Inhalational anaesthetics

Question 1

Which inhalational anaesthetic is the best we know of?

Answer 1

Desflurane

expensive

Question 2

Which inhalational anaesthetic is banned in the EU?

Answer 2

Halothane

Question 3

Which anaesthetics are liquids (but gasses at high temp)?

Answer 3

Halothane, isoflurane, sevoflurane etc.

Question 4

Which anaesthetic is a true gas?

Answer 4

Nitrous oxide (N2O)

Question 5

Name the inhalational anaesthetics.

Answer 5

1) Halothane (not used)
2) Isoflurane
3) Sevoflurane
4) Desflurane
5) Nitrous oxide

Question 6

Inhalational anaesthetics mechanism of action.

3

Answer 6

1) Disrupt neuronal membranes and thus ion channels → cannot work properly → sedation
2) GABAa-agonist
3) Blocks neurotransmitter release in the brain

Question 7

What is MAC, and what does it stand for?

Answer 7

Minimal alveolar concentration

The concentration in air at which 50% of animals will not react to surgical stimulus (cut).

Usually 2xMAC is necessary for operations.

Question 8

List the inhalational anaesthetics from most to least potency.

Answer 8

Halothane (not used)

Isoflurane (freq. used)

Sevoflurane (freq.
used)

Desflurane

Nitrous oxide (not used alone, only analgesic effect)

Question 9

What does it mean when an inhalational anaesthetic has good solubility in blood?

Answer 9

lung→blood→brain

It means that the gas will take a long time to saturate the blood, and will have difficulties leaving the blood and enter the brain.

Question 10

Which is favoured in regards to inhalation anaesthetics, good or bad solubility in blood?

Answer 10

Bad solubility.

Because the gas does not want to be in the blood and moves quickly into the brain.

Better government, faster recovery, less excitation.

Question 11

List the inhalational anaesthetics from best to worst solubility in blood.

Answer 11

Halothane

Isoflurane

Sevoflurane (best drug to use)

Desflurane

Nitrous oxide

Question 12

Inhalational anaesthetics pharmacological effects.

5

Answer 12

(similar to propofol)

1) Total unconsciousness
2) Ø analgesia (must add morphine/fentanyl)
3) Muscle relaxation
4) Bronchodilation (imp. in asthma patients)
5) Anti-convulsion

Question 13

Inhalational anaesthetics side effects.

8

Answer 13

1) Cardiovascular depression
2) Local tissue irritation
3) Bronchospasm (isoflurane can only be given to sleeping animals or rodents)

4) Pre- and post-narcotic excitation (halothane > isoflurane&raquo_space; sevoflurane)
Better sol. = increased risk of excitation.

5) Halothane: hepatotoxic because 20-50% met. in liver.
(Isoflurane + sevoflurane only 1%. Rest exhaled unchanged)

6) Halothane: teratogenic, carcinogenic, immunotoxic.
7) Halothane: lethal hyperthermia

8) Nephrotoxicity: Flurane met → triluoracetic acid + fluorides → nephrotoxic molecules (but low amounts)
Reduce risk: always give IV fluids