MAC Values Flashcards

1
Q

What is the blood:gas partition coefficient of halothane?

A

Halothane = 2.54

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2
Q

What is the blood:gas partition coefficient of Isoflurane?

A

Isoflurane = 1.46

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3
Q

What is the blood:gas partition coefficient of N₂O?

A

Nitrous = 0.46

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4
Q

What is the blood:gas partition coefficient of Desflurane?

A

Desflurane = 0.42

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5
Q

What is the blood:gas partition coefficient of Sevoflurane?

A

Sevoflurane = 0.69

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6
Q

Concentration at 1atm that prevents skeletal muscle movement in response to surgical stimulation in 99% of patients.

A

1.3 MAC

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7
Q

What would ED99 be equivalent to in regards to MAC?

A

ED99 = 1.3 MAC

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8
Q

What is MACawake?

A

0.3 - 0.5 MAC: partial awakeness and responsiveness.

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9
Q

What is MACBAR?

A

1.7 - 2.0 MAC: Blunts autonomic responses. No SNS response at all, essentially an overdose.

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10
Q

What is the MAC of N₂O?
What does this mean?

A

N₂O MAC = 104%. Can’t be used as sole anesthetic agent. (MAC can’t be reached without hyperbaric pressures)

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11
Q

What is the MAC of Halothane?

A

0.75%

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12
Q

What is the MAC of Isoflurane?

A

1.17%

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13
Q

What is the MAC of Desflurane?

A

6.6%

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14
Q

What is the MAC of Sevoflurane?

A

1.8%

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15
Q

How much does MAC need decrease as one gets older?
Younger?

A

6% per decade.

↓% for older
↑% for younger

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16
Q

What is the vapor pressure of halothane?

A

243 torr

17
Q

What is the vapor pressure of Isoflurane?

A

238 torr (mmHg)

18
Q

What is the vapor pressure of Desflurane?

A

669 torr

19
Q

What is the vapor pressure of Sevoflurane?

A

157 torr (or mmHg)

20
Q

At what MAC does volatile depression of CMRO₂ begin?

A

0.4 MAC

21
Q

At what MAC would we see EEG burst suppression?
What about total electrical silence?

A
  • 1.5 MAC = burst suppression
  • 2 MAC = EEG silence
22
Q

You have a case where SSEPs and MEPs need to be monitored, what general anesthetics options do you have?

A
  • TIVA
  • N₂O 60% and 0.5 MAC volatile.
23
Q

What specific effects will volatile agents have on SSEPs and MEPs? At what MAC?

A

Dose-dependent (0.5 - 1.5MAC):

  • ↓ amplitude
  • ↑ latency (delayed frequency)
24
Q

At what MAC would you expect to start to see an increase in CBF due to volatile administration?

A

At > 0.6 MAC

25
Q

At what volatile dosage does ICP increase?

A

> 0.8 MAC

26
Q

At what volatile dosage would apnea be seen?

A

1.5 - 2 MAC

27
Q

50% depression of HPV occurs at ___ MAC.

A

2

28
Q

When will sevoflurane begin to cause increases in heart rate?

A

Only at > 1.5 MAC

29
Q

What hepatic blood flow changes are seen with volatile administration? At what MAC might you see these changes?

A

Portal vein dilation = ↑ portal vein flow (at 1-1.5 MAC).
Maintained total hepatic flow.

30
Q

When is N₂O emetogenic?

A

At greater than 50% or 0.5 MAC

31
Q

What is/are the obstetric effects of volatile anesthetics? And at what MAC?

A

Dose-dependent (0.5 - 1.0 MAC) decrease in uterine smooth muscle contractility. (relaxation)

32
Q

What are the major cons of N₂O ? (3)

A
  • Significant N/V @ 0.5 MAC
  • ↑ PVR
  • No surgeries with air filled spaces
33
Q

At what MAC would cerebral autoregulation be lost with halothane?
Sevo?
Iso/Des?

A
  • Halothane lost by 0.5 MAC
  • Sevo lost by 1 MAC
  • Iso/Des lost by 0.5-1.5 MAC
34
Q

At what MAC would you see 100% depression of hypoxic response?
50-70% depression?

A

1.1 MAC ⇒ 100%

0.1 MAC ⇒ 50-70%

35
Q

What are the following properties of Halothane?

  • Blood/Gas Coefficient:
  • MAC:
  • Vapor Pressure:
A
  • Blood/Gas Coefficient: 2.54
  • MAC: 0.75%
  • Vapor Pressure: 243 mmHg/torr
36
Q

What are the following properties of Isoflurane?

  • Blood/Gas Coefficient:
  • MAC:
  • Vapor Pressure:
A
  • Blood/Gas Coefficient: 1.46
  • MAC: 1.17%
  • Vapor Pressure: 238 mmHg/torr
37
Q

What are the following properties of Desflurane?

  • Blood/Gas Coefficient:
  • MAC:
  • Vapor Pressure:
A
  • Blood/Gas Coefficient: 0.42
  • MAC: 6.6%
  • Vapor Pressure: 669 mmHg/torr
38
Q

What are the following properties of Sevoflurane?

  • Blood/Gas Coefficient:
  • MAC:
  • Vapor Pressure:
A
  • Blood/Gas Coefficient: 0.69
  • MAC: 1.8%
  • Vapor Pressure: 157 mmHg/torr
39
Q

What are the following properties of Nitrous Oxide?

  • Blood/Gas Coefficient:
  • MAC:
A
  • Blood/Gas Coefficient: 0.46
  • MAC: 104%