Anaesthetics

Question 1

Give 4 reasons why an elective surgery may be cancelled on the day?

Answer 1

• Current RTI
• Poor control of drug therapy
• Recent MI
• Poor bloodwork
• Uncontrolled HTN or AF
• Logistical issues e.g. emergency case

Question 2

What are 4 common risks of having anaesthesia/surgery?

4 rare but important?

Answer 2

Common: pain/aches, PONV, sore throat, confusion, dizziness, bladder problems.
Rare: allergy to medication, damage to teeth, slow breathing

Question 3

Name 1 non-depolarising neuromuscular blocking agents and 1 depolarising?

Answer 3

Non-depolarising = rocuronium, atracurium, pancuronium
Depolarising = suxemethonium

Question 4

What are possible induction agents for anaesthesia?

Answer 4

Propofol, thiopentone, ketamine, etomidate

Question 5

Which induction agent is mostly used for RSI?

Answer 5

Thiopentone

Question 6

Which induction agent is used for anaesthesia in TIVA?

Answer 6

Propofol

Question 7

Ketamine is more commonly used as an induction agents in ?

Answer 7

Paediatrics

Question 8

Name 3 inhalational agents used to maintain anaesthesia?

Answer 8

Isoflurane, desflurane, sevoflurane

Question 9

Outline the steps from an awake patient to an asleep patient ready for surgery.

Answer 9

• Pre-oxygenation
• Opioid
• Induction agent
• Inhalational agent for maintenance
• Bag mask
• Muscle relaxant and endo-tracheal intubation
• or just LMA insertion

Question 10

Outline the steps of a RSI.

Which drugs are typically used?

Which patient’s is it used for?

Answer 10

• Pre-oxygenation
• Sellick’s manoeuvre (cricoid pressure)
• Induction agent and immediate muscle relaxant
• Intubation

Thiopentone and suxamethonium

Used if risk of aspiration of gastric contents

Question 11

What are the steps involved at the end of an operation to wake a patient up?

Answer 11

• Stop anaesthetic vapours
• Give oxygen
• Suction
• Reverse muscle relaxants
• Once breathing = remove ET tube and give oxygen by mask
• Recovery

Question 12

What antiemetics are given

a) intraoperatively
b) post operatively?

Answer 12

Ondansetron and dexamethasone

Cyclizine

Question 13

Which is longer acting, lidocaine or bupivacaine?

Which is more toxic?

Answer 13

Bupivacaine

Bupivicaine

Question 14

What effect does adding adrenaline to local anaesthetic injection have?

Answer 14

Increased length of action and with lidocaine allows higher doses to be used.

Question 15

What is the mechanism of action of local anaesthetics?

What are the signs of toxicity?

Answer 15

Na+ channel blocks, prevents depolarisation of nerves

Peri-oral numbness, tinnitus, light-headedness, confusion, LoC, seizures, cardiac collapse.

Question 16

Management of local anaesthetic toxicity?

Answer 16

Supportive - airway support, cardiac monitoring
Benzos for seizures
IV 20% lipid emulsion (Itralipid) to absorb LA from circulatory system. Bolus and then infusion

Question 17

What are the layers you progress through when performing a spinal anaesthesia?
At which layers do you get a ‘pop’?

Answer 17

Skin - subcut fat - supraspinatous ligament - interspinatous ligament - ligamentum flavum (pop) - epidural space - dura mater (pop) - arachnoid mater - subarachnoid space

Question 18

What are some CI to spinal anaesthesia?

Answer 18

Local infection, sepsis, raised ICP, coagulopathies, severe hypovolaemia, pt refusal, severe MS and AS,

Question 19

SEs of spinal anaesthesia?

Answer 19

Hypotension, sensory and motor block, urinary retention.

Question 20

Which has a quicker onset: epidural or spinal?

Answer 20

Spinal.

Question 21

Complications of epidural?

How long do they usually stay in for?

Answer 21

Epidural haematoma/abscess, headache, infection, indwelling urinary catheter required.

Usually 2-3 days e.g. following major surgery. Can be shorter/longer.

Question 22

What is the Monro Kellie doctrine?

Answer 22

Sum of brain, CSF and intracerebral blood is constant, so increase in one must lead to decrease in one of the other.

Question 23

What is the equation for cerebral perfusion pressure?

Answer 23

Mean arterial pressure - mean intracranial pressure

Question 24

What is normal ICP?

Answer 24

7-15mmHg

Question 25

What is the Cushing’s triad for raised ICP?

Answer 25

Hypertension with widening pulse pressure
Bradycardia
Irregular breathing

Question 26

When must you not use vasoconstrictor with local anaesthetic?

Answer 26

For regional blocks of the digits e.g. ring block, as vasoconstriction can cause ischaemia of the digit

Question 27

Do local anaesthetics work on C fibres or A fibres first?

Answer 27

C fibres, which are smaller and transmit pain and temperature. A fibres are larger and transmit touch and power.

Question 28

What are 3 CI to the use of suxamethonium?

Answer 28

Penetrating eye injuries, acute narrow angle glaucoma, hyperK, recent burns, spinal cord trauma causing paraplegia, previous sux allergy.

Question 29

What patient would be classed as grade 1 ASA?

Answer 29

Healthy, non-smoker, non/minimal alcohol drinking

Question 30

For elective surgery, what is the advice regarding food and clear fluids beforehand?

Answer 30

No food for 6 hours before, no clear fluids for 2 hours before.

Question 31

Patients with MG are very sensitive to what type of anaesthetic agents?

Answer 31

Non-depolarising neuromuscular blocking agents e.g. rocuronium

Question 32

What is succinylcholine otherwise known as?

Answer 32

Suxamethonium

Question 33

What can be used to reverse non-depolarising nm blockade and what drug may be given with it?

Answer 33

Neostigmine

May be given with glycopyrronium bromide or atropine to prevent bradycardia and excessive salivation.

Question 34

What induction agent is suitable for a patient who is haemodynamically unstable? Why?

Answer 34

Ketamine -doesn’t cause hypotension unlike propofol and thiopental sodium

Question 35

What is the max safe dose of lidocaine?

And bupivacaine?

Answer 35

a) 3mg/kg

b) 2mg/kg