Principles and Pharmacology

Question 1

Give four examples of IV anaesthetic drugs (general anaesthesia)

Answer 1

Thiopentone (aka thiopental sodium)
Propofol
Etomidate
(Ketamine)

Question 2

What is minimum alveolar concentration (MAC)?

Answer 2

MAC is the concept of the concentration of the drug required in the alveoli which is required to produce anaesthesia with any particular agent. Therefore, a low MAC value means an agent is potent.

Question 3

Give five examples of inhaled analgesic drugs

Answer 3

Isoflurane
Desflurane
Sevoflurane
Nitrous oxide

Question 4

What is the most common sequence of general anaesthesia?

Answer 4

Intravenous induction followed by inhalational maintenance.

Question 5

Describe the indications for muscle relaxants

Answer 5

ventilation & Intubation
when immobility is essential e.g. microscopic surgery, neurosurgery
body cavity surgery (access)

Question 6

Describe the potential problems associated with muscle relaxants

Answer 6

awareness

incomplete reversal
- airway obstruction, ventilatory insufficiency in immediate post op period

apnoea = dependence on airway & ventilatory support

Question 7

Give two classifications of muscle-relaxing drugs

Answer 7

Non-depolarising neuromuscular blocks

Depolarising neuromuscular blocks

Question 8

What is the “triad” of anaesthesia?

Answer 8

Analgesia
Hypnosis (unconsciousness)
Relaxation

Question 9

What effects do general anaesthetics have on the cardiovascular system?

Answer 9

Depress CV centre

• reduce sympathetic outflow
• negative inotropic/chronotropic effect on the heart
• vasodilation

Question 10

What effects do general anaesthetics have on the respiratory system?

Answer 10

Respiratory depression

• reduced hypoxic/hypercapnoeaic drive
• greatly decreased tidal volume; can persist for several days post-op
• increase respiratory rate

Paralyse cilia

Question 11

What are the two main possible airway complications of general anaesthesia?

Answer 11

Obstruction
- including laryngospasm
Aspiration
- gastric contents, blood, surgical debris

Question 12

Describe the indications for intubation

Answer 12

Protect airway from gastric contents
Need for muscle relaxation and therefore artificial ventilation
Shared airway with risk of blood contamination
Need for tight control of blood gases (e.g. neurosurgery)
Restricted access to airway

Question 13

Describe the indications for regional anaesthesia

Answer 13

avoidance of general anaesthesia
severe resp disease
•	less resp physiological impact
avoid airway problems
•	difficult intubation
•	obstruction (OSA)
allergies / reactions to GA agents

Question 14

Describe the contra-indications for regional anaesthesia

Answer 14

Patient refusal
Fixed cardiac output 
•	aortic / mitral stenosis
Infection
Bleeding diathesis / anticoagulation
Technical difficulties
Spinal problems / neurology

Question 15

Give five examples of local anaesthetics

Answer 15

Lignocaine (aka lidocaine)
Bupivacaine
Prilocaine
Ropivacaine
Levobupivacaine

Question 16

How do local anaesthetic agents work?

Answer 16

They are sodium channel blockers: prevent propagation of the action potential

Question 17

List the possible signs and symptoms of local anaesthetic toxicity

Answer 17

Circumoral and lingual numbness and tingling
Light-headedness
Tinnitus,  visual disturbances
Muscular twitching
Drowsiness
Cardiovascular depression
Convulsions
Coma
Cardiorespiratory arrest