General Anaesthetics

Question 1

What are the main two types of GA?

Answer 1

Inhalational
(nitrous oxide)
Intravenous
(halogenated hydrocarbons, barbiturates, steroids)

Question 2

What are the main targets of GAs?

Answer 2

GABA and GABAaRs, two pore domain K+ channels

Question 3

How do intravenous and inhalational GAs effect their targets differently

Answer 3

Intravenous- bind only to the beta subunit of GABAa receptors
Volatile GAs- bind to interface of alpha and beta subunits of GABAa

Question 4

Difference (of effect on neurotransmission) between low and high concentrations of GAs

Answer 4

Low-
unconsciousness, short term amnesia, analgesia
High-
loss of: motor control, reflexes, autonomic regulation (death)

Question 5

What are the 4 stages of anaesthesia

Answer 5

1. Analgesia
2. Excitement
3. Surgical anaesthesia
4. Medullary paralysis

Question 6

Advantages and disadvantages of intravenous GAs

Answer 6

ADVS-
easy to administer
rapid induction
propofol- rapid metabolism, small 'hangover'
DISADVS-
pain at site of injection
complex pharmokinetics
short duration of action due to redistribution 
hangover due to accumulation in body fat
potentially fatal side fx

Question 7

4 factors affecting the depth of inhalational GAs

Answer 7

1. Conc of drug in inspired gas
2. Rate of pulmonary ventilation
3. Transfer from alveoli to blood (blood:gas coefficient)
4. Loss of drug to fat

Question 8

Symptoms of malignant hyperthermia

Answer 8

Tachycardia
Rising body temperature
Hypertension
Increased muscle contraction