Gas Analysis Flashcards

1
Q

Delivery of gases during anesthesia must be ________.

A

tightly controlled

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2
Q

We must know ________we are delivering at all times.

A

how much gas

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3
Q

Several different kinds of ________ are available

A

analyzers

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4
Q

What concept do we use when analyzing gas?

A

diverting or a non-diverting concept

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5
Q

What is a diverting technique?

A

Will use a pump to pull a gas sample into the analyzer where the analysis will take place

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6
Q

What is a non-diverting technique?

A

Will have the meter placed on the in- or expiratory limb of the circuit and the analysis will take place without displacing any gas sample.

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7
Q

What are organic and inorganic anesthetic gas analysis techniques (6)?

A

Infrared absorption, raman scattering, mass spectrometry, piezoelectric analysis, interferometric refractometry and gas-liquid chromatography

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8
Q

What are oxygen analysis techniques (5)?

A

Electrogalvanic cell, polarographic electrode (Clark electrode), paramagnetic oxygen sensor, fluorescence quenching and pH optode

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9
Q

What are carbon dioxide analysis techniques (3)?

A

Infrared absorption analysis, severinghaus PCO2 electrode and fluorescence quenching

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10
Q

What is infrared absorption analysis?

A

Analysis uses each anesthetic gas’s ability to absorb specific frequencies of EMR in the infrared spectrum.

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11
Q

What principle is the foundation of infrared analyzers?

A

Each gas has specific and unique infrared light absorption spectra.

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12
Q

Describe the components (Wavelength and Energy) of red light on the visible spectrum?

A

Longer wavelength and lower energy

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13
Q

What is the relationship between gases and infrared absorption?

A

A sample of a gas or a mixture of gases is subjected to a known range of infrared frequencies.

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14
Q

Infrared absorption Analysis: How can the the specific frequencies of gases be id?

A

The frequencies lost due to absorption are measured, and the gas or gases may be identified by the specific frequencies each gas absorbs.

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15
Q

Anesthetic agents’ infrared absorption spectra are _______ but close in ________.

A

Unique; Frequency

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16
Q

What is important about newer infrared absorption analysis monitors?

A

Capable of identifying specific agents without preprogramming the specific agent.

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17
Q

Infrared absorption Analysis: What determines concentration?

A

The amount of infrared absorption

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18
Q

What does infrared absorption measure?

A

Polyatomic molecules

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19
Q

What can be measured using Infrared absorption Analysis?

A

volatile agents, carbon dioxide, and nitrous oxide

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20
Q

What cannot be measured using Infrared absorption Analysis?

A

OXYGEN AND NITROGEN

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21
Q

What is important to know about HFA propellants (Metered dosed inhalers)?

A

When giving a breathing treatment with an MDI during anesthesia, we inject this HFA into the system and the infrared gas analyzer will be confused and give false readings until no longer in breathing system.

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22
Q

Infrared absorption: What effects the wavelength of the gas?

A

Depends on the specific gas used

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23
Q

What is raman scattering analysis?

A

The interaction of EMR with matter is the underlying principle used with Raman scattering analysis of gases.

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24
Q

What technique is used during raman scattering analysis?

