Anaesthetics

Question 1

What are the different peri-operative risk scoring systems?

Answer 1

ASA and POSSUM.

Question 2

What is the ASA peri-operative risk scoring system?

Answer 2

ASA 1: healthy patient.
ASA 2: mild systemic disease; no functional limitation.
ASA 3: moderate systemic disease; have functional limitation.
ASA 4: severe systemic disease that is a constant threat to life.
ASA 5: moribund patient; unlikely to survive 24hrs, with or without treatment.
Postscript E: indicates emergency surgery.

Question 3

What is POSSUM scoring?

Answer 3

Risk prediction.
Enter patient physiological and operative variables.
Mortality and morbidity risk: pre-operative = risk discussion; peri-operative = need for invasive monitoring?; post-operative = over 5% mortality risk should go to HDU/ITU post-operative.

Question 4

What are the criteria for stability of patients for day stay surgery?

Answer 4

Social day stay factors: patient consent, carer, home setup.
Medical day stay factors: fitness, stable chronic, obesity not preclude.
Surgical day stay factors: complication risks, controllable post op symptoms, mobile.

Question 5

Why is there a nil by mouth policy before surgery, and what is the usual guidance?

Answer 5

Reduce aspiration risk.

Food: 6hrs; water: 2hrs; caveat: reflux, obesity, slow gastric transit e.g. trauma.

Question 6

How do you prescribe opioids, e.g. morphine?

Answer 6

Dose, form, strength (where appropriate), the total quantity or dosage units of the preparation in words and figures.
For instalment prescriptions, specify the instalment amount and instalment interval.
Handwritten.
Name, form and strength of drug and dose.
Your signature and date (include bleep no.)

Question 7

List 5 anti-emetic drugs.

Answer 7

Ondansetron
Cyclizine
Dexamethasone
Metoclopramide
Prochlorperazine

Question 8

What is the mechanism of action, dose, route, and side effects of ondansetron?

Answer 8

Mechanism of action = 5HT3R antagonist.
Side effects = bradycardia; long QT syndrome.
Dose/route = 4-8mg TDS; PO/IV.

Question 9

What is the mechanism of action, dose, route, and side effects of cyclizine?

Answer 9

Mechanism of action = H1 R antagonist.
Side effects = tachycardia; anti-cholinergic.
Dose/route = 50mg TDS; PO/slow IV/IM.

Question 10

What is the mechanism of action, dose, route, and side effects of dexamethasone?

Answer 10

Mechanism of action = corticosteroid.
Side effects = hyperglycaemia; perineal ‘burning’ (transient).
Dose/route = 4-8mg BD; IV.

Question 11

What is the mechanism of action, dose, route, and side effects of metoclopramide?

Answer 11

Mechanism of action = central DA2 R antagonist.
Side effects = extrapyramidal.
Dose/route = 10mg TDS; PO/IV.

Question 12

What is the mechanism of action, dose, route, and side effects of prochlorperazine?

Answer 12

Mechanism of action = DA antagonist.
Side effects = extrapyramidal; long QT syndrome.
Dose/route = 12.5mg BD; IM.

Question 13

Explain the WHO pain ladder.

Answer 13

Step 1: non-opioid, e.g. aspirin, paracetamol, or NSAID, ±adjuvant.
– pain persisting or increasing –
Step 2: weak opioid, for mild to moderate pain, e.g. codeine, ±non-opioid, ±adjuvant.
– pain persisting or increasing –
Step 3: strong opioid, for moderate to severe pain, e.g. morphine, ±non-opioid, ±adjuvant.

Question 14

Case 1: a poorly controlled asthmatic patient on oral steroids presents for emergency manipulation of a fractured radius, he is slightly breathless and wheezy at rest, describe your management.

Answer 14

Management of severe bronchospasm outside of theatre:
A,B,C.
O2: start high flow oxygen and gain IV access.
Salbutamol nebuliser 2.5-5mg.
Hydrocortisone 100mg IV 6-hourly or prednisolone orally 40-50mg/day.
Ipatropium nebuliser 0.5mg 4-6-hourly; IV salbutamol if not responding (250mcg slow bolus then 5-20mcg/min).
Theophylline/aminophylline.
Magnesium 2g IV over 20 minutes.
In extremis (decreasing conscious level or exhaustion), adrenaline may be used: nebuliser 5ml of 1 in 1,000; senior clinician only: IV 10mcg (0.1ml 1:10,000) increasing to 100mcg (1ml 1:10,0000) depending on response.

Question 15

What are the triggers of anaphylaxis?

Answer 15

Stings (wasp, bee, etc.)
Nuts
Food, e.g. milk, fish, chickpea, crustacean, etc.
Antibiotics, e.g. penicillin, cephalosporin
Anaesthetic drugs, e.g. suxamethonium, vecuronium
Other drugs, e.g. NSAID, ACEi, gelatins
Contrast media, e.g. iodinated
Other, e.g. latex, hair dye, hydatid

Question 16

How is anaphylaxis recognised?

