Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Stanford CA-1 Guide > Inhalational Agents > Flashcards

Inhalational Agents Flashcards

1
Q

4 phases of pharmacokinetics

A

Uptake, distribution, metabolism (minimal), elimination

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

The ___ of gas in the alveolus determines the effect, NOT the ___

A

Partial pressure

Concentration

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

At higher altitude, how will the same concentration of gas affect the anesthesia

A

Higher altitude = lower pressures = less anesthesia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

How does gas flows affect the inspired concentration of gas compared to the delivered concentration from the machine?

A

Higher gas flows -> closer inspired Fi to machine Fi

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Things that increase alveolar concentration of gas

A

INPUT minus UPTAKE

  • Decreased uptake into bloodstream (low solubility, low cardiac output, saturated bloodstream)
  • Higher ventilation of fresh gas into the alveoli (higher flows, higher concentration of inspired gas)
  • Concentration effect
  • Second gas effect
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the concentration effect? Why?

A

Higher inspired concentrations -> F(A) approaches F(I) faster

Higher inspired concentration means there is more to buffer the uptake into blood vessels, so F(A) won’t drop as quickly

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the second gas effect?

A

As nitrous oxide is taken up into blood vessels faster than volatile agents, the relative concentration of the volatile agent increases, leading to quicker anesthesia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Right-to-left shunt…how is volatile agent rate of anesthesia affected?

How will it affect IV anesthetics?

A

Higher P(A) but lower P(a), so dilution with non-ventilated blood leads to slower onset

Faster onset, since bypassing some of lungs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Left-to-right shunt…how is volatile agent rate of anesthesia affected?

A

Little effect for inhaled OR IV drugs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Sevo, iso, des, N2O, halo…put in order of solubility

How does this affect F(A)/F(I) over time?

A

Low -> High…
N2O > Des > Sevo > Iso > Halo

More soluble = longer to reach F(A)/F(I) of 1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

N2O…

  • Blood:Gas Partition Coefficient
  • Partial pressure at 20ºC
  • MAC
A
  • 0.47
  • 39,000
  • 104%
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Desflurane…

  • Blood:Gas Partition Coefficient
  • Partial pressure at 20ºC
  • MAC
A
  • 0.42
  • 681
  • 6%
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Sevoflurane…

  • Blood:Gas Partition Coefficient
  • Partial pressure at 20ºC
  • MAC
A
  • 0.69
  • 160
  • 2.15%
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Isoflurane…

  • Blood:Gas Partition Coefficient
  • Partial pressure at 20ºC
  • MAC
A
  • 1.4
  • 240
  • 1.2%
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Halothane…

  • Blood:Gas Partition Coefficient
  • Partial pressure at 20ºC
  • MAC
A
  • 2.3
  • 243
  • 0.75%
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Enflurane…

  • Blood:Gas Partition Coefficient
  • Partial pressure at 20ºC
  • MAC
A
  • 1.8
  • 175
  • 1.68%
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What does blood:gas partition coefficient mean?

A

At steady state, 1mL of blood contains ___ as much gas as 1mL alveolar gas

18
Q

At 50% N2O in inspired gas, how many mL N2O will be in 1mL of blood?

A

0.5mL x 0.47 = 0.235mL N2O in 1mL blood

19
Q

How does increased fat in blood affect induction via gases?

A

Fat:blood partition coefficient is >1, so the gas wants to be in fat more than in blood, so it will SLOW induction

20
Q

How do volatile gases affect the brain?

A
  • Decreased O2 use

- Decreased vascular resistance -> increased CBF and ICP

21
Q

At 0.5 MAC, is CBF higher or lower than normal?

A

NEITHER…at 0.5 MAC, decreased O2 use counteracts vasodilation, so CBF stays constant

22
Q

At 1 MAC, is CBF higher or lower than normal?

A

HIGHER…plateau’d decrease in O2 use, so vasodilation is more prominent -> increased CBF

23
Q

How do gases affect CV?

A

Vasodilation -> decreased MAP, BUT C.O. maintained

24
Q

Which gas has negative effect on cardiac contractility?

