General Anesthetics

Question 1

What are the two ways that anesthetics can work?

Answer 1

• inhibit excitatory tone of NMDA receptors

- activate inhibitory GABA receptors

Question 2

What are the stages of medication of general anesthetics?

Answer 2

1. Premedication - typically benzodiazepines
2. Induction - typically IV medications
3. Maintenance - typically inhalation anesthetics

Question 3

What is typical of parenterally administered anesthetics?

Answer 3

Usually very hydrophobic. Flows into brain/CNS first, then redistributes into the body, so fast action.
Action of the drug is typically shorter than the half-life

Question 4

What general anesthetic can cause a prolonged hangover feeling?

Answer 4

Sodium Thiopental. Very long half life of ~12 hours due to getting into adipose and slowly leaking out.

Question 5

What general anesthetic that has antiemetic properties and less hang-over compared to sodium thiopental?

Answer 5

Propofol.

Question 6

What are side effects of anesthetic barbiturates?

Answer 6

CV and Respiratory depression. Decreases Pre-load, so problematic for cardiomyopathy, but not for CAD due to intact pre-load. Can also cause hypotension (due to lowering preload)

Question 7

What anesthetic is used when the patients have a risk of hypotension/cardiomyopathy?

Answer 7

Etomidate.

Safer in patient’s with CV risk, compared with propofol.

Question 8

What are unique side effects of Etomidate?

Answer 8

Suppression of adrenal response, causing increased risk of mortality. Primarily only used to induce anesthesia in CV risk patients.
Less respiratory depressant and increased nausea/vomiting

Question 9

What anesthetic can have the side effect of emergence delirium?

Answer 9

Ketamine

Question 10

What the unique clinical effects of Ketamine?

Answer 10

“Dissociative” Anesthesia, eyes open and unresponsive. NO effects on respiration.
NMDA receptor antagonist

Question 11

When is Ketamine used clinically?

Answer 11

Short procedures in children and patients who have bronchospasms.

Question 12

Side effects of Ketamine?

Answer 12

Spontaneous movement, salivation/lacrimation, increased intracranial pressure due to cranial blood flow

Question 13

What drug is typically used for pre-medicating?

Answer 13

Midazolam - prodrug, GABA-A activator

Question 14

What benzodiazepine is used for conscious sedation?

Answer 14

Midazolam

Question 15

What are the side effects of Midazolam?

Answer 15

Respiratory distress/arrest and decreases preload/hypotension