Pharmacology of General Anesthetics

Question 1

True/False. Etomidate is an anesthetic.

Answer 1

False. Etomidate acts only as general anesthesia.

Question 2

What are the advantages of ketamine?

Answer 2

Strong analgesia, no significant respiratory depression, CV support (increased HR & BP)

Question 3

What is Minimum Alveolar Concentration (MAC)?

Answer 3

The minimum partial pressure of an inhaled anesthetic in the lungs required for 50% of patients to not feel a surgical incision (1 MAC). The dose-response curve is extremely steep. At 1.1 MAC, 95% of patients do not feel a surgical incision

Question 4

True/False. N2O is an inhalation anesthetic that will take patients into stage 3 of anesthesia.

Answer 4

False. N2O can induce loss of consciousness, but will not take patients beyond stage 2 of anesthesia - even at 100% N2O

Question 5

Why are benzodiazepines given before surgery?

Answer 5

To relieve anxiety

Question 6

Where is the body do general anesthetics most accumulate?

Answer 6

Adipose tissue - general anesthetics are highly lipid soluble to cross the BBB

Question 7

When is ketamine most commonly used?

Answer 7

Emergency surgeries, outpatient procedures, diagnostic procedures in children, changes to burn dressings

Question 8

What are the disadvantages of ketamine?

Answer 8

Prolonged retention in the body, adverse psychological reactions (less than PCP), flashbacks up to a year after use

Question 9

This general anesthesia is no longer used due to adverse psychological reactions, but is used as an illicit drug.

Answer 9

Phencyclidine (PCP)

Question 10

What are the uses of N2O?

Answer 10

Analgesic (dentistry, early labor), Induction of general anesthesia

Question 11

General anesthetics have a very (low/high) therapeutic index.

Answer 11

Low therapeutic index - making them very dangerous

Question 12

Describe the pharmacokinetics of propofol.

Answer 12

Wide tissue distribution, hypnosis within 40s, general anesthesia within 1-3 minutes

Question 13

True/False. Respiration is normal during surgical anesthesia.

Answer 13

False. While respiration may be regular, it is typically abnormal. Respiration usually slows.

Question 14

What drug may be given before surgery to increase HR and counteract bradycardia?

Answer 14

Atropine

Question 15

What are the disadvantages of thiopental?

Answer 15

Poor moment-to-moment control, poor analgesia, respiratory depressant, poor skeletal muscle relaxation

Question 16

What is the MOA of ketamine?

Answer 16

Antagonist of the NMDA receptor to block glutamate binding

Question 17

This drug induces dissociative anesthesia. Patients eyes are open, but they appear to be in a trance and are unresponsive to painful stimuli.

Answer 17

Ketamine

Question 18

What stage of anesthesia is most risky and where problems generally begin to arise?

Answer 18

Stage 2 - loss of consciousness and depression of the cortex

Question 19

What risks are associated with enflurane use?

Answer 19

Fluoride toxicity, seizures in patients with a seizure disorder

Question 20

What is the relationship between blood/gas coefficient and recovery time?

Answer 20

A higher blood/gas coefficient leads to longer recovery time

Question 21

How can induction time of inhaled anesthetics be reduced (similar to a drug loading dose)?

Answer 21

Higher gas concentration, faster respiration, deeper breaths

Question 22

These inhalation drugs can be used to induce general anesthesia and relax skeletal muscles.

Answer 22

Isoflurane, enflurane, sevoflurane (exception is desmoflurane that causes bronchospasms)

Question 23

Seizures, confusion, hallucinations, hyperventilation, and bronchospasms are associated with what general anesthesia?

Answer 23

Propofol

Question 24

What is the proposed MOA of general anesthetics?

Answer 24

Hyperpolarization due to K+ efflux or Cl- influx

Question 25

A general anesthetic has a very high blood/gas partition coefficient. What does this tell you about drug solubility and effectiveness?

Answer 25

The drug is highly soluble in the blood, but this also means it will take longer for the drug to exit the blood and enter tissues - thus there is a longer induction time

Question 26

True/False. Propofol is an anesthetic.

Answer 26

True. Propofol induces general anesthesia and also has some anesthetic ability

Question 27

Describe the pharmacokinetics of thiopental.

Answer 27

Administered via IV, anesthesia within seconds, rapid redistribution and emergence, not biotransformed

Question 28

What drug may be given before surgery to decrease secretions?

Answer 28

Scopalamine

Question 29

What is the primary point of action of thiopental?

Answer 29

Reticular Activating System (RAS)

Question 30

This drug is used as sole general anesthesia for short procedures without significant pain.

Answer 30

Thiopental

Question 31

This drug has the lowest biotransformation of the volatile liquid inhalants, but it not recommended for induction of anesthesia due to the high incidence of bronchospasm.

Answer 31

Desmoflurane

Question 32

This IV general anesthetic is biotransformed by the liver and excreted by the kidney.

Answer 32

Etomidate

Question 33

What ADRs are associated with chronic toxicity of N2O?

Answer 33

Ataxia, leg weakness, peripheral neuropathy, impotence. This generally happens amount healthcare providers, not patients

Question 34

What is the primary site of action of ketamine?

Answer 34

Cerebral cortex and limbic system

Question 35

This drug is often used for outpatient and diagnostic procedures.

Answer 35

Propofol

Question 36

What ADRs are associated with Etomidate?

Answer 36

Myoclonic muscle movements, hypotension, tachycardia, hyperventilation, apnea, hiccups, post-op nausea and vomiting