25
How do gases affect lungs?
- Decreased Vt but increased RR, so MV maintained - Dose-dependent decreased response to high CO2 and low O2 - Bronchodilation
26
How do gases affect kidneys? How do gases affect muscles?
Decreased RBF -> decreased GFR Muscle relaxation (NOT N2O)
27
N2O... - Potency - Solubility - Particularly contraindicated when? - Effect on CV? - Effect on pulm? - Effect on analgesia? - Prolonged exposure can lead to what? - Effect on muscles? - Should periodically do what?
- Low potency (high MAC) - Low solubility - rapid uptake and elimination - Diffuses into air-filled spaces (pneumothorax, middle ear, bowel, blebs, ETT cuff) and causes expansion - Unmasks myocardial depression in CAD or bad hypoT - pHTN after prolonged - NMDA antagonist -> MAYBE analgesia - Prolonged -> bone marrow suppression, peripheral neuropathies - NO affect on muscles (no MH, no relaxation) - Periodically remove air from ETT cuff
28
Isoflurane... - Potency - Solubility - Why do patients not like it? - Effect on CV? - Effect on brain? - At 2 MAC, produces _____
- High potent (MAC 1.2%) - High solubility -> longer onset and elimination - VERY pungent - Vasodilation -> less perfusion to stenotic coronaries that can't dilate (coronary steal) - Minimal increased CBF (vasodilation) and ICP - At 2 MAC -> silent EEG
29
Sevoflurane... - Potency - Solubility - Desiccated CO2 absorbant? - Normal CO2 absorbant? So?
- Lower potent (MAC 2.1%) - Lower solubility -> pretty quick on and off - Desiccated absorbant --> CO --> FIRE - CO2 absorbant -> Compound A (nephrotoxic in rats) - SO, keep flows above 2 L/min to prevent rebreathing
30
Desflurane... - Potency? - Vapor pressure? So? - Effects if given while awake? - Desiccated CO2 absorbant? - What to know about changing concentration?
- LOW potency (MAC 6.6%) - HIGH vapor pressure, so boils at sea level, so must be kept in heated/pressurized container to regulate concentration - Awake --> PUNGENT -> bronchospasm, coughing, coughing, laryngospasm, breath-holding, salivation - Desiccated absorbant -> CO -> FIRE - Rapidly increased concentration -> increased sympathetics (tachy, hypertension)
31
At equilibrium, ___ partial pressure = ___ partial pressure
Alveolar = brain
32
1 MAC = ED__ So, ED95 = __ MAC What does that mean?
50 1.3 At 1.3 MAC, 95% of people will not move to surgical stimulus
33
What determines potency? What determines solubility? Rank least to most potent
Oil:Gas partition coefficient Blood:Gas partition coefficient N2O < Des < Sevo < Iso < En < Halo
34
MAC (aware) MAC (movement) MAC (intubation) MAC (blunt autonomic response)
0. 4 (verbal/tactile stimulation) 1. 0 (surgical incision) 1. 3 (intubation, LMA); also ED95 for incision 1. 6 (no tachy/hyperT to noxious stimuli)
35
How does MAC change with age?
Greatest at 6mo old, then declines | 6% per decade after 40y/o
36
Things that decrease MAC (meds, physiology, pathology, substances)
Meds: Depressants, ketamine, alpha-2 agonists, verapamil, local anesthesia Physio: Increasing age after 1 y/o Path: hypothermia, hypoxia, hypercarbia, anemia, sepsis, hyponatremia Substances: acute EtOH, chronic meth
37
Things that increase MAC (meds, physiology, pathology, substances, genetic)
``` Meds: amphetamines, L-dopa, ephedrine, TCAs Physio: Increasing age < 1 y/o Path: hyperthermia, hypernatremia Substances: chronic EtOH Genetic: red hair ```
38
Things that increase risk of intra-op awareness What are you aware of? When during the surgery? How to manage? (after)
Paralytics, children, chronic drugs/EtOH, surgeries requiring light anesthesia Hearing voices Induction and emergence Counseling
39
Signs of light anesthesia
Tearing, bucking, coughing, dilated pupils, sweating, movement, tachy/hyperT
40
How to prevent intraop awareness?
Premedicate, gas > TIVA, MAC > 0.5-0.7, avoid paralytics, redose IV meds before very stimulating things, increase BP with meds rather than decreasing the gas

Stanford CA-1 Guide (2 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions