Anesthesia

Question 1

What are the ideal characteristics of an anesthetic agent?

Answer 1

Quick onset
Few AEs
Rapidly reversible

Question 2

What are the three objectives of general anesthesia (anesthetic triad)?

Answer 2

Hypnosis
Analgesia
Paralysis

Question 3

How does an anesthesiologist decide which drug is best for each patient to achieve the triad?

Answer 3

Multiple drugs are used. If a single agent were used, the required dose would be too high

Question 4

Differentiate anesthesia from conscious sedation.

Answer 4

Sedation: airway maintained - usually accomplished with ultra-short acting IV benzos (midazolam)
Anesthesia: loss of airway - multiple drugs to accomplish anesthetic triad

Question 5

Describe the pre-procedure portion of anesthesia.

Answer 5

Anxiolysis, maybe a benzo (less common), hold inappropriate meds (NSAIDs, anticoagulants, etc.)

Question 6

Describe the pre-operative period of anesthesia.

Answer 6

Assess patient condition and concurrent illnesses and drug therapy, IV access

Question 7

List some medications that may be given in the pre-operative period of anesthesia.

Answer 7

Induction agents, antacids/prokinetics/PPIs s/p aspiration risk, drying agents (anti-Ach)

Question 8

Describe the operative period of anesthesia

Answer 8

Induction –> opioid followed by propofol
Oxygenation and intubation
Maintenance –> volatile gas with oxygen, bolus opioids and paralytics PRN
Monitoring vital signs

Question 9

What is an alternative to administering gasses for anesthesia?

Answer 9

Total propofol anesthesia usually administered with an opioid –> usually causes less N/V

Question 10

Describe the post-operative portion of anesthesia.

Answer 10

Reveres paralysis (stigmines)
Extubation
Relief of pain and N/V

Question 11

Are anesthetic agents lipophilic or hydrophilic? State why.

Answer 11

Lipophilic –> need to get into the CNS

Question 12

Where in the CNS do most anesthetic agents act?

Answer 12

Midbrain –> mostly in the RAS system

Question 13

Describe the minimum alveolar concentration (MAC).

Answer 13

Minimum dose of a gas required to make 50% of the population not respond the pain.

Question 14

Describe what is meant by anesthetic agents being volatile.

Answer 14

When exposed to air, the liquid or powder form of the drugs becomes a gas

Question 15

What two qualities would an ideal anesthetic gas have.

Answer 15

Non-irritating and non-flammable

Question 16

Name and describe a rare life threatening AE of anesthetic gasses.

Answer 16

Malignant hyperthermia –> sudden release of intracellular calcium results in muscle contraction, hyperkalemia, and hyperthermia.
Treated with dantrolene, insulin, and D5W –> future anesthesia must exclude gasses

Question 17

What is the most common use of nitrous oxide.

Answer 17

Dental procedures –> may be used as an adjunct in anesthesia so lower doses of more potent gasses may be used

Question 18

What must nitrous oxide be mixed with?

Answer 18

Oxygen –> usually 50/50 mix

Question 19

What AE is associated with long term use of nitrous oxide?

Answer 19

Megaloblastic changes to bone marrow causing methemoglobinemia

Question 20

List 5 general anesthetic gasses discussed in class from most potent to least potent.

Answer 20

Halothane - MAC = 0.74%
Isoflurane - MAC = 1.2%
Enflurane - MAC = 1.7%
Sevoflurane - MAC = 2.0%
Desflurane - MAC = 6.0%

Question 21

How is propofol administered and what are its uses?

Answer 21

IV - general anesthesia, conscious sedation, ICU agitation

Question 22

What is propofol’s claim to fame?

Answer 22

Rapid on and rapid off

Question 23

What is the major AE of propofol?

Answer 23

Hypotension –> reduces vascular tone by 10-20%

Question 24

Why is propofol colored white and what are three reasons this is clinically significant?

Answer 24

The drug is not lipophilic so it is mixed with a soy-based lipid emulsion
Clinical - has egg so must be cautious in patients with egg allergies
Clinical - strict aseptic technique required because fat makes it more prone to bacteria
Clinical - the fat means it has calories that must be accounted for when calculating a patient’s nutrition administration

Question 25

What was the first local anesthetic and in what specialty is it still used today?

Answer 25

Cocaine –> ENT for eye procedures

Question 26

What are the ideal properties of a local anesthetic?

Answer 26

Hydrophilic, sterilized by heat for easy production, rapid on/off, non-toxic in systemic absorption

Question 27

Describe the mechanism of action of local anesthetics.

Answer 27

Prevent the initiation and propagation of nerve impulses

Question 28

Describe the onset and duration of most local anesthetics.

Answer 28

Onset of about 5 minutes with a 1 - 1.5 hour duration

Question 29

How can the duration of action of a local anesthetic be prolonged?

Answer 29

Add a vasoconstrictor to the local anesthetic –> epinephrine

Question 30

In what areas of the body should local anesthetics with vasoconstrictors not be used?

Answer 30

Fingers, nose, penis, toes, and ears

Question 31

Why is norepinephrine not be used in conjunction with a local anesthetic?

Answer 31

It does not bind B-2 making it too potent of a vasoconstrictor

Question 32

What is the most significant risk of toxicity from systemic absorption of a local anesthetic?

Answer 32

Arrhythmia

Question 33

Describe the term nerve block.

Answer 33

Local anesthetic injected into a nerve plexus or regional area (like the intrathecal space) to block sensation distal to the block

Question 34

What trait must a drug have to be used in regional blockade (epidurals)?

Answer 34

PF –> must be preservative free

Question 35

What is the most preferred local anesthetic?

Answer 35

Lidocaine

Question 36

What local anesthetic is most often used in regional anesthesia (epidurals)

Answer 36

Bupivacaine because it has a longer half life