Inhalation Agents Flashcards
Sevoflurane Class
Fluorinated methyl isopropyl ether
Sevoflurane Use
Induction and maintenance of general anesthesia
Sevoflurane MOA
- 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
Sevoflurane Dose
MAC 2%, dose dependent on age
Sevoflurane Pharmacokinetics
Gas partition coefficient 0.65
Metabolism: minimal hepatic metabolism or renal excretion, approx 2%
Sevoflurane Contraindications
Malignant Hypertension and hypersensitivity
Sevoflurane Considerations
- Not irritating to the airway, best for induction
- Produces bronchodilation
- Combustion risk in desiccated absorber, can also form compound A
Desflurane Class
Fluorinated methyl ether ether
Desflurane Use
Induction and maintenance of general anesthesia
Desflurane MOA
- 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
Desflurane Dose
MAC 4 - 6%
Desflurane Pharmacokinetics
Blood gas partition coefficient 0.42, fastest onset of the volatile gasses
0.02% metabolized by cytochrome P-450 → trifluoroacetate
Desflurane Contraindications
Malignant Hypertension
Do not use as an inhalational agent
Do not use with reactive airway disease
Liver impairment
Desflurane Considerations
Needs a special heated vaporizer
Low boiling point
Irritating to airways
Tachycardia
Isoflurane Class
Halogenated methyl ethyl ether
Isoflurane Use
Induction and maintenance of general anesthesia
Isoflurane MOA
- 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
Isoflurane Dose
MAC 1.2%
Isoflurane Pharmacokinetcs
Slow onset due to high blood solubility 1.4
Good for liver disease since there is only 0.2% metabolism
Isoflurane Contraindications
Malignant Hyperthermia
Isoflurane Considerations
Irritating to the airway and not degraded or flammable
Nitrous Oxide Class
Non-volatile inhalational agent, inorganic compound
Nitrous Oxide Use
Induction and maintenance of general anesthesia
Nitrous Oxide MOA
Inhibit NMDA receptor
Nitrous Oxide Dose
MAC 105%
Nitrous Oxide Pharmacokinetics
Fastest onset of any inhalational gas due to its blood gas coefficient of 0.46
Excretion: lungs (primarily unchanged)
Nitrous Oxide Contraindications
Risk of air emboli; bowel cases, pneumothorax
Teratogenic, avoid with pregnancy
Fire risk cases → supports combustion
Nitrous Oxide Considerations
- 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
