Nitrous Oxide Flashcards Preview

AU '18 - Peds III exam I > Nitrous Oxide > Flashcards

Flashcards in Nitrous Oxide Deck (139)
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1
Q

who synthesized nitrous oxide?

A

Joseph Priestly

2
Q

how did Priestly synthesize nitrous oxide?

A

mixed hot iron filings with nitric acid

3
Q

what did Priestly refer to nitrous oxide as?

A

“phlogisticated nitrous air”

4
Q

who proposed N2O for surgical operations?

A

Sir Humphry Davy

5
Q

who becomes addicted to N2O?

A

Sir Humphry Davy

6
Q

who administered N2O to patients to tx dental pain?

A

Horace Wells

7
Q

who was credited with discovering modern anesthesia?

A

Horace Wells

8
Q

what are the stages of the sedation continuum?

A
  1. minimal sedation
  2. moderate sedation
  3. deep sedation
  4. general anesthesia
9
Q

minimal sedation responsiveness

A

normal response to verbal stimuation

10
Q

minimal sedation airway

A

unaffected

11
Q

minimal sedation spontaneous ventilation

A

unaffected

12
Q

minimal sedation cardiovascular fx

A

unaffected

13
Q

moderate sedation responsiveness

A

“purposeful” response to verbal or tactile stimulus

14
Q

moderate sedation airway

A

no intervention required

15
Q

moderate sedation spontaneous ventilation

A

adequate

16
Q

moderate sedation cardiovascular fx

A

usually maintained

17
Q

deep sedation responsiveness

A

“purposeful” response after repeated or painful stimulus

18
Q

deep sedation airway

A

intervention may be required

19
Q

deep sedation spontaneous ventilation

A

may be adequate

20
Q

deep sedation cardiovascular fx

A

usually maintained

21
Q

general anesthesia responsiveness

A

unarousable even with painful stimulus

22
Q

general anesthesia airway

A

intervention often required

23
Q

general anesthesia spontaneous ventilation

A

frequently inadequate

24
Q

general anesthesia cardiovascular fx

A

may be impaired

25
Q

why do some patients become more sedated than intended?

A
  1. every patient is different

2. responds to sedative drugs in different ways

26
Q

what must you understand before administering N2O?

A
  1. be able to recognize the different levels of sedation

2. be able to rescue from a deeper plane of anesthesia

27
Q

minimal alveolar concentration (MAC)

A

the concentration of a gas required to prevent movement in 50% of people to surgical stimulus

28
Q

MAC of halothane

A

0.75%

29
Q

MAC of isoflurane

A

1.2%

30
Q

MAC of sevoflurane

A

2.0%

31
Q

MAC of desflurane

A

6.0%

32
Q

MAC of N2O

A

104%

33
Q

expected responses from 10-20% MAC

A
  1. body warmth

2. tingling of hands and feet

34
Q

expected responses from 20-30% MAC

A
  1. perioral numbness

2. numbness of thighs

35
Q

expected responses from 20-40% MAC

A
  1. numbness of tongue, hands, feet
  2. droning sounds, distant hearing
  3. sleepiness
  4. euphoria (laughing)
36
Q

expected responses from 30-50% MAC

A
  1. sweating, nausea
  2. increased sleepiness
  3. mild amnesia
37
Q

expected responses from 50-70% MAC

A
  1. dreaming
  2. laughing, giddiness
  3. increased nausea/vomiting
  4. sleepiness increasing toward unconsciousness
38
Q

physical characteristics of N2O

A
  1. colorless
  2. sweet smelling
  3. has high vapor pressure
39
Q

N2O exists as a what?

A

gas

40
Q

N2O is stored as a what?

A

liquid

41
Q

uptake and distribution of N2O

A

quick onset/offset (low blood solubility)

42
Q

N2O blood/gas partition coefficient

A

0.47

43
Q

how long does it take for N2O to take effect?

