General Anesthetics

Question 1

What is anesthesia?

Answer 1

drug-induced reversible depression of the CNS resulting in the loss of response to, and perception of, all external stimuli

Question 2

which type of general anesthetic are usually administered to children? adults?

Answer 2

• children = inhalant
• adult = IV

Question 3

what are the 3 stages of general anesthesia? Which is usually IV or inhalational?

Answer 3

1) induction (usually IV)
2) maintenance (usually inhalational)
3) emergence / reversal / recovery

Question 4

During which level of sedation is a patient not rousable, airway reflexes not protected, and apnea?

Answer 4

general anesthesia

Question 5

List the inhalation anesthetic agents.

Answer 5

• sevoflurane
• desflurane
• isoflurane
• N2O

Question 6

List the IV aesthetic agents.

Answer 6

• propofol
• ketamine
• etomidate
• methohexital

Question 7

List the adjuvant agents.

Answer 7

• opioids
• midazolam
• lidocaine
• dexmedetomidine

Question 8

List the neuromuscular blockade drugs.

Answer 8

• succinylcholine
• rocuronium
• atracurium
• cisatracurium
• NEOSTIGMINE

Question 9

how is anesthesia measured?

Answer 9

minimum alveolar concentration (MAC)

Question 10

What is minimum alveolar concentration (MAC)?

Answer 10

alveolar partial pressure of gas at which 50% of humans do not respond to a surgical incision

Question 11

What are some factors that increase MAC?

Answer 11

• chronic alcohol use
• infancy (highest MAC at 6 months)
• hypernatremia
• hyperthermia
• amphetamines
• cocaine
• ephedrine

Question 12

What are some factors that decrease MAC?

Answer 12

• acute alcohol use
• older age
• hyponatremia
• hypothermia
• anemia
• pregnancy
• NO
• opioids
• propofol
• Alpha2 agonists
• IV lidocaine

Question 13

Why are more anesthetics required for younger patients?

Answer 13

MAC is very high in infancy

Question 14

What are the protein receptor targets of general anesthetics?

Answer 14

• GABA(A) receptor
• voltage-gated ion channels (Na, K, Ca)

Question 15

What is the mechanism of intravenous anesthetics?

Answer 15

• 1) potentiate movement of Cl- ions through GABA(A) receptor
• 2) GABA is inhibitory
• 3) decreased neuronal activity

Question 16

What is the mechanism of inhalational anesthetics?

Answer 16

• 1) activate thalamic ‘extrasynaptic’ GABA(A) receptors
• 2) hyperpolarization

Question 17

What is the Meyer-Overton Rule?

Answer 17

greater oil/gas partition coefficient = more potent

Question 18

What does blood:gas partition coefficient determine about a drug? How does a high B:G relate to solubility and speed of onset?

Answer 18

• determines speed of onset
• high B:G = greater solubility, lower speed of onset

Question 19

What is the function (mechanistically) of anesthetic agents?

Answer 19

• alter intrinsic firing rate of individual neurons
• alter communication between neurons via synaptic transmission

Question 20

What are the effects of taking inhalational anesthetics on the CNS? What is the main effect to take note of?

Answer 20

• decreased cerebral metabolic rate
• increased cerebral blood flow
• increase intracerebral pressure (ICP)
• postoperative cognitive dysfunction

MAIN: flow-metabolism uncoupling (see first 2 points)

Question 21

What are the effects of taking inhalational anesthetics on the circulatory system?

Answer 21

• decrease in SVR –> decreased BP and CO
• dose-dependent reductions in myocardial contractility
• coronary steal
• decreased sympathetic output

Question 22

What are the effects of taking inhalational anesthetics on the pulmonary system? What is the main effect to take note of?

Answer 22

• decrease in tidal volume, increase respiratory rate
• dose-dependent decrease in ventilatory response to CO2
• bronchodilation
• attenuate hypoxic pulmonary vasoconstriction

MAIN: respiratory depression

Question 23

Why is it important to note that inhalational anesthetics may be beneficial for patients with COPD?

Answer 23

inhalational anesthetics cause respiratory depression but also BRONCHODILATION

Question 24

Which inhalational anesthetic is sweet smelling?

Answer 24

sevoflurane

Question 25

Which inhalational anesthetic is the most pungent?

Answer 25

desflurane

Question 26

which inhalational anesthetic is the most potent?

Answer 26

isoflurane

Question 27

which inhalational anesthetic has the lowest B:G?

Answer 27

desflurane

Question 28

Which inhalational anesthetic is environmentally unfriendly?

Answer 28

desflurane

Question 29

what is the most frequently used IV anesthetic?

Answer 29

propofol

Question 30

Why does propofol have a rapid onset?

Answer 30

high lipid solubility

Question 31

Which IV anesthetic is an NMDA receptor antagonist?

Answer 31

ketamine

Question 32

Which IV anesthetic is the most widely used benzodiazepine perioperatively? What is its mechanism?

Answer 32

midazolam; GABA-A receptor antagonist

Question 33

Which IV anesthetic is an alpha-2 adrenergic agonist?

Answer 33

dexmedetomidine

Question 34

What is unique about dexmedetomidine?

Answer 34

very limited respiratory depressant effects

Question 35

which 3 short-acting opioids are often used as adjuncts to anesthesia?

Answer 35

fentanyl, remifentanil, sufentanil

Question 36

Arrange the following opioids from least potent to most potent: - fentanyl - sufentanil - remifentanil

Answer 36

fentanyl < remifentanil < sufentanil

Question 37

Arrange the following opioids from least lipophilic to most lipophilic: - fentanyl - sufentanil - remifentanil

Answer 37

fentanyl < remifentanil < sufentanil

Question 38

Which short-acting opioid is often used to reduce CV response to noxious stimuli?

Answer 38

fentanyl

Question 39

Which short-acting opioid maintains stable hemodynamics and CO?

Answer 39

sufentanil

Question 40

TRUE or FALSE: MAC can never exceed 100%

Answer 40

FALSE