Uptake and distribution Flashcards

1
Q

Uptake =

A

ƛ * Q * (A-v) Solubility * CO * difference in alveolar/venous partial pressures

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2
Q

Solubility’s effect on the rate of rise of FA/FI curve:

A

Less soluble = faster rate of rise

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3
Q

Over pressurization

A

The use of high FD to increase the speed of FA=FI equilibration

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4
Q

Effect of CO on induction speed:

A

Increasing Cardiac Output = decreased speed of induction

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5
Q

Tissue uptake equation:

A

Uptake = tissue/blood coefficient * flow * (a-t)

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6
Q

The coefficient that most influences FA/FI rise:

A

Blood/Gas

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7
Q

The coefficient that most influences the FA/FI tail:

A

Tissue-gas

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8
Q

MAC

A

Minimum alveolar concentration; ED50 of inhaled anesthetics. The concentration that will produce absence of movement in 50% of the population.

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9
Q

↑ ventilation will have more of an effect on FA/FI curve for this type of agent:

A

Highly soluble agent

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10
Q

Effect of both ↑ ventilation and ↑ CO:

A

↑ ventilation has more effect (to speed induction) than ↑ CO does (to slow it)

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11
Q

If only one lung is intubated, what is the effect on the rise in FA and rise in Pa?

A

FA rises faster than if the ETT was in the trachea However, loss of uptake from unventilated lung leads to overall depressed ↑ in Pa

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12
Q

Higher blood-gas coefficient means:

A

Agent is more soluble More agent in blood = less in alveoli/brain

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13
Q

Type of gas that will washout fastest:

A

Least soluble

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14
Q

N2O is ____x as soluble as nitrogen:

A

34x

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15
Q

Places that N2O can diffuse into during surgery:

A
  1. ETT cuff 2. Bowel obstruction 3. Pneumothorax/pneumocephalus 4. Inner ear 5. Ophtho procedures using gas bubbles 6. Air embolus
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16
Q

Another name for blood-gas partition coefficient:

A

Oswaldt Solubility Coefficient

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17
Q

Brain-level activity of a highly vs. minimally soluble IA:

A

Highly soluble: low brain activity Minimally soluble: high brain activity

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18
Q

Effect of solubility on emergence

A

Less soluble = faster induction/emergence More soluble = slower induction/emergence

19
Q

Five partial pressure gradients between vaporizer and end-target tissue:

A

Vaporizer and inflow, Inflow and circuit, Circuit and alveoli, Alveoli and blood, Blood and tissues

20
Q

Impact of HCT on B/G coefficient:

A

↓ HCT = ↓ B/G coefficient Dropping HCT from 21 –> 43 drops B/G coefficient by 20% D/t less binding sites in the blood

21
Q

FA vs. FI:

A

FA = alveolar concentration FI = inspired concentration

22
Q

FD = FI when:

A

High flow rate with no re-breathing

23
Q

Make these changes to ventilation to ↑ uptake:

A

↓ TV, ↑ rate

24
Q

PA of volatile anesthetic is determined by (4):

A
  1. PI (inhaled partial pressure) 2. Alveolar ventilation 3. Breathing circuit 4. FRC
25
Q

Normal alveolar ventilation, minute ventilation and deadspace:

A

Alveolar Ventilation = 4 L/min Minute ventilation = 6 L/min Dead space = 2L/min

26
Q

Solubility’s effect on the rate at which FA approaches FI:

A

Less soluble agents will reach equilibrium faster They have a faster rate of rise

27
Q

Describe the FA/FI curve:

A

First rise: VRG uptake First knee: VRG at equilibrium Second rise: MG uptake Second knee: MG at equilibrium Third rise: FG/VPG uptake (very slow)

28
Q

With lower solubility (

A
  1. Gas phase 2. Blood phase
29
Q

What determines which direction the gas will move

A

pressure gradients

30
Q

How long does it take the fat compartment to reach equilibrium?

A

24-48 hours

31
Q

Rate of induction/emergence of an anemic patient

A

Faster induction and emergence

32
Q

What determines how quickly FA= FI ?

A

Solubility - less soluble = faster equilibrium

33
Q

Partial Pressure that represents anesthetic going to the brain

A

FA (fraction of alveolar concentration)

34
Q

What do we as anesthetists control

A

FI (fraction of inspired concentration) - the % dials

35
Q

What is out overall goal with induction

A

Get the FA/FI ratio to 1:1 quickly - the faster to equilibrium - the faster the induction

36
Q

PA (alveolar pressure ) is used to estimate 3 things

A
  1. Depth of anesthesia 2. Recovery from anesthesia 3. Anesthetic Potency (dose) or MAC (ED50)
37
Q

Exhaled gas readings during induction and emergence. During induction readings will be ____________ than what is set on the dial d/t ________________. During emergence the readings will be higher than what is set on the dial d/t ___________.

A

Induction - lower; Uptake occurring in the tissues Emergence - higher; tissue giving up previously absorbed IA

38
Q

What has a faster induction, iso or des?

A

des- it is less soluble and has a faster rate of rise and therefore reaches equilibrium much faster.

39
Q

Why does nitrous have a faster rate of rise than desflurane?

A

Despite des being less soluble nitrous will rise faster because of the concentration effect.

40
Q

What opposes the effect of ventilation?

A

Uptake

41
Q

A increase in CO will cause a ____________ in the FA/FI ratio. this means that the patient will be induced ___________.

A

Decrease Slower

42
Q

A decrease in CO will cause a ____________ in the FA/FI ratio. this means that the patient will be induced ___________.

A

Increase Faster

43
Q

Changes in CO will have a greater effect on the ____________ soluble agents. Why?

A

More soluble. They have more time to equilibrate with the passing blood.

44
Q

Changes in ventilation will have greater effects on ______________ agents. Why?

A

More Soluble. Alveolar pressure will build up much faster in both, but the rate of rise will increase more for the highly soluble agents.