Vet 415 Anesthetic Drugs

Front 1

What is the mechanism of action of anesthetic inhalants?

Back 1

Act in the CNS, but exact MOA is unknown. They cause unconsciousness, amnesia, and immobility.

Front 2

Why is sevoflurane supplied in plastic bottles instead of glass?

Back 2

Sevoflurane can react with glass and so, is not stable in it.

Front 3

Rank these inhalants in order from least to most soluble: Sevoflurane, Isoflurane, Desflurane. What are the implications?

Back 3

Desflurane < Sevoflurane < Isoflurane. The less soluble the drug, the faster the patient undergoes anesthetic induction and recovery.

Front 4

How are inhalant anesthetics cleared by the body?

Back 4

Primarily eliminated by ventilation. Only a small proportion of drug is metabolized by the body.

Front 5

What do we use as a reference point when figuring out dosages of anesthetic inhalants?

Back 5

Minimum alveolar concentration (MAC) is the most commonly used reference point; MAC is the concentration of an inhaled anesthetic that prevents gross movement in response to a noxious stimulus in 50% of test subjects. MACs are determined in lab conditions and in healthy animals.

Front 6

What are some factors that decrease MAC?

Back 6

-Sedatives / analgesics / injectable anesthetics.
-Systemic DZ
-Hypothermia
-PaCO2 > 90 mmHg
-PaO2 < 40 mmHg
-PCV < 10%
-Older age
-Pregnancy

Front 7

What organ systems are affected by anesthetic inhalants?

Back 7

CNS - Depression, but reversible. No analgesia.
Respiratory - Depression.
Cardiovascular - Depression.
Other - Effects on other organs are secondary to the reduced cardiac output. Volatile anesthetics can trigger malignant hyperthermia.

Front 8

Compare isoflurane and sevoflurane.

Back 8

Sevoflurane is less soluble --> Vaporizer setting should be set slightly higher. Induction and recovery should be faster.
Sevoflurane is more expensive.
Sevoflurane is less pungent than isoflurane --> Better tolerated by animal if using it to induce.

Front 9

Inhalant induction can be stressful for animals, as it is relatively slower than IV anesthetic induction. Why would we choose to use it?

Back 9

1. Use if it is difficult to obtain IV access and IM administration is undesirable.
2. Use if animal is a neonate; they have poorly developed metabolic pathways.
3. Use if you have an unusual species; inhalants work on everything!

Front 10

Name some anesthetic inhalants.

Back 10

Isoflurane, sevoflurane, desflurane.

Front 11

Name some injectable anesthetics.

Back 11

Propofol, ketamine, etomidate, telazol.

Front 12

How are injectable anesthetics used?

Back 12

They are commonly used initially to induce general anesthesia. It is then maintained using an inhalational anesthetic. They can also be used to maintain anesthesia of short duration. Less frequently, they are used to maintain anesthesia of long duration.