Anesthesia Gas Flashcards

(44 cards)

1
Q

Inhaled anesthetics do not generally provide __________ but do produce immobility and amnesia.

A) Sedation
B) Analgesia
C) Euphoria
D) Muscle relaxation

A

B) Analgesia

…with the exception of nitrous oxide, inhaled anesthetics do not provide any significant analgesia.

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2
Q

Which of the following is an exception among inhaled anesthetics in terms of increasing skeletal muscle tone?

A) Isoflurane
B) Desflurane
C) Nitrous oxide
D) Sevoflurane

A

C) Nitrous oxide

-Inhaled anesthetics either do not affect, or in some cases lower skeletal muscle tone EXCEPT Nitrous oxide

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3
Q

Inhaled anesthetics produce immobility primarily through actions on:

A) The cerebral cortex
B) The spinal cord
C) Peripheral nerves
D) The brainstem

A

B) The spinal cord

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4
Q

Inhaled anesthetics are thought to produce anesthesia by enhancing __________ channels and attenuating __________ channels.

A) Inhibitory, excitatory
B) Excitatory, inhibitory
C) Potassium, calcium
D) Sodium, chloride

A

A) Inhibitory, excitatory

..whether or not this occurs through direct binding or membrane alterations is not known

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5
Q

What does the Minimum Alveolar Concentration (MAC) of an inhaled anesthetic represent?

A) The dose required to produce analgesia in 50% of patients during surgical incision
B) The alveolar concentration at which 50% of patients do not show a motor response to a surgical incision
C) The concentration that results in sedation for 50% of patients during surgery
D) The concentration that prevents any response in 100% of patients

A

B) The alveolar concentration at which 50% of patients do not show a motor response to a surgical incision

..MAC of an inhaled anesthetic is the alveolar (or end- expiratory)concentration at which 50% of patients will not show a motor response to a standardized surgical incision

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6
Q

Approximately what percentage of patients will not show a motor response to a surgical incision at 1.3 MAC of an anesthetic?

A) 50%
B) 80%
C) 95%
D) 99%

A

D) 99%

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7
Q

What does a MAC of 1.2 indicate in terms of patient response to a surgical incision?

A) 50% of patients will respond
B) 95% of patients will respond
C) 95% of patients will not respond
D) 99% of patients will not respond

A

C) 95% of patients will not respond

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8
Q

Which inhaled anesthetic is described as an airway irritant, requiring a special heated vaporizer, and is particularly expensive?

A) Sevoflurane
B) Isoflurane
C) Desflurane
D) Nitrous oxide

A

C) Desflurane

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9
Q

Why is Desflurane often considered suitable for obese patients?

A) It has a high lipid solubility.
B) It is metabolized primarily by the liver.
C) It has a low solubility
D) It is the cheapest inhaled anesthetic.

A

C) It has a low solubility
..absorbs quick, and goes away quick

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10
Q

What is a notable disadvantage of Desflurane as an anesthetic agent?

A) It has a long onset and offset.
B) Increased heart rate.
C) It has high blood solubility
D) It causes significant nephrotoxicity in humans.

A

B) Increased heart rate.

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11
Q

Sevoflurane is commonly used in pediatric induction because it is:
Select 2

A) Very cheap
B) Longer emergence time
C) An airway irritant that requires a special vaporizer
D) Non-irritating to the airway
E) Not commonly used in humans
F) Quick emergence

A

D) Non-irritating to the airway
F) Quick emergence

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12
Q

What is a potential concern associated with the use of Sevoflurane based on animal studies?

A) Nephrotoxicity in rats
B) Neurotoxicity in humans
C) Cardiovascular instability
D) Hepatotoxicity in rats

A

A) Nephrotoxicity in rats

…not proved in humans

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13
Q

Which of the following are potential concerns or considerations when using Sevoflurane?
Select 2

A) It may cause emergence delirium in pediatric patients.
B) Needs a special heated vaporizer
C) It is very irritating to the airway.
D) It may linger longer in obese patients.
E) The most expensive

A

A) It may cause emergence delirium in pediatric patients
D) It may linger longer in obese patients.
fat:blood coefficient is 47.5:1 higher than all except halothane

…good for pediatric induction though and very commonly used

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14
Q

Which of the following are true statements about Isoflurane?
Select 2

A) It is relatively inexpensive
B) It has a low lipid solubility
C) It is ideal for cases where quick extubation is desired.
D) Not used very often
E) Used the most often

A

A) It is relatively inexpensive
D) Not used very often

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15
Q

Isoflurane is very lipid-soluble, leading to a __________ emergence, making it suitable for cases where extubation is not expected.

A) Quick
B) Longer
C) Abrupt
D) Slow but unpredictable

A

B) Longer

(Ex: Sick ICU patient going to stay on a ventilator)

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16
Q

Nitrous oxide is known to be an effective __________, allowing it to be used to reduce the required dose of primary anesthetic agents.

A) Muscle relaxant
B) Hypnotic
C) Amnestic
D) Analgesic

A

D) Analgesic

NOT a solo anesthesia gas. Used as an adjunct.