A

1-3 minutes

44
Q

how long does it take for N2O to have the MAXIMUM effect?

A

<5 min

45
Q

how long does it take to have a complete recovery from N2O?

A

<5 min

46
Q

what can N2O cause if pt is flushed with 100% O2 right after being given N2O?

A

diffusion hypoxia

47
Q

T/F: N2O is easy to titrate

A

true

48
Q

how long does it take to see changes in uptake of N2O?

A

~3-5 min

49
Q

what can affect the uptake of N2O?

A

dependent upon fresh gas flow/size of circuit

50
Q

signs and syms of over-sedation

A
  1. complaints of feeling uncomfortable
  2. nausea
  3. irrational/sluggish responses
  4. perspiration/sweating
  5. non-compliant/combativeness
51
Q

effects of N2O on CNS

A
  1. modest CNS depression
  2. sleepiness/mood alteration
  3. depresses all sensations
  4. inappropriate behavior
52
Q

effects of N2O on CV system

A
  1. HR unchanged
  2. SV, SVR increases slightly
  3. flushing
53
Q

effects of N2O on CV system in anxious pts

A

BP and HR may decrease after N2O

54
Q

effects of N2O on respiratory system

A
  1. negligible effects
  2. MV may slightly increase
  3. not irritating, no mucous
55
Q

what should be clearly described to the pt before administering N2O?

A
  1. how the equipment works (esp mask and tubing)
  2. how minimal/moderate sedation feels
  3. what to do if they feel uncomfortable or nauseous
56
Q

NPO instructions for clear liquids

A

2 hrs

57
Q

NPO instructions for breast milk

A

4 hrs

58
Q

NPO instructions for milk/dairy products

A

6 hrs

59
Q

NPO instructions for light meal

A

6 hrs

60
Q

NPO instructions for fatty meal

A

8 hrs

61
Q

for minimal sedation, what should be avoided for 4 hrs?

A

“heavy meals”

62
Q

for moderate sedation, what should be avoided?

A

ASA guidelines

63
Q

reasons for failure of N2O

A
  1. associated w poor pt selection
  2. weak anesthetic
  3. mild to mod fear (severe anxiety not good pts)
  4. very young children, severe disabilities are poor pts
64
Q

indications for N2O

A
  1. alleviation of mild/mod anxiety
  2. stress reduction in medically compromised
  3. modification of excessive gag reflex
  4. pain threshold elevation
65
Q

contra-indications for N2O

A
  1. pregnancy
  2. deviated septum/nasal obstruction
  3. upper resp tract infection
  4. acute fear/anxiety
  5. inability to communicate
  6. pulmonary hypertension
  7. vitamin B12 deficiency
  8. MTHFR deficiency
  9. CPOD/emphysema
  10. closed spaces (e.g. ear or eye surgery, bowel obstruction)
  11. fire hazard
66
Q

side effects from abusing N2O in vitamin B12 deficient pt

A
  1. hyperpigmentation (ep in distal digits)
  2. hair changes
  3. neuropathy/numbness
  4. unsteadiness
  5. depression
  6. psychosis
  7. Lichtheim’s disease (degeneration of spinal corD)
  8. megaloblastic anemia
  9. increased risk of MI
  10. increased risk of stroke
67
Q

ventilation

A

passage of air from atmosphere to alveoli

68
Q

how does air move?

A

via pressure gradient

69
Q

how is the pressure gradient in ventilation produced?

A

diaphragm

70
Q

T/F: ventilation has a conducting AND respiratory zone

A

true

71
Q

conducting zone

A
  1. oral and nasal pharynx –> 2. trachea –> 3. bronchi and bronchioles –> 4. “dead space”
72
Q

respiratory zone

A
  1. respiratory bronchioles –> 2. alveolar ducts –> 3. alveolar sacs
73
Q

respiratory zone starts at what division?

A

16th

74
Q

obstruction barriers to ventilation

A
  1. physical barrier
  2. laryngospasm
  3. bronchospasm
75
Q

restriction barriers to ventilation

A
  1. lung compliance
  2. habitus
  3. scholiosis
76
Q

paralysis barriers to barriers to ventilation

A
  1. muscle weakness

2. nerve damage

77
Q

oxygenation

A

diffusion of oxygen across

  1. surfactant layer
  2. alveolar epithelium
  3. interstitial space
  4. capillary endothelium
  5. plasma
  6. erythrocyte cell membrane
78
Q

how does diffusion of oxygen work?

A

moves from areas of high partial pressure to areas of low partial pressure

79
Q

what does oxygen bind to?

A

hemoglobin on RBC

80
Q

barriers to oxygenation

A
  1. low O2 partial pressure
  2. small alveolar surface area
  3. increased alveolar thickness
  4. pulmonary edema
  5. anemia
81
Q

T/F: ventilation is oxygenation

A

false, you may be able to ventilate a patient but if you cannot oxygenate them… they will die

82
Q

how can we monitor oxygenation and ventilation?

A
  1. visual and auditory cues
  2. auscultation
  3. pulse oximetry
  4. capnography
83
Q

visual and auditory cues when monitoring pts under N2O

A
  1. chest rise
  2. tidal breathing vs bucking
  3. nasal flaring
  4. retraction of sternal notch
  5. color of mucous membranes
  6. wheezing or “crowing” sounds
84
Q

Do visual and auditory cues monitor oxygenation or ventilation?

A

ventilation

85
Q

which ausculation instrument gives you immediate recognition of apnea?

A

precordial stethoscope

86
Q

Does ausculation monitor oxygenation or ventilation?

A

oxygenation

87
Q

pulse oximetry follows what law?

A

Beer-Lambert law

88
Q

Beer-Lambert law

A

relationship between absorbance and the concentration of an absorbing substance

89
Q

what is the thing absorbed in Beer-Lambert law?

A

light

90
Q

which wavelength is well absorbed by oxyhemoglobin?

A

660 nm - red light

91
Q

which wavelength is well absorbed by deoxyhemoglobin (reduced or “empty” Hgb not bound to O2)?

A

940 nm - infrared light

92
Q

positive cooperativity

A

when a substance (Hgb) binds to substrate (O2), it causes a conformational change in the substance that increases its affinity for the substrate

93
Q

conditions that push rx to TENSED form positive cooperativity

A
  1. increased temp
  2. increased 2,3 BPG
  3. increased CO2
  4. decreased pH (acidosis)
94
Q

conditions that push rx to TENSED form is commonly found where?

A

in the muscles

95
Q

conditions that push rx to RELAXED form positive cooperativity

A
  1. decreased temp
  2. decreased 2,3 BPG
  3. decreased CO2
  4. increased pH (alkylosis)
96
Q

conditions that push rx to RELAXED form is commonly found where?

A

in the lungs

97
Q

O2 saturation drops soon if the oxyhemoglobin dissociation curve is “shifted” to what side?

A

right

98
Q

normal O2 saturation on oxyhemoglobin dissociation curve

A

94-100%

99
Q

O2 saturation on oxyhemoglobin dissociation curve to cause hypoxia

A

<94%

100
Q

O2 saturation on oxyhemoglobin dissociation curve to cause quick desaturation

A

<90%

101
Q

O2 saturation on oxyhemoglobin dissociation curve to cause organ compromise

A

<80%

102
Q

A pt on supplemental O2 can be what for a long time before it registers as a drop in partial pressure of O2

A

apneic

103
Q

pulse oximetry delay in healthy patients

A
  1. 20-30 sec

2. longer w distal appendages

104
Q

pulse oximetry delay in pt that is in shock

A

90 sec or longer

105
Q

measurement errors with pulse oximetry

A
  1. pt movement
  2. decreased pt temperature (cold fingers)
  3. low blood flow (e.g. hypotension, bradycardia)
  4. dark fingernail polish
  5. blood pressure cuff
  6. ambient light
  7. methemoglobinemia
106
Q

does pulse oximetry monitor oxygenation or ventilation?

A

oxygenation

107
Q

measurement of expired CO2 in mmHg on the capnograph

A
  1. waveform

2. numerical value

108
Q

sampling line to nose on capnograph

A
  1. samples expired CO2

2. delivers O2

109
Q

T/F: use of capnography is now required by law in add sedation and general anesthesia cases

A

true

110
Q

phase 0 of capnography monitoring

A

inspiratory downstroke (D-E)

111
Q

at what phase of capnography monitoring is the beginning of inspiration?

A

phase 0

112
Q

what should be approaching baseline unless rebreathing of CO2 occurs of capnography monitoring?

A

phase 0

113
Q

phase 1 of capnography monitoring

A

anatomic deadspace (A-B)

114
Q

T/F: there is exchange in upper airway, nasopharynx in phase 1 of capnography monitoring

A

false

115
Q

at what phase(s) of capnography monitoring are devoid of CO2?

A

phases 0 and 1

116
Q

phase 2 of capnography monitoring

A

expiratory upstroke (B-C)

117
Q

what happens in phase 2 of capnography monitoring?

A
  1. rapid increase in ETCO2

2. emptying of proximal alveoli

118
Q

phase 3 of capnography monitoring

A

alveolar plateau (C-D)

119
Q

what happens in phase 3 of capnography monitoring?

A
  1. slow increase inETCO2

2. emptying of distal alveoli

120
Q

does capnogrpahy monitor oxygenation or ventilation?

A

oxygenation

121
Q

how many standard leads are there in an ECG (EKG)?

A

3

122
Q

lead placement of RA (white) cable for electrocardiogram

A

right arm (“right is white”)

123
Q

lead placement of LA (black) cable for electrocardiogram

A

left arm (“smoke over fire”)

124
Q

EKG leads monitor what?

A

atrial and ventricular depolarization (down and to the left)

125
Q

lead 2 in EKG monitors what?

A

records depolarization at 60 degrees

126
Q

which lead is the most commonly used on monitors?

A

lead 2

127
Q

what manual method should be used to take non-invasive BP?

A

Korotkov method

- inflated cuff placed around limb

128
Q

systolic pressure of Korotkov method

A

appearance of 1st sound

129
Q

diastolic pressure of Korotkov method

A

disappearance of all sound

130
Q

what electronic method should be used to take non-invasive BP?

A

DINAMAP method

131
Q

DINAMAP method

A
  1. device for indirect noninvasive automatic mean arterial pressure
132
Q

normal BP

A

<120 AND <80

133
Q

elevated BP

A

120-129 AND <80

134
Q

high BP (hypertension) stage 1

A

130-139 OR 80-89

135
Q

high BO (hypertension) stage 2

A

≥140 OR ≥90

136
Q

hypertensive crisis

A

> 180 AND/OR >120

137
Q

ADA guidelines of oxygenation monitoring for minimal sedation

A
  1. need to use pulse oximetry

2. oxygen saturation must be evaluated by pulse oximetry continuously

138
Q

ADA guidelines of ventilation monitoring for minimal sedation

A
  1. dentist and/or appropriately trained individual must observe chest excursions
  2. the dentist and/or appropriately trained individual must verify respirations
  3. dentist must observe chest excursions continually
  4. dentist must monitor ventilation and/or breathing by monitoring end-tidal CO2 unless precluded or invalidated by the nature of the pt, procedure or equipment
139
Q

ADA guidelines of BP monitoring for minimal sedation

A
  1. BP and HR should be evaluated pre-operatively, post-operatively and intraoperatively as necessary (unless pt is unable to tolerate such monitoring)
  2. continuous ECG monitoring of pts w significant CV disease should be considered