Introduction

Question 1

General Anaesthetic Agents

Answer 1

Interfere with neuronal ion channels
Hyperpolarise neurones = Less likely to “fire” (opening chloride channels)

Inhalation agents dissolve in membranes

Intravenous agents – allosteric binding
GABA receptors – open chloride channels

Cerebral function “lost from top down”
Most complex processes interrupted first
Reflexes relatively spared

Question 2

Inhalational Anaesthetics

Answer 2

Halogenated hydrocarbons

Uptake and excretion via lungs

• concentration gradient - lungs > blood > brain
• cross alveolar BM easily
• arterial concn = closely to alveolar partial pressure

MAC = minimum alveolar concentration

• Measure of potency
• Low MAC = high potency (effect)

Question 3

Drugs

Answer 3

Inhalational anaesthetics
Intravenous anaesthetics
Muscle relaxants
Local anaesthetics
Analgesics

Question 4

Techniques & Equipment

Answer 4

Tracheal intubation
Ventilation
Fluid therapy
Regional anaesthesia
Monitoring

Question 5

Inhalational Awakening

Answer 5

stop inhalational admin

Question 6

Inhalational washout

Answer 6

reversal of concentration gradient

Question 7

Inhalational Induction

Answer 7

slow

Question 8

Inhalational Maintenance of anaesthesia

Answer 8

prolong duration - very flexible

Question 9

Inhalational Agents

Answer 9

Halothane

Desflurane

Question 10

Intravenous Agents

Answer 10

Thiopentane

Propofol

Question 11

Signs and symptoms of local anaesthetic toxicity

Answer 11

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

Question 12

Why intubate?

Answer 12

Protect airway from gastric contents
e.g. full stomach in an unfasted emergency patient

Need for muscle relaxation - artificial ventilation
e.g. laparotomy (muscle relaxants are not selective!)

Shared airway with risk of blood contamination
e.g. tonsillectomy in ENT

Need for tight control of blood gases
especially CO2 levels in Neurosurgery

Restricted access to airway
e.g. Maxillo-facial surgery

Question 13

The risks to an unconscious patient

Answer 13

“Airway, Airway, Airway”
Temperature

Loss of other protective reflexes
eg corneal, joint position

Venous thromboembolism risk
Consent & Identification
Pressure areas

Question 14

Na+ requirements:

Answer 14

1 – 2mmol/kg/day

Question 15

K+ requirements:

Answer 15

0.5 – 1mmol/kg/day

Question 16

Fluid requirements:

Answer 16

25-30ml/kg/day

Question 17

Glucose requirements:

Answer 17

50-100g/day