Nagelhout videos- Volatiles Flashcards

1
Q

4 components of general anesthesia

A
  1. Amnesia - loss of memory
  2. anesthesia- loss of consciousness
  3. Analgesia - freedom from pain (Inhalationals are poor analgesics- think- that’s why a lot give fentanyl during timeout- to blunt the sympathetic response to pain)
  4. Muscle relaxation
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2
Q

How many stages of anesthesia

A

4

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3
Q

Stage of anesthesia from when pt is first exposed to anesthetic agent to the time they lose consciousness

A

Stage 1

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4
Q

What does anesthesia produce

A

loss of consciousness

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5
Q

Stage 2- pupils dilated or constricted

A

dilated - body is thinking wtf is going on

+nystagmus due to cerebral cortex suppression

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6
Q

Why does the excitatory phase of anesthesia happen?

A

Because the inhibitory pathways are affected first and you go to sleep, then you have the excitatory pathways which are harder to anesthetize.

so during the excitatory phase you can kind of say you have unopposed stimulatory neuronal pathways acting up before they become anesthetized

*Patient not deep enough yet

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7
Q

Stage of surgical anesthesia

A

Stage 3

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8
Q

Stage 3 of anesthesia begins with what?

A

The onset of regular, rhythmic respirations

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9
Q

What’s the first airway reflex to get knocked out?

A

Swallowing > wretching/gagging > vomiting

  • also the last to come back, which is why it’s important to look for swallowing as your emerging the patient
  • if they can swallow, they can protect their airway (gag/cough reflex has returned)
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10
Q

Explain MAC - minimal alveolar concentration

A

*the dose of an anesthetic

How much gas do I need to have in your lungs so you don’t move when the surgeon cuts (in 50% of population)

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11
Q

The absolute minimum of Fio2 you can give of o2 with anesthesia

A

30%

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12
Q

Why can you only give 70% nitrous?

A

Because you at minimum need to have 30% oxygen in the lungs

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13
Q

Blood gas solubility of nitrogen

A

0.014

(nitrous = 0.47) (~ 34x more soluble) - occupies a larger volume of space

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14
Q

What age is MAC the highest in?

A

6 months old

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15
Q

How much does MAC decrease with age?

A

6% every decade after 40yo

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16
Q

Why do kids go to sleep faster than adults despite faster metabolism and faster cardiac output?

A

They breathe faster. Faster you breathe in the anesthetic, faster you go to sleep.

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17
Q

How is MAC affected by pregnancy?

A

No change

-increased CO (slower induction) + increased RR (faster induction) = cancels eachother out

I’m gonna say no and that MAC is decreased due to increased progesterone - decreases 30-40%

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18
Q

Do fat people go to sleep faster or slower?

A

Neither. Same time as the non-obese person.

-Yes they have more fat but fat gets very little blood flow (anesthetic goes to VRG and then muscle before going to fat)

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19
Q

Do fat people wake up faster or slower?

A

Slower - especially if it’s a long case (2-3hrs) - “Reservoir effect” - inhalational agents are so lipid soluble that it will remain in the fat . More fat = more absorbed inhalational to get rid of

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20
Q

What are the volatile anesthetics and why are they called that?

What about non-volatile anesthetics?

A

Iso, Sevo, Des

because they come as a liquid and need to be vaporized into gaseous form . You need to “volatilize” aka “vaporize” them

Nitrous is the only non-volatile inhalational agent (supplied in gaseous form)

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21
Q

What is the only inorganic molecule? And what does that mean?

What are all the others?

A

Nitrous oxide - means it doesn’t have a carbon molecule attached to it

All others = halogenated ethers (contain a carbon molecule ROR/C-O-C bridge, ether bridge)

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22
Q

What are the 4 “halogenated” molecules on the periodic table?

A

Fluoride
Chloride
Bromine
Iodine

(Strongest negatively charged elements on the periodic table)

23
Q

R-O-R =

A

ether molecule

24
Q

__________ is a halogenated hydrocarbon

A

Halothane

25
Q

3 Primary sites in the brain where anesthetics produce anesthesia (unconsciousness)

A
  1. Brainstem
  2. Thalamus
  3. Cortex
26
Q

2 Primary sites in the brai nwhere anesthetics produce amnesia

A
  1. Hippocampus

2. Amygdala

27
Q

Primary site where anesthetics produce analgesia

A

Spinothalamic tract (sensory) (little analgesic properties)

28
Q

Primary site where anesthetics produce immobility

A

Spinal cord

29
Q

Someone asks you what does anesthesia do to the pancreas?