A

Diverting technique to sample the gas

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25
Describe the components of raman scattering analysis.
Raman scattering passes a monochromatic laser beam through a gas mixture, causing an increased vibration frequency of the excited gas molecules. A laser beam interacts with an anesthetic gas molecule, it may be absorbed (as previously described with infrared absorption analysis) or scattered.
26
The scattered frequencies measured in this spectral analysis are represented as _________.
Stokes lines.
27
What is scattering?
A frequency change (energy change) of the initial laser beam after it interacts with gas molecule
28
What is a component of the laser frequency in Raman scattering analysis?
the molecules may be scattered at higher or lower frequencies
29
Each anesthetic gas scatters laser frequencies _______.
uniquely
30
How are gases analyzed in raman scattering?
A gas or gas mixture may be analyzed and identified by comparing the gas sample scattering spectrum to that of known gas scattering spectrum.
31
What does raman scattering technology require?
that a gas molecule be diatomic for identification
32
What can the raman scattering analysis identify?
Oxygen, carbon dioxide, nitrogen, nitrous oxide, and all volatile anesthetics, including mixtures of volatile anesthetics
33
What cannot the raman scattering analysis identify?
Helium (monatomic)
34
What is not required in raman scattering analysis?
Waste gas scavenging, return the sample to the patient circuit
35
What are polyatomic molecules?
Molecules containing more than two atoms {carbon dioxide (CO2) and water (H2O)}
36
Raman scattering analyzers are small and portable but require _________.
calibration
37
What are two situations that make raman scattering analysis less accurate?
high carrier gas flow rates and small tidal volumes as with some pediatric cases
38
What happens if our tidal volumes are not accurate?
we may not be delivering what we think we are (hyperventilating state)`
39
What is mass spectrometry?
ionizes gas molecules and passes them through a magnetic field
40
The gas molecules with the ________ mass-to-charge ratio are easily deflected by the magnetic field and collected by an ion detector.
Lowest
41
Ionized gas molecules with ______ mass-to-charge ratios are deflected less by the magnetic field and detected by other ion detectors.
Higher
42
How is a gas id in mass spectrometry?
amount of deflection
43
What is a historical implication of mass spectrometry?
Mass spectrometry historically has been the dominant technology for anesthetic gas analysis, though it has increasingly been replaced by more portable and efficient infrared absorption analysis and Raman scattering analysis technologies.
44
What two components of are incorporated in piezoelectric gas analysis?
Piezoelectric effect and Henry's Law
45
When will a piezoelectric crystal vibrate?
a set frequency when an electric current is applied to it
46
What is the component of piezoelectric gas analysis?
A vibrating piezoelectric crystal coated with a liquid solution will alter its resonant frequency when exposed to a gas. As the gas dissolves into the liquid, in proportion to its concentration above the liquid gas interphase, the resonant frequency of the crystal is altered.
47
What effects the degree of frequency change in Piezoelectric gas analysis?
proportional to the concentration of gas that dissolves into the liquid
48
"The amount of gas that dissolves into the piezoelectric crystal's liquid coating is directly related to the partial pressure of that gas." What explains this component of piezoelectric gas analysis?
Henry's Law
49
What is a drawback to piezoelectric gas analysis?
does not identify the specific anesthetic agent
50
What is Henry's law?
At a constant temperature, the amount of a given gas that dissolves in a given type and volume of liquid is directly proportional to the partial pressure of that gas in equilibrium with that liquid.
51
What is photoacoustic gas analyzer?
Subjects a gas sample to a filtered, pulsating infrared light beam in a closed chamber
52
What does the pulsating beam cause in photoacoustic gas analyzer?
the gas molecules to increase then decrease in temperature
53
Which law provides the foundation for photoacoustic gas analyzer?
Guy-Lussac's Law, the increase and decrease in temperature causes the chamber pressure to increase and decrease
54
What measures the pressure waves in photoacoustic gas analyzer?
Microphones along the chamber
55
What can photoacoustic gas analyzer measure (3)?
anesthetic gases, mixtures of these gases, and carbon dioxide
56
What is characteristics traits in photoacoustic gas analyzer?
The units are small, portable, and accurate
57
Why can't oxygen be analyzed by infrared absorption?
due to its diatomic structure
58
What are the most common techniques for oxygen analysis (2)?
paramagnetic oxygen analysis and electrochemical oxygen analysis
59
The primary role of oxygen in ___________ underscores the importance of identification and measurement of this gas when delivering anesthetics.
Biological systems
60
What is a common feature of oxygen measurement?
Purposeful redundancy and more than one technology is often used at a time.
61
What do several types of technologies take advantage of for oxygen analysis?
Advantage of oxygen's unique physicochemical properties and interaction with EMR
62
What is an electrogalavanic cell (fuel)?
is also called a fuel cell, because the reaction that takes place creates its own electric current by consuming its “fuel.”
63
What type of analyzer is electrogalvanic cell?
Electrochemical-Oxygen Analyzer
64
What is important about the electrogalvanic sensor?