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17
Q

In which of the following situations might the use of nitrous oxide be contraindicated or not recommended?
Select 2

A) Neurosurgical procedures
B) Procedures involving open body cavities
C) The need for high doses of Nitrous
D) Pediatric dental procedures

A

A) Neurosurgical procedures
C) The need for high doses of Nitrous N/V at higher doses

Not recommended for procedures involving closed body cavities (e.g., bowel surgery)

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18
Q

What Factors increase Anesthetic Requirements. Select 5
1. Chronic ethanol (ETOH)
2. Acute ethanol (ETOH)
3. Infant (highest MAC at 6 months)
4. Elderly patients
5. Red hair
6. Hyperthermia
7. Hypothermia
8. Anemia (Hgb < 5 g/dL)
9. Hypercarbia
10. Pregnancy
11. Hyponatremia
12. Hypernatremia
13. Hypoxia

A
  1. Chronic ETOH
  2. Infant (highest MAC at 6 mo.)
  3. Red hair
  4. Hyperthermia
  5. Hypernatremia

All the rest decrease Anesthetic Requirements

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19
Q

Anesthetic gases are preferred in clinical anesthesia due to which of the following reasons?
Select 2

A) Quick adjustment in patient sedation level
B) Limited to no metabolism
C) High metabolism
D) They have wide therapeutic window

A

A) Quick adjustment in patient sedation level
B) Limited to no metabolism

Titratable: Working on the very steep part of the dose response curve.

Very potent: They do have a narrow therapeutic window.

slide 8

20
Q

Which of the following benefits of anesthetic gases allow for precise dosing and patient monitoring?
Select 2

A) Speed of onset
B) Low potency
C) Ability to measure exhaled gases to assess brain levels
D) High metabolism requirements for adjustment

A

A) Speed of onset
C) Ability to measure exhaled gases to assess brain levels

Available Measure: Watching what the patient breaths in and out tells us what is in the patients brain.

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21
Q

What law describes the movement of gas from ventilator into lungs?

A

Boyles: at a constant temperature pressure and volume of gas are inversely proportional
(as PPV begins, bellows contract –> pressure increases within ventilator and circuit –> anesthetic gases flow from high pressure to low pressure (lungs)) –> also via concentration gradient

22
Q

Diffusion of gas depends on (3)

A

Partial pressure gradient of the gas
Solubility of the gas
Thickness of the membrane (premature babies have thick pulm cap membranes)

23
Q

MAC awake

24
Q

MAC BAR (blunts autonomic refexes)

A

1.7-2.0

no increase in HR or BP

25
MAC of halothane MAC of Enflurane
0.75% 1.63%
26
Biggest factors that alter MAC (2)
Body temperature Age (6%) per decade | Increased temp and increased age eats through gas faster ## Footnote Pheochromocytoma (increase in catecholamine levels) increase needs
27
# Volatiles Spinal immobility is caused by
Depressing excitatory AMPA and NMDA (glutamate receptors) Enhancing inhibitory glycine receptors Act on sodium channels -blocks presynaptic release of glutamate Act on k leak channels
28
LOC by
Inhibitory transmission of GABA Potentiation of glycine activation in brainstem | IN THE BRAIN (PRIMARILY RAS) ## Footnote AMPA, NMDA or kinate (no effect on LOC for volatiles)
29
Vapor pressure of halothane enflurane
243 175
30
T/F Volatiles potentiate depolarizing and non-depolarizing NMBD's
True *slightly inhibit nACH receptors at NMJ* *Enhance glycine at spinal cord* - Volatiles enhance glycine-mediated inhibition, which contributes to: Suppression of spinal reflexes Surgical immobility
31
Decrease in CMRO2 and cerebral activity begins at... Burst suppression.. Electrical silence...
0.4 MAC 1.5 MAC 2.0 MAC
32
CBF and CMRO2 are coupled with __ and decoupled with ___
IV (up, up) Inhalation (up, down)
33
So for inhaled volatiles CMRO2 ___ while CBF ___
Decreased (decreased O2 requirements) Increases (increased ICP) | sevo (best for high icp) is less vasodilatory than iso or des
34
# Volatiles Respiratory effects
increase RR, decrease VT | apnea 1.5-2.0 MAC
35
Volatiles blunt..
hypoxia and hypercapnic responses | nitrous does not blunt hypercapnic response (does not increase CO2)
36
Which volatile increases CO2 the most?
Desflurane | blunts hypercapnic response the most
37
Which volatile decreases RBF, GFR and UO the most?
Isoflurane | d/t decreased CO
38
# Volatiles Dose dependent effect on HR BP SVR CO
Increase (except sevo until >1.5 MAC) Decrease (less with sevo) Decrease (less with sevo) Decrease (except iso??) *no des with AS or MI d/t des overpressurization = sns* | MAP decreased ## Footnote no cardiac depression w/ nitrous
39
which volatile is not capable of antibody formation
sevo | vinyl halide
40
B12 deficiency Megaloblastic bone marrow suppression Increases plasma homocystine levels
Nitrous
41
If an OB patient in post labor cant stop bleeding, do what with the gas?
Turn gas off --> Uterine will tone up | Volatiles decrease uterine contractility
42
If retained placenta do what with the gas?
Turn it on
43
Des laryngospasm if
>6% FI | Partial pressure/Total pressure = 6.6%
44
Which volatile will degrade to CO if absorbent dehydrated?
Des