Inhalation Agents

Question 1

Sevoflurane Class

Answer 1

Fluorinated methyl isopropyl ether

Question 2

Sevoflurane Use

Answer 2

Induction and maintenance of general anesthesia

Question 3

Sevoflurane MOA

Answer 3

• Causes a reduction in nerve transmission at synapses
• Affects the function of ion channels and neurotransmitter receptor proteins in the membranes of nerve cells
• GABAa stimulation producing a supraspinal inhibition of transmission
• Inhibition of glutamate channels

Question 4

Sevoflurane Dose

Answer 4

MAC 2%, dose dependent on age

Question 5

Sevoflurane Pharmacokinetics

Answer 5

Gas partition coefficient 0.65

Metabolism: minimal hepatic metabolism or renal excretion, approx 2%

Question 6

Sevoflurane Contraindications

Answer 6

Malignant Hypertension and hypersensitivity

Question 7

Sevoflurane Considerations

Answer 7

• Not irritating to the airway, best for induction
• Produces bronchodilation
• Combustion risk in desiccated absorber, can also form compound A

Question 8

Desflurane Class

Answer 8

Fluorinated methyl ether ether

Question 9

Desflurane Use

Answer 9

Induction and maintenance of general anesthesia

Question 10

Desflurane MOA

Answer 10

• Causes a reduction in nerve transmission at synapses
• Affects the function of ion channels and neurotransmitter receptor proteins in the membranes of nerve cells
• GABAa stimulation producing a supraspinal inhibition of transmission
• Inhibition of glutamate channels

Question 11

Desflurane Dose

Answer 11

MAC 4 - 6%

Question 12

Desflurane Pharmacokinetics

Answer 12

Blood gas partition coefficient 0.42, fastest onset of the volatile gasses
0.02% metabolized by cytochrome P-450 → trifluoroacetate

Question 13

Desflurane Contraindications

Answer 13

Malignant Hypertension
Do not use as an inhalational agent
Do not use with reactive airway disease
Liver impairment

Question 14

Desflurane Considerations

Answer 14

Needs a special heated vaporizer
Low boiling point
Irritating to airways
Tachycardia

Question 15

Isoflurane Class

Answer 15

Halogenated methyl ethyl ether

Question 16

Isoflurane Use

Answer 16

Induction and maintenance of general anesthesia

Question 17

Isoflurane MOA

Answer 17

• Causes a reduction in nerve transmission at synapses
• Affects the function of ion channels and neurotransmitter receptor proteins in the membranes of nerve cells
• GABAa stimulation producing a supraspinal inhibition of transmission
• Inhibition of glutamate channels

Question 18

Isoflurane Dose

Answer 18

MAC 1.2%

Question 19

Isoflurane Pharmacokinetcs

Answer 19

Slow onset due to high blood solubility 1.4

Good for liver disease since there is only 0.2% metabolism

Question 20

Isoflurane Contraindications

Answer 20

Malignant Hyperthermia

Question 21

Isoflurane Considerations

Answer 21

Irritating to the airway and not degraded or flammable

Question 22

Nitrous Oxide Class

Answer 22

Non-volatile inhalational agent, inorganic compound

Question 23

Nitrous Oxide Use

Answer 23

Induction and maintenance of general anesthesia

Question 24

Nitrous Oxide MOA

Answer 24

Inhibit NMDA receptor

Question 25

Nitrous Oxide Dose

Answer 25

MAC 105%

Question 26

Nitrous Oxide Pharmacokinetics

Answer 26

Fastest onset of any inhalational gas due to its blood gas coefficient of 0.46
Excretion: lungs (primarily unchanged)

Question 27

Nitrous Oxide Contraindications

Answer 27

Risk of air emboli; bowel cases, pneumothorax
Teratogenic, avoid with pregnancy
Fire risk cases → supports combustion

Question 28

Nitrous Oxide Considerations

Answer 28

• Analgesic yet minimal skeletal muscle relaxation
• Unique properties of nitrous are the reason for the second gas and concentration effect
• Adverse affect = diffusion hypoxia… therefore you should oxygenate with 100% O2
• DOES NOT TRIGGER MALIGNANT HYPERTHERMIA