Anaesthetics

Question 1

AIRWAY MANAGEMENT

What is the stepwise management of airway management?

Answer 1

• Simple positional manoeuvres = head tilt chin lift, jaw thrust
• Oropharyngeal or nasopharyngeal (relative C/I is base of skull fractures)
• Supraglottic airway (laryngeal mask/iGel) but poor control against reflux
• Endotracheal intubation (last resort tracheostomy)

Question 2

ANAESTHETIC AGENTS
What are IV agents used for?
Give some examples and their mechanism?

Answer 2

• Induction for theatre, maintenance in ICU
• Propofol = GABA agonist
• Ketamine = NMDA antagonist

Question 3

ANAESTHETIC AGENTS
What are some unique features about…

i) propofol?
ii) ketamine?

Answer 3

i) Pain on injection, some anti-emetic effects, avoid in egg/soya allergy
ii) Little myocardial depression so optimum if haemodynamically unstable (trauma)

Question 4

ANAESTHETIC AGENTS
What are inhalation agents used for?
Give some examples
What are some adverse effects?

Answer 4

• Induction + maintenance
• Sevoflurane, desflurance
• Malignant hyperthermia, myocardial depression

Question 5

ANAESTHETIC AGENTS

What are the two types of muscle relaxants, their mechanism of action and examples?

Answer 5

• Non-depolarising = competitive antagonist of nicotinic ACh receptors (atracurium, rocuronium)
• Depolarising = binds to nicotinic ACh receptors resulting in persistent depolarisation of the motor end plate (suxamethonium)

Question 6

ANAESTHETIC AGENTS
What are some adverse effects of suxamethonium?
What are some contraindications?

Answer 6

• Malignant hyperthermia, hyperkalaemia, fasciculations

- Penetrating eye injuries, acute glaucoma as increased IOP

Question 7

ANAESTHETIC AGENTS
What is malignant hyperthermia?
How does it present?
What is the management?

Answer 7

• Rare autosomal dominant condition
• Hyperpyrexia + muscle rigidity (raised CK)
• Dantrolene = prevents calcium release

Question 8

ANAESTHETIC AGENTS

What is used for a rapid sequence induction?

Answer 8

• Sodium thiopentone and suxamethonium

Question 9

PRE-OPERATIVE MANAGEMENT

What are the rules on fasting before surgery?

Answer 9

• Clear fluids = until 2h before

- Non-clear fluids/food = until 6h before

Question 10

PRE-OPERATIVE MANAGEMENT

What are the rules about cardiovascular drugs and when to stop them?

Answer 10

• Clopidogrel = 7d before
• Warfarin = 5d before and bridge with LMWH until night before
• ACEi = day before

Question 11

PRE-OPERATIVE MANAGEMENT

How do you manage diabetes pre-operatively?

Answer 11

• On insulin and good glycaemic control (HbA1c <69) with minor procedures = adjust usual insulin regimes
• Surgery >1 missed meal or poorly controlled = VRII
• PO antidiabetic drugs usually manipulated day of surgery

Question 12

PRE-OPERATIVE MANAGEMENT
How do you manage the following drugs pre-operatively…

i) metformin?
ii) sulfonylureas?
iii) DPP4 inhibitors?
iv) GLP-1 analogues?
v) OD insulins (Lantus, Levemir)?

Answer 12

i) OD/BD = take normally, TDS = omit lunch dose
ii) Omit doses unless morning surgery and take BD then omit just morning
iii) Take as normal
iv) Take as normal
v) Reduce dose by 20% day before, of and after

Question 13

PRE-OPERATIVE MANAGEMENT

What is the management of COCP/HRT pre-operatively?

Answer 13

• Stop 4w before and start 2w after

Question 14

PRE-OPERATIVE MANAGEMENT

What forms the pre-operative assessment?

Answer 14

• Mallampati score
• Jaw movement = thryomental + sternomental distance
• Range of motion in neck