a membrane that is permeable to gases but not liquids.
65
How does the electrogalvanic cell (Fuel cell) work?
At the anode of the sensor, electrons are liberated in an oxidative reaction. The meter measures the current produced by the electrons consumed in the reaction at the cathode
66
Electrogalvanic cell (Fuel cell): The electron flow between the anode and cathode is ________ to the partial pressure of oxygen in the sample gas.
directly proportional
67
Electrogalvanic cell (Fuel cell): Current flows in ________ to oxygen concentration.
proportion
68
What is important about the life span of electrogalvanic cells?
A limited life related to the concentration and duration of oxygen exposures. - some , some nurse anesthetists remove the oxygen sensor from the circle system if an anesthesia machine is left on
69
What happens if you remove the electrogalvanic cell from the anesthesia machine?
Most anesthesia machines have minimal oxygen flow at all times, so removing the electrogalvanic cell from the flow of higher oxygen concentration will extend its duration of usefulness.
70
What is a drawback to electrogalvanic cell?
Analysis is fairly slow and does not lend itself to accurate measuring of varying expiratory concentrations-it takes time to see this
71
What is the polarographic electrode (Clark Electrode)?
Consists of a voltage source and a current meter connected to a platinum cathode and a silver anode
72
What is polarographic DO sensor?
Is an electrochemical sensor that consists of a silver anode and a noble metal (such as gold, platinum or infrequently, silver) cathode in a potassium chloride (KCl) solution
73
What is the wait time after turning on the Polarographic Electrode (Clark Electrode)?
it requires a 5-60 minute warm-up period to polarize the electrodes before calibrating or measuring.
74
Polarographic Electrode (Clark Electrode): What are the electrodes immersed in?
Potassium chloride electrolyte cell
75
What covers the surface of the Polarographic electrode?
A membrane permeable to oxygen, but not electrolytes
76
What is applied to the electrodes of the Polarographic electrode?
Polarizing voltage (between 0.4 V and 1.2 V is required to reduce oxygen)
77
Polarographic Electrode (Clark Electrode): How are electrons liberated?
At the anode, electrons are liberated by the oxidative reaction of silver with the chloride electrolyte.
78
Polarographic Electrode (Clark Electrode): What does the meter measure?
the current produced by the electrons consumed in the reaction at the cathode
79
Polarographic Electrode (Clark Electrode): How does current flow?
Current flows in proportion to oxygen concentration.
80
Polarographic Electrode (Clark Electrode): What happens if no current is applied to these cells?
no consumption of the electrodes
81
What are the two components of the reaction in Polarographic Electrode (Clark Electrode)?
the oxidation of the silver anode and the reduction of the dissolved oxygen
82
What is diamagnetic?
Most gases, meaning they repel a magnetic field.
83
Is oxygen diamagnetic?
No
84
What is oxygen?
Paramagnetic, meaning it attracts a magnetic field. (This magnetism is weak and only present when oxygen is exposed to a magnetic field)
85
What does the paramagnetic oxygen analysis exploit?
Oxygen's attraction into a magnetic field
86
When exposed to a magnetic field, the oxygen molecules will __________.
align
87
What happens when oxygen molecules align in paramagnetic oxygen analysis?
This will cause a buildup of a pressure wave proportional to the partial pressure of oxygen in the sample.
88
What happens when there is a build up in paramagnetic oxygen analysis?
Will move a small glass dumbbell filled with an inert gas like nitrogen. A small mirror attached to the dumbbell reflects the light and the reflection is measured by a photodiode and the result is displayed digitally.
89
What measures the reflection of light in paramagnetic oxygen analysis?
Photodiode
90
What can paramagnetic oxygen analysis keep up with?
This technique is very fast and can keep up with even very fast respiratory rates.
91
What is the paramagnetic transducer?
Type of oxygen analyzer utilizes the same unique attraction of oxygen molecules to a magnetic field.
92
What does the paramagnetic transducer measure?
the pressure difference between a known gas and a sample gas
93
There are several variations on this principle that measure pressure or flow alterations in relation to the attraction of _______ concentrations to a magnetic field.
Oxygen
94
What does fluorescence generate?
Light
95
What is fluorescence?
When bombarding special molecules with electric current, they will absorb this energy and move some electrons into a higher orbit. This move requires energy, which is provided by the eclectic current bombardment. When these energized electrons return to their normal resting orbit, they emit energy in the form of a photon which is seen as light
96
What determines the color that is emitted during Fluorescence?
The amount of energy these photons release will be reflected in the color, which matches the distance the electron must travel to return to its resting orbit.
97
What are examples of fluorescence (3)?
glow sticks, some sea life, and LED’s (light-emitting diodes)
98
What is fluorescence quenching?
A technology that uses the ability of some gases to absorb these photons and thereby block the light emission.
99
What is the relationship of oxygen to fluorescence quenching?
Oxygen has this ability to quench and if present will absorb a distinct amount of photons and thereby suppressing the emission of light.
100
What effects the amount of florescence quenched by oxygen?
directly proportional to the concentration of oxygen present