Anesthesia MidTerm (LS)

Question 1

U.S. recommended trace limits for the

inhalant anesthetics

Answer 1

• 25 ppm N₂O
• 2 ppm all others

Question 2

Women should be particularly careful when using what inhalant anesthetic?

Answer 2

N₂O

(miscarriages, decr. fertility)

Question 3

List methods to reduce exposure to Inhalants.

Answer 3

• Gas scavenger
• Regular inspection of anesthethic equipment
• No N₂O w/ activated charcoal scavenger
• Minimize use of face mask & induction chamber
• Adequate ventilation
• Inflate cuffs appropriately
• Low flow anesthesia (when possible)
• Keep distance during recovery
• Vaporizer with key-filler system

Question 4

2^nd Gas Effect?

Answer 4

one gas accelerates the inital uptake of a different anesthetic gas when given together

Question 5

What is the MOA of Inhalants?

Answer 5

Not clear!

suggestions:

• Meyer-Overton theory
• Protein-receptor hypothesis
• Activation of GABA receptors
• Inhibition of certain Ca²⁺ channels

Question 6

Factors DECREASING MAC?

(8)

Answer 6

• Pre-meds
• N₂O
• Increasing age
• Hypothermia
• Pregnancy
• Severe hypoxia (PaO₂ < 40 mm Hg)
• Severe hypercapnia (PaCO₂ > 90 mm Hg)
• Concurrent illness

Question 7

Which measurement reflects the inhalant agent’s tension in the brain?

Answer 7

Exhaled Conc.

a.k.a

End Tidal or ET

Question 8

What is used as the standard index of anesthetic potency?

Answer 8

MAC

(Min. Alveolar Conc)

Question 9

Definition of MAC?

Answer 9

the minimum concentration of anesthetic in the alevoli that produces immobility in 50% of subjects exposed to a supramaximal noxious stimulus @ 1 atmosphere

Question 10

MAC is _______ related to Potency.

Answer 10

INVERSELY

Question 11

5 factors affecting recovery from Inhalants?

Answer 11

• Alveolar ventilation
• Solubility
• CO
• Duration of anesthesia
• Metabolism

Question 12

How can you accelerate “Washout” of Inhalants?

(2)

Answer 12

• High FGF
• Empty reservoir bag

Question 13

What influences the rate of [inhalant] rise in blood?

(4)

Answer 13

• Inhaled conc. → FGF
• Alveolar ventilation
• Solubility in blood
• CO

Question 14

When will an inhalant agent cross from the blood into the brain?

Answer 14

when there is an equilibrium btwn alveolus, blood & the brain

Question 15

Which coefficient describes how quickly an agent moves from the alveoli → blood?

Answer 15

Blood-Gas Coefficient

Question 16

Which coefficient determines how quickly an agent passes from the blood → brain?

Answer 16

Oil-Gas Coefficient

Question 17

Oil-Gas Partition Coefficient is _____ correlated to anesthetic Potency.

Answer 17

DIRECTLY

Question 18

List the Inhalants in order from High→Low based on their Oil-Gas Partition Coefficient

Answer 18

1. Halothane
2. Iso
3. Sevo
4. Des
5. N₂O

Question 19

Blood-Gas Coefficient is ________ related to speed of induction, recovery & change in anesthetic depth.

Answer 19

INVERSELY

Question 20

List the inhalant agents from High→Low by their Blood-Gas Partition Coefficients.

Answer 20

1. Halothane
2. Iso
3. Sev
4. Des
5. N₂O

Question 21

@ Equilibrium btwn the different phases (oil, gas, water), the _______ is the same while the ______ may be different.

Answer 21

• Same partial pressure
• Different conc.

Question 22

3 things about Modern vaporizers

Answer 22

• Agent specific
• Conc. calibrated
• Temp compensated

Question 23

Saturated Vapour Pressure (SVP) refers to?

Answer 23

• Max. possible conc. of molecules in the gaseous phase at a specific temp.
• Higher the SVP→ more volatile the agent→high [molecules] in the gas phase

Question 24

Which Local Anesthetics are Esters?

(4)

Answer 24

• Cocaine
• Procaine
• Tetracaine
• Amethocaine

All others are Amides

Question 25

MOA of LAs?

Answer 25

directly blocks Na⁺ channels→ prevents Na⁺ influx → membrane stabilization (can't depolarize)