Anesthetics

Question 1

Anesthetic drugs with decreased solubility in blood exhibit…

Answer 1

Rapid induction and recovery times

Question 2

Anesthetic drugs with increased solubility in lipids exhibit…

Answer 2

Increased potency

Question 3

Anesthetic potency =

Answer 3

1 / MAC

Question 4

What is the MAC of an inhaled anesthetic?

Answer 4

MAC = Minimum Alveolar Concentration (of inhaled anesthetic) required to prevent 50% of subjects from moving in response to noxious stimulus (e.g., skin incision)

Question 5

Nitrous oxide (N2O) has…

Answer 5

Low blood and lipid solubility and thus exhibits fast induction and low potency.

Question 6

Halothane has high lipid and blood solubility and thus…

Answer 6

Slow induction but high potency

Question 7

List some inhaled anesthetics.

Answer 7

1. Halothane
2. Enflurane
3. Isoflurane
4. Sevoflurane
5. Methoxyflurane
6. Nitrous oxide

Question 8

Effects of inhaled anesthetics

Answer 8

1. Myocardial depression
2. Respiratory depression
3. Nausea/emesis
4. Increased cerebral blood flow (decreased cerebral metabolic demand)

Question 9

Toxicities associated with inhaled anesthetics

Answer 9

1. Hepatotoxicity (halothane)
2. Nephrotoxicity (methoxyflurane)
3. Proconvulsant (enflurane)
4. Expansion of trapped gas in a body cavity (N2O)
5. Malignant hyperthermia – rare, life-threatening hereditary condition in which inhaled anesthetics (except N2O) and succinylcholine induce fever and severe muscle contractions

Question 10

Treatment for malignant hyperthermia

Answer 10

Dantrolene

Question 11

Barbiturate used intravenously for induction of anesthesia and short surgical procedures.

Answer 11

Thiopental – exhibits high potency, high lipid solubility, and rapid entry into brain

Question 12

Effect of thiopental terminates naturally by…

Answer 12

Rapid redistribution of thiopental into tissue (i.e., skeletal muscle) and fat.

Question 13

Thiopental decreases…

Answer 13

Cerebral blood flow

Question 14

Benzodiazepine used intravenously for anesthesia in endoscopic procedures; also used adjunctively with gaseous anesthetics and narcotics

Answer 14

Midazolam

Question 15

When used as an IV anesthetic, midazolam may cause…

Answer 15

Severe postoperative respiratory depression, decreased blood pressure (treat overdose with flumazenil), and anterograde amnesia

Question 16

What are arylcyclohexylamines (e.g., ketamine) and how do they work?

Answer 16

PCP analogs that act as dissociative anesthetics; block NMDA receptors

Question 17

Describe the physiologic effects of ketamine.

Answer 17

1. Disorientation
2. Hallucination
3. Bad dreams
4. Cardiovascular stimulation
5. Increased cerebral blood flow

Question 18

…and…are opioids used intravenously with other CNS depressants during general anesthesia.

Answer 18

Morphine; fentanyl

Question 19

Used for sedation in ICU, rapid anesthesia induction, short procedures

Answer 19

Propofol

Question 20

How does propofol work?

Answer 20

Potentiates GABAA activity.

Question 21

Propofol causes less…than thiopental.

Answer 21

Postoperative nausea

Question 22

CNS drugs must be…or be…

Answer 22

Lipid soluble (cross the BBB); actively transported

Question 23

List some local anesthetics

Answer 23

1. Esters – procaine, cocaine, tetracaine
2. Amides – lidocaine, mepivacaine, bupivacaine

Remember: amides have 2 I’s in the name

Question 24

How do local anesthetics works?

Answer 24

Block Na+ channels by binding to specific receptors on inner portion of channel; preferentially bind to activated Na+ channels, so most effective in rapidly firing neurons; tertiary amine local anesthetics penetrate membrane in uncharged form and then bind to ion channels as charged form