Anaesthetics: Pre-Operative Assessment Flashcards
What is the American Society of Anaesthetist (ASA) Scoring System?
Used routinely as part of the WHO Safer Surgery Checklist.
A grading system to determine the health of a person before a surgical procedure that requires anesthesia.
Described stages 1-6 of the ASA
1 - Normal health patient
2 - Mild systemic disease (e.g. asthma)
3 - Severe systemic disease
4 - Severe systemic disease that is a constant threat to life
5 - Moribumd patient, not expected to survive without the operation
6 - Declared brain-dead patient, organ removal for donor purposes
Give brief structure of anaesthetic pre-operative assessment
1) Previous anaesthetics
2) Allergies & intolerances
3) Medication history
4) Presenting complaint
5) PMH
6) Fasting period
7) Airway assessment
What are some key questions to ask about previous anaesthetics in the pre-operative assessment (POA)?
1) Has the patient had any previous anaesthetics? If so, was that under general anaesthetic or another method? – e.g. peripheral nerve blocks, spinal, epidural and/or sedation
2) Did they have any problems with previous anaesthetics?
3) Serious anaesthetic complications:
- malignant hyperthermia
- suxamethonium apnoea
- anaphylaxis
- difficult airway
4) Did they experience postoperative nausea and vomiting previously?
What is malignant hyperthermia?
A rare reaction to volatile anaesthetic agents and neuromuscular blocking drugs that can cause dangerously high body temperature and muscle contractions.
What is suxamethonium apnoea?
A deficiency in enzymes required to break down suxamethonium, resulting in prolonged paralysis of skeletal muscle.
During POA, if a patient says something like “Oh I was slow to wake up”, what should you ask?
Important to determine how seriously they were affected:
1) How long did they take to wake up? Was it a few hours or a few days?
2) Did they require intensive treatment unit (ITU) admission post-op due to problems waking up?
3) Is there any family history of problems with anaesthetics?
4) Have they or their family members had any specific testing? – i.e. genetic, allergy or other testing relating to anaesthetic agents (MH or suxamethonium apnoea)
How can you help to distinguish between an allergy and an intolerance?
Ask what kind of reaction they had to each medication e.g. rash, swelling, anaphylaxis, nausea/diarrhoea
What should you SPECIFICALLY ask about when discussing allergies & intolerances in POA?
Penicillin & NSAIDs
What should you SPECIFICALLY ask about when discussing medication history in POA?
1) anticoagulants
2) antiplatelets
3) antihypertensives
4) analgesics & when they last took them
5) “over the counter” and herbal medications.
Key questions to ask when discussing PMH in POA?
1) Who manages their chronic condition?
2) Recent GP visits and hospital admissions relating to a chronic condition
3) Recent changes in treatment
4) Associated complications of condition and body systems affected
Example questions to ask about asthma/COPD when discussing PMH in POA:
1) Regular medications, compliance and degree of control
2) Recent oral steroid treatment
3) Exacerbating factors
4) Smoking status
Example questions to ask about diabetes when discussing PMH in POA:
1) How is it controlled? Diet, oral medication or insulin?
2) How often do they check their capillary blood glucose and what’s normal for them?
3) Do they still have hypo-awareness?
How can a history of GORD affect anaesthetics?
Significant reflux would require rapid sequence induction and intubation to reduce the risk of stomach contents contaminating the airway.
Questions to ask about GORD in POA?
1) Triggers – e.g. food, lying supine
2) Associated symptoms – discomfort, acid into throat/mouth
3) Frequency and the most recent episode
4) How is it controlled?
What is it important to as women of reproductive age in POA?
1) could they be pregnant?
2) when was their last menstrual period?
Water fasting period before anaesthetics?
up to 2 hours before induction of anaesthetic
Fasting period before anaesthetics for food or milk-containing products?
up to 6 hours before induction of anaesthetic
Chewing gum before anaesthetics?
Up to 2 hours before
What is the purpose of Wilson’s score?
Can indicate how difficult an airway will be.
What Wilson’s score suggests easy laryngoscopy?
<5
What Wilson’s score suggests potentially difficult laryngoscopy?
5-8
What Wilson’s score suggests indicates a risk of severe difficulty in laryngoscopy?
8-10
What score is used to predict the ease of endotracheal intubation?
The Mallampati score
What does the Mallampati test comprise?
The test comprises a visual assessment of the distance from the tongue base to the roof of the mouth, and therefore the amount of space in which there is to work.
What is involved in the ‘airway assessment’ in POA?
1) Wilson’s score
2) Mallampati score
3) Dentition e.g. caps, crowns, wobbly teeth
Does warfarin need to be stopped prior to surgery?
If minor superficial surgery e.g. ophthalmic or minor dental procedures) –> NO
For all other surgeroes –> the last dose of warfarin should be given 6 days before the procedure.
When should warfarin be stopped prior to surgery?
6 days
For emergency surgery or surgery where warfarin was not omitted, what should you check?
1) check INR
2) consider reversal with Vitamin K or other agents according to procedure and timeframe.
What do ‘bridging therapies’ refer to?
The use of alternative anticoagulation therapy, such as short-acting LMWH, during the pre- and immediately postoperative period.
See hospital protocol.
How is unfractionated heparin (UH) usually given?
is short-acting and normally given via IV infusion
How soon before a neuraxial block should heparin be stopped?
4 hours before (with evidence of a normal APTT)
