anesthetic drugs (inhalants) Flashcards

1
Q

what are the major, minor and not in use yet inhalant anethetics

A

major use

  • isoflurane
  • sevoflurane

minor use

  • desflurane
  • nitrous oxide

not in use yet

  • argon
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2
Q

partition coefficients - B/G and O/G

A
  • isoflurane had higher B/G and O/G = waits longer to get induced and accumulates stronger and longer - need to flush out with O2 to wake naimal up)
  • sevoflurane and desoflurane and N2O have lower B/G and O/G = induced quickly and washed out faster/animal wakes up faster)
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3
Q

understand design of desoflurane vaporizers

A

watch zoom recording

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4
Q

what are the CNS sites of action of inhalant anesthetics

A

spinal cord and brain stem

  • inhibition of: sensory processing, nociceptive signaling, motor response to noxious stimulation

brain

  • hypnosis & amnesia
  • loss of consciousness
  • analgesia
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5
Q

what is MAC

A
  • minimum alveolar concentration
  • the anesthetic concentration preventing motor response to a supramaximal moxious stimulus in 50 % of subjects
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6
Q

MAC dosing

A
  • measure of potency
  • given as vol. - % of Panes (mmHg)
  • agent-specific
  • species-specific
  • correlates inversely with O/G part. coeff.
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7
Q

what are factors that decrease MAC value

A
  • increasing age
  • pregnancy (endogenous opioid release)
  • hypothermia
  • hypotension (MAP < 40 mmHg)
  • CNS depressant drugs/analgesics
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8
Q

what are factors that increase MAC value

A
  • hyperthermia
  • hypernatremia
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9
Q

respiratory system adverse effects

A
  • central respiratory depression
  • decrease Vt: iso> sevo > des
  • bronchodilation
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10
Q

adverse effects on CV system

A
  • decrease MAP
  • decrease systemic vascular resistance
  • decrease myocardial contractility
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11
Q

adverse effects on the liver

A
  • decrease in liver blood flow
  • decreases drug metabolism by 50-70%
  • hepatotoxicity
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12
Q

adverse effects on fetus

A

uteroplacental blood flow is decreased

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13
Q

sevoflurane - formation of compound A

A

lower flow rates make more compound A

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14
Q

what is balanced anethesia

A

concept using a combination of different agents and techniques to produce the four elements of anesthesia

  • hypnosis and amnesia
  • analgesia
  • muscle relazation
  • absence of somatic or autonomuc responses to noxious stimulation
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15
Q

what does lowing inhalant anesthetic dose do

A
  • palpebral reflexes less suppressed
  • hemodynamic parameteres (esp. arterial blood pressures (ABP) often closer to physiological values
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16
Q

where does most of the anesthetic accumuate

A

muscle

17
Q

how can the anesthetist influence onset and depth of anesthesia

A
  • change of partial pressure for the anesthetic (PPanes) or its concentration (Concanes) in inspired gas mixture by: (dialing vaporizer up or down, changing fresh gas flow rate, selecting appropriate circuit system)

because:

  • every change in PPanes or Concanes in the CNS follows changes of PPanes in alveolar gas mixture and arterial blood
18
Q

what are 3 factors affecting inspired gas concentration (Fi) or iPPanes

A
  1. fresh gas flow rate
  2. volume of breathing circuit (apparatus dead space)
  3. absorption
19
Q

factors affecting alveolar concentration

A
  • delivery via circuit
  • pulmonary uptake: blood/gas solubility (B/G) coefficient & pulmonary blood flow (with modern volatile agents almost irrelevant)
  • tissue uptake: tissue solubility of anesthetic agent, tissue blood flow, partial pressure difference between arterial blood and tissues
20
Q

factors affecting arterial concentration

A

depends on ventilation/perfusion (V/Q) mismatching