Answer 16

ABCDE approach.
Airway problems: airway swelling, e.g. throat and tongue swelling (pharyngeal/laryngeal oedema); the patient has difficulty breathing and swallowing and feels that the throat is closing up; hoarse voice; stridor (high pitched inspiratory noise caused by upper airway obstruction).
Breathing problems: shortness of breath- increased respiratory rate; wheeze; patient becoming tired; confusion caused by hypoxia; cyanosis (appears blue), usually a late sign; respiratory arrest.
Circulation problems: signs of shock- pale, clammy; increased pulse rate (tachycardia); low blood pressure (hypotension)- feeling faint, dizzy, collapse, decreased conscious level or loss of consciousness; anaphylaxis can cause myocardial ischaemia and ECG changes even in individuals with normal coronary arteries; cardiac arrest.
Disability.
Exposure.

Question 17

How is anaphylaxis managed?

Answer 17

Call for help.
Lie patient flat.
Raise patient’s legs.

Adrenaline.

When skills and equipment available:
-establish airway
-high flow oxygen
-IV fluid challenge
-chlorphenamine
-hydrocortisone
Monitor:
-pulse oximetry
-ECG
-BP

Question 18

How is anaphylaxis diagnosed?

Answer 18

Look for:

• acute onset of illness
• life-threatening airway and/or breathing and/or circulation problems
• and usually skin changes

Question 19

What are the triggers for giving a blood transfusion?

Answer 19

Is the patient anaemic and haemodynamically stable? Is the HB >90g/L?
If yes: do not transfuse.
If no: does the patient have acute coronary syndrome, severe sepsis or neurological injury?
If no: general critical care: use a default Hb trigger of <70g/L with a target range 70-90g/L.
If yes:
-severe sepsis: early (<6hrs from onset), target Hb 90-100g/L; if evidence of tissue hypoxia, late (>6hrs from onset), target Hb >70g/L.
-neuro critical care: TBI and evidence of delayed cerebral iscahemia, target Hb 90g/L; subarachnoid haemorrhage, target Hb >80-100g/L
-ischaemic heart disease: patients with ACS, target Hb >80-90g/L; patients with stable angina, target Hb >70g/L.

Be less confident using an Hb trigger of 70g/L if patient is elderly, has significant cardiorespiratory co-morbidities, or inadequate tissue oxygenation.

Be more confident using an Hb trigger of 70g/L if patient is <55y/o and/or the severity of illness is relatively low.

Question 20

How does the NEWS work?

Answer 20

Like many existing EWS systems, based on simple scoring system in which a score is allocated to physiological measurements already undertaken when patients present to, or are being monitored in hospital.
6 simple physiological parameters form the basis of the scoring system: respiratory rate, oxygen saturations, temperature, systolic blood pressure, pulse rate, level of consciousness.
Score allocated to each measure.
Magnitude of score reflecting how extreme the parameter varies from the norm.
Score is then aggregated (uplifted if on oxygen).
Parameters are already routinely measured in hospitals and recorded on clinical chart.

Question 21

What are the indications for an arterial blood gas (ABG) sample?

Answer 21

To obtain and interpret oxygenation levels.
To assess for potential respiratory derangements.
To assess for potential metabolic derangements.
To monitor acid-base status.
To assess carboxyhemoglobin in CO poisoning.
To assess lactate.
To gain preliminary results for electrolytes and haemoglobin.
Can be conducted as a one off sample or repeated sampling to determine response to interventions.

Question 22

What are the contraindications for an arterial blood gas (ABG) sample?

Answer 22

Local infection.
Distorted anatomy.
Presence of arterio-venous fistulas.
Peripheral vascular disease of the limb to be sampled.
Severe coagulopathy or recent thrombolysis.

Question 23

What are the possible sampling errors in an arterial blood gas (ABG) sample?

Answer 23

Presence of air in the sample.
Collection of venous rather than arterial blood.
An improper quantity of heparin in the syringe, or improper mixing after blood is drawn.
Delay in specimen transportation.

Question 24

What are the possible complications related to arterial blood sampling?

Answer 24

Haematoma.
Nerve damage.
Arteriospasm or involuntary contraction of the artery.
Aneurysm of artery.
Fainting or a vasovagal response.

Question 25

Which 2 answers are used to define sepsis?

a) HR > 90
b) HR > 100
c) temp >38C
d) temp >39C

Answer 25

HR > 90

temp >38C

Question 26

Which arteries can be sampled for ABG analysis?

a) radial
b) ulnar
c) carotid
d) dorsalis pedis
e) femoral

Answer 26

All apart from carotid.