ANAESTHESIA - Anaesthetic Risk and Pre-Anaesthetic Assessment Flashcards
What is the ASA grading scale?
The ASA grading scale is a tool that vets use to assess a patient’s health status and assess the the risks associated with anaesthesia. This helps vets tailor anaesthetic protocols accordingly for each patient
Describe a patient with an ASA score of one
Healthy patient
Describe a patient with an ASA score of two
Patient with mild, fully compensated systemic disease
e.g. controlled diabetes, mild heart disease
Describe a patient with an ASA score of three
Patient with severe systemic disease functionally affecting the patient
e.g. uncontrolled diabetes, anaemia
Describe a patient with an ASA score of four
Patient with severe systemic disease which is a constant threat to life
e.g. shock, uncontrolled heart failure
Describe a patient with an ASA score of five
Patient is moribund, not expected to live for more than 24 hours without and possibly even with treatment
e.g. shock, severe trauma
What is meant by the addition of the letter ‘E’ to an ASA score?
The addition of an ‘E’ indicates this is an emergency case
(T/F) Most anaesthetic related deaths occur post-operatively
TRUE.
What is the most plausable theory behind more anaeasthetic deaths occuring in the post-operative period?
Most deaths occur within the post-operative period due to the withdrawal of monitoring and support in the recovery phase
According to mortality studies, what is the primary cause of anaesthetic related death in small animals?
Cardiorespiratory failure
According to mortality studies, what is the primary cause of anaesthetic related death in equids?
Post-anaesthetic injuries (such as fractures and myopathies)
According to veterinary evidence, identify ten risk factors that can increase anaesthetic risk
Patient ASA grade
Procedural urgency
Major procedures
Duration of procedure
Patient signalement (age, breed, body weight/conditon)
Concurrent disease
Fluid therapy in cats
Endotracheal intubation in cats
Mask inductions
Level of monitoring and degree of intervention by anaesthetist
How can fluid therapy increase anaesthetic risk in cats?
Excessively high volume fluid rates in cats increases the risk of volume overload
How can endotracheal intubation increase anaesthetic risk in cats?
There are more complications associated with endotracheal intubation in cats such as laryngeal spasm due to mechanical manipulation of the larynx, tracheal collapse and pressure necrosis due to overinflation of the cuff
How can mask induction increase anaesthetic risk?
Mask induction is often unpleasant and stressful for the patient which triggers the sympathetic nervous system resulting in catecholamine release which results in tachycardia. Severe tachycardia can result in decreased cardiac output as the heart does not have time to refill with blood - which can contribute to increased anaesthetic risk
What is the aim of a pre-anaesthetic assessment?
A pre-anaesthetic assessment aims to identify any disorders which may increase anaesthetic risk
What should you carry out during a pre-anaesthetic assessment?
Take a thorough history
Clinical exam
Which three main factors should you consider when determining anaesthetic risk?
Patient signalement (age, breed, body condition/weight)
Disease processes affecting the patient
Type of procedure taking place
Why do geriatric patients have a higher anaesthetic risk?
Geriatric patients have reduced physiological reserves, may have concurrent disease and are more prone to hypothermia
Why do paediatric patients (animals less than 12 weeks old) have a higher anaesthetic risk?
Paediatric patients are still physiologically immature and are more prone to hypothermia
Why do brachycephalic breeds have a higher anaesthetic risk?
Brachycephalic breeds have small collapsible airways that are prone to obstruction and severe respiratory impairment
Why do greyhounds have a higher anaesthetic risk?
Greyhounds have a very low body fat percentage which can lead to the faster absorption and elimination of anaesthetic drugs as well as affect drug distribution. Some drugs also have a longer duration of action in Greyhounds due to impaired drug metabolism by the liver
Why do some herding dog breeds have an increased anaesthetic risk?
Herding dog breeds often have a genetic mutation in the ABCB1 gene that allows certain drugs to cross the blood brain barrier (BBB) and accumulate in the brain
How can obesity increase anaesthetic risk?
Obesity increases the pressure on the cardiorespiratory system, the excess fat can affect drug distribution and duration of action and wound healing is impaired in obese animals
Which eight questions should you consider before putting your patient under anaesthesia?
- Has anything significant been identified in the history and/or clinical exam?
- Do any abnormalities warrant further investigation?
- Can any abnormalities be stabilised prior to anaesthesia?
- What complications are anticipated during anaesthesia?
- How can these complications be managed?
- Would the patient benefit from pre-medication?
- How will any pain associated with the procedure be managed?
- How will anaesthesia be induced and maintained?
When are pre-op blood tests most useful?
Pre-op blood tests are most useful in geriatric patients to check for and monitor any disease trends
When are pre-op blood tests unnecessary?
Evidence suggests that in patients below the age of seven with an ASA score of one, pre-op bloods are unnecessary
Other than the patient themselves, which five factors can also influence patient safety while under anaesthesia?
Organisation
Technology available
Medications and delivery systems available
The veterinary team
The individual monitoring the anaesthetic
