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Flashcards in GA Deck (23)
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1
Q

Which inhaled general anaesthetic has some significant metabolic degradation from CYP450 enzymes?

A

Halothane. Approximately 20% metabolised.

2
Q

Which three inhaled anaesthetics are most likely to have liver toxicity (in descending order of likelihood)?

A

Halothane
Isoflurane
Desflurane

3
Q

If you were seeking a more potent anaesthetic, would you want a smaller or higher MAC?

A

Smaller. If it’s a smaller concentration required to produce no response to surgical stimulus, that implies a higher potency.

4
Q

Lipid solubility is directly proportional or inversely proportional to MAC?

A

Inversely proportional.

An increasing lipid solubility indicates a more potent anaesthetic, meaning less concentration for an effective dose, i.e. lower MAC.

5
Q

What do gaseous anaesthetics do on a cellular level?

A

Stabilise the open state of the GABAA receptor and stabilise the closed or desensitised state of the nicotinic receptor.

6
Q

How do fatty tissues affect anaesthesia?

A

It acts as a resevoir for the anaesthetic during recovery, lengthening the time of recovery.

7
Q

How significant is metabolic degradation of inhaled anaesthetics?

A

It is very insignificant. It is more important to monitor induction/recovery and respirations to determine duration of action.

8
Q

What is MAC?

A

Minimum alveolar concentration required to have 50% of humans to have no surgical response.

9
Q

If a patient has mainly lean tissues, will they reach anaesthetic equillibrium quicker or slower?

A

Quicker.

10
Q

What anaesthetics can cause a sympathetic discharge?

A

Nitrous oxide and ketamine.

11
Q

Intravenous anaesthetics have a duration of action that is long or short?

A

Short.
Thiopentone: 5-10mins.
Propofol: 2-4mins

12
Q

What are the stages of anaesthesia (Guedel’s signs)? What does each mean clinically?

A
  1. Induction (Pt doesn’t respond to questions)
  2. Excitement (Pt struggles, coughs, may experience bronchospasm and vomitting)
  3. Surgical anaesthesia
  4. Medullary depression (Leads to cardiorespiratory collapse - is a state of overdose)
13
Q

Propofol and thiopentone, which one is the barbituate?

A

Thiopentone.

14
Q

Name the five in-use inhaled general anaesthetics.

A
Nitrous Oxide
Sevoflurane
Haloflurane
Isoflurane
Desflurane
15
Q

Low solubility (low blood/gas coefficient) indicates what about the rate of induction and what about the rate of recovery?

A

Fast rate of induction and fast rate of recovery.

16
Q

High solubility (high blood/gas) coefficient indicates what for rate of induction and what for rate of recovery?

A

Slow rate of induction and recovery.

17
Q

Regarding inhaled general anaesthetics, halogenation increases or decreases potencty?

A

Increases potency.

18
Q

If a patient’s rate of ventilation is increased, what happens to the rate of induction?

A

It increases as well.

19
Q

What are some effects on the CVS from inhaled anaesthetics?

A

Decreased heart contractility (halothane first, then D/I/S)
Decreased sympathetic activity (halothane and sevflurane)
Decreased systemic vascular resistance (des/iso/sev)
Arrythmias (halo, D/I/S)

20
Q

Intravenous anaesthetics are not suitable for?

A

Maintaining anaesthesia.

21
Q

What are the five aims of ‘balanced anaesthesia’?

A
LOC
Amnesia
Relaxation of skeletal muscle 
Analgaesia 
Blunting of ANS responses
22
Q

Which of the intravenous anaesthetics has less chance of producing respiratory depression?

A

Ketamine.

23
Q

Intravenous anaesthetics have a duration of action that is long or short?

A

Short.
Thiopentone: 5-10mins.
Propofol: 2-4mins