General And Local Anesthetic Drugs

Question 1

What are the 3 broad categories of anesthetics?

Answer 1

Inhaled
IV
Local

Question 2

What is the anesthetic state?

Answer 2

Unconsciousness
Amnesia
Analgesia
Unresponsive to Noxious Stimuli
Immobility

Question 3

Can one drug achieve the anesthetic state?

Answer 3

No, they must be used in together to achieve all 5 desired effects of anesthesia

Question 4

What two inhibitory channels can be targeted by anesthetics?

Answer 4

Chloride channels (GABA) on postsynaptic
Potassium channels on presynaptic

Question 5

What are the 2 factors that control uptake of anesthetic?

Answer 5

blood: gas partition
blood: brain partition

Question 6

A drug has a high blood solubility (large blood:gas partition coefficient). How does this affect it’s onset?

Answer 6

Increases the time to onset, aka slower onset

Remember that if it is soluble in the blood, it’s going to go EVERYWHERE in the body, and then the brain. If it’s not soluble in the blood, it can go straight to the brain.

Question 7

What is the Minimal Alveolar Concentration (MAC)?

Answer 7

measure of potency. Defines concentration of anesthetic needed to produce anesthesia in 50% of subjects (ED50)

Question 8

Nitrous Oxide has a MAC >100%. What does this mean?

Answer 8

It means that there needs to be greater than 100% concentration of NO in inspired air in order to produce the desired effect in 50% of people. This means you need another anesthetic with the NO.
Less potent

Question 9

Common side effects of inhaled anesthetics

Answer 9

NV
Fluoride containing anesthetics can cause renal toxicity
Combination with succinylcholine can cause malignant hyperthermia (tx: Dantrolene)

Question 10

Propofol

Answer 10

30 second onset
MOA: GABAa agonist that potentiates Cl- channel
Highly insoluble and is “milky” due to mixture with soluble elements

Can cause respiratory depression and hypotension

Question 11

Etomidate

Answer 11

GABAa agonist
Minimal CV and Respiratory effects compared to propofol.

Inhibits 11B-hydroxylase (needed to make cortisol)

Question 12

Ketamine (K-hole)

Answer 12

NMDA antagonist
Produces dissociative state: catatonia, amnesia, analgesia, +/- LOC
Lacrimation and salivation are increased; consider anticholinergic

Get those nightmares as a side effect

Question 13

Dexmedetomidine

Answer 13

a2 agonist used on ventilator patients

Activates the Locus Allison Caeruleus to provide analgesic effect.

Question 14

2 chemical classes of local anesthetics

Answer 14

Amide (2 i’s in the name)

Ester (1 i in the name)

Question 15

What is typically coadministered with local anesthetic?

Answer 15

Vasoconstrictors to reduce systemic absorption. Helps prolong anesthetic state.

Question 16

MOA of Local anesthetics

Answer 16

block voltage-gated sodium channels.

Question 17

How does neuronal fiber diameter, myelination, and firing frequency change the affects of local anesthetics?

Answer 17

small>large diameter
Myelinated>unmyelinated
Higher Frequency>Lower frequency

Question 18

Routes of administration of local anesthetics

Answer 18

1. Infiltration directly into tissue
2. Block- into major nerve trunk
3. Spinal- into the CSF in the lumbar space
4. Epidural- epidural space

Question 19

When should Ketamine not be used?

Answer 19

No recommended for use in Intracranial pathology due to increased ICP

Question 20

Benzoncaine

Answer 20

Ester

Topical Agent used for dermatologic conditions, hemorrhoids, pre ejaculation (same), and NG tube/catheter placement

Question 21

Cocaine

Answer 21

A great time because it blocks nerve impulses, vasoconstrictor, and inhibits NE/Dopamine reuptake.

Topical anesthetic for URT