

Question 22

Procedure related risk factors for anaesthetic death

Answer 22

Arrhythmias during procedures involving heart catheterisation

Moderate to severe bleeding during adrenalectomy/invasive oncologic surgery

Respiratory impairment during thoracotomy

Vagal stimulation during oesophageal foreign body removal