Inhalant Anesthesia Flashcards

1
Q

what is vapor pressure?

A

partial pressure of gaseous phase when in equilibrium with liquid phase

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2
Q

what is the vapor pressure of isoflurane?

A

240mmHg
32%

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3
Q

what is the basic purpose of the anesthesia machine?

A

allow you to control the amount of vapor you deliver to the patient

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4
Q

is there conservation of therapeutic dose (MAC) of inhalant anesthetics across species?

A

yes

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5
Q

what is the definition of MAC?

A

minimum alveolar concentration required to prevent movement in 50% of the patients

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6
Q

what is the MAC of isoflurane in a dog?

A

1.4

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7
Q

what is the MAC of sevoflurane in a dog?

A

2.3

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8
Q

what are some drugs that reduce MAC?

A

acepromazine
alpha 2 agonists
ketamine
opioids- not horses
benzodiazepines
lidocaine

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9
Q

what does it mean that a drug is MAC sparing?

A

drug reduces MAC: lower vaporizer setting needed

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10
Q

how does hypothermia impact MAC?

A

decreases MAC: 5% per degree of celsius

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11
Q

how does age affect MAC?

A

increased age decreases MAC

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12
Q

how does higher cardiac output affect MAC?

A

prevents drug from loading at high enough concentration in blood: slows onset of action

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13
Q

what is the concentration of inhalant in inspired gas with a rebreather determined by?

A

vaporizer setting
how much anesthetic is left in exhaled gas
what percentage of total gas is fresh vs exhaled

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14
Q

which gas is pungent and irritating to mucosa?

A

isoflurane

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15
Q

what are the effects of inhalant anesthetics on the CNS?

A

increase intracranial pressure
CNS depressants

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16
Q

if you spill less than 30ml of inhalant, what should you do?

A

wipe up and discard rag outside

17
Q

are volatile liquid anesthetic drugs flammable?

18
Q

what is sevoflurane vapor pressure?

A

180 mmHg
25%

19
Q

what are the positives of using inhalants instead of injectable anesthetics?

A

predictable, reliable, infinitely adjustable anesthesia
rapid onset and recovery- no metabolism
co-deliver with oxygen so generally good oxygenation
conservation of therapeutic dose across species
easier to create steady state of anesthesia

20
Q

at ________ MAC, cardiovascular depression becomes greater and greater

21
Q

does 1.5xMAC of isoflurane result in the same depth of anesthesia as 1.5xMAC of sevoflurane?

22
Q

what are the MACs for isoflurane and sevoflurane for a cat?

A

isoflurane: 1.6
sevoflurane: 2.6

23
Q

how does minute volume affect uptake of inhalants?

A

higher minute volume brings more inhalant into lungs

24
Q

what is the respiratory minute volume of a dog or cat?

A

180 ml/kg/min

25
is sevoflurane or isoflurane faster onset?
sevoflurane: less soluble also faster recovery
26
what is compound A?
sevoflurane interacts with CO2 absorbent to produce only relevant at fresh gas flow below 15 ml/kg/min
27
which gas may be least impactful on intracranial pressure?
sevoflurane
28
how do inhalants increase intracranial pressure?
impair autoregulation of blood flow hypoventilation contributes to increases in intracranial blood flow
29
how does the respiratory pattern change under inhalants?
changes from slow/deep to rapid/shallow
30
what are the cardiovascular affects of inhalants?
cardiovascular depression- dose dependent myocardial depression decreases cardiac output vasodilation
31
how much of the inhalants are metabolized by the liver?
isoflurane: 0.2% sevoflurane: 5%
32
how do inhalants mainly cause adverse effects on the liver?
causing low cardiac output
33
what are the renal effects of inhalants?
reduce cardiac output which may reduce renal blood flow autoregulation may be affected nephrons may be damaged by reduced cardiac output