A

It depresses it. (Good answer for anything- it depresses everything [in a dose dependent fashion])

30
Q

What do inhalationals do to CMRO2?

A

decrease it (cerebral metabolic rate of o2 consumption - brain slows down- it doesn’t need to consume as much o2)

31
Q

What 2 drugs can raise intraoccular pressure?

A

Ketamine & Sux

ketamine sux for eyeballs

32
Q

What do inhalational anesthetics do to ICP?

A

increase ICP secondary to cerebral vasodilation (increased CBF = increased cerebral blood volume = increased ICP)

33
Q

CCP =

A

MAP - ICP

34
Q

How can you decrease ICP? (5)

A
  1. elevate hob to promote venous drainage
  2. minimize peep (increased intrathoracic pressure can impede venous drainage from the head)
  3. decrease the water in the brain (mannitol)
  4. decrease the blood volume in the brain (hyperventilate –> CO2 drops –> vasoconstriction)
    * if you hyperventilate too much, you pass out secondary to decrease in cerebral blood flow
  5. Remove CSF with a drain
35
Q

What is considered the blood pressure of the brain?

A

CPP

MAP-ICP
50-150
Autoregs at a map of 60-180

36
Q

At what maps can the brain autoregulate to maintain it’s own perfusion pressure?

A

60-160 (or 180)

37
Q

T/F: Nitrous has analgesic properties

A

True ! yay

38
Q

The 5 mechanisms by which volatile anesthetics produce hypotension

A
  1. CNS depression - depresses vasomotor centers- reduced sympathetic outflow
  2. Direct cardiac depression
  3. Vascular smooth muscle relaxation
  4. Decreased baroreceptor response
  5. Depress the release of BP supportive hormones (Renin, catecholamines, vasopressin, etc)
39
Q

How do volatiles affect respiratory rate compared to opioids?

A

Volatiles decrease TV

Opioids decrease RR

40
Q

How does nitrous affect respirations?

A

It doesn’t

41
Q

True/False: it is safe to use nitrous oxide in someone with MH

A

True

42
Q

What do you know about homocysteine

A
  1. It’s converted to methione by methionsynthase by vitamin B12
  2. It’s synthesis results in products of DNA and RNA
  3. With prolonged exposure, Nitrous oxide non-competitively binds (permanently) and inactivates vitamin B12 (6hrs)
  4. Homocysteine cannot be synthesized to make DNA/RNA products
43
Q

Which gas is loosely associated with “Immune deficiency”

A

Nitrous

  • bc of vitamin b12 inactivation
  • cant make DNA/RNA products that result from Homocysteine > Methionine
44
Q

What is the enzyme that’s inhibited by nitrous oxide that blocks the synthesis of DNA and RNA

A

Methioninesynthase

meth-i-an-een synth-a-sase

45
Q

What is the cofactor that is inhibited by nitrous oxide

A

vitamin B12

46
Q

T/F- all inhalational agents relax the uterus

A

True- don’t want to do this in a pregnant woman

> decreased uterine tone
BLEEDING (this is part of the reason why spinals are #1)
the uterus needs to contract/cramp to stop bleeding
can lead to spontaneous labor

47
Q

50% nitrous oxide is equivalent to how many mg of IV Morphine?

A

15mg

48
Q

For every 10% of nitrous you turn on, you can give ____% less gas.

A

10%

-so 50% nitrous, cuts your gas in half

49
Q

Rapidity of recovery is (directly/inversely) proportional to the solubility of the anesthetic.

A

inversely

  • increased solubility
  • slower wakeup
50
Q

On average, red heads require ___% more desflurane to prevent movement

A

20%

51
Q

What are the 2 major determines of speed of an anesthetic?

A

-inspired concentration (how high you turn the vial on)

& blood solubility

52
Q

Boiling point of Sevo, Iso, Des.

Significance?

A

Nitrous- -88C
Des- 25
Iso 50
Sevo 60

-Des will boil at room temp

53
Q

Define vapor pressure

A

The atmospheric pressure at which a gas will vaporize into a liquid

54
Q

Vapor pressures of Sevo, Iso, Des

which is the easiest to vaporize and why?

A

Sevo- 160
Iso- 240
Des- 669
Nitrous- 34,770

Des will be the easiest to vaporize because its closest to 760 (ATM pressure where the liquid becomes a gas)