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SRNAClinical Practicuum Prep > CO2 Waveforms +Pulse oximetry > Flashcards

CO2 Waveforms +Pulse oximetry Flashcards

1
Q

What does the baseline of the CO2 Waveform represents what phase is it?

A

Exhalation of anatomic dead space (flat region before it becomes positive)
Phase I

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2
Q

What does the UPSTROKE of the CO2 Waveform represents ? what phase?

A

Exhalation of anatomic dead space + ALVEOLAR GAS

Phase II

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3
Q

What does the PLATEAU phase of the CO2 waveform represents

A

Exhalation of Alveolar gas

Phase III

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4
Q

What does the return to baseline, DOWNSTROKE phase of the CO2 waveform represents

A

Inspiration of fresh gas that DOES NOT CONTAIN CO2

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5
Q

What is CO2?

A

Carbon dioxide, which is the final product of Aerobic metabolism

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6
Q

Where is End Tidal CO2 measured on the waverform?

A

End of Plateau phase.

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7
Q

What is ventilation

A

Process of removing CO2 from the body.

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8
Q

If you’re using a Mapleson circuit, what is the primary cause of an increase in CO2 ?

A

Inadequate fresh gas flow (no unidirectional valves, no CO2 canisters)

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9
Q

Dead space and CO2

A

increasing dead space, can increase rebreathing and CO2 retention

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10
Q

Valves and CO2 retention

A

A stuck open inspiratory valve rebreathing can occur because during expiration, alveolar gas can back fill the inspiratory limb of the circle
A defective expiratory valve can lead to rebreathing of CO2 also because during inspiration, the negative pressure generated by the patient can bring alveolar gas from the expiratory limb of the circuit.

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11
Q

Malfunction of the _______can also cause CO2 rebreathing

A

CO2 absorber

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12
Q

If the CO2 absorbent malfunction midcase, what do you do?

A

Increase the Fresh gas flow

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13
Q

Classic rebreathing pattern on the capnography will show

A

elevation of the waveform baseline that does not return to and HIGHER ETCO2 , PaCO2 may be normal

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14
Q

What is the Capnometer?

A

Device that measures and displays the concentration of CO2.

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15
Q

What is a Mainstream sampling?

A

INSIDE the tracheal tube with all inhaled and exhaled gas.

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16
Q

Advantage of mainstream sampling vs sidestream sampling

A

ADV: response time is faster
DIS: bulkiness of the device, need to be heated to 40C –> risk of burning patient skin, INCREASE DEAD SPACE

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17
Q

Most common sampling method? What does it require?

A

Sidestream ; Water trap to prevent contamination

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18
Q

What is the average sampling flow rate?

A

150-250 ml/min
If less than 150, too slow
if > 250, may be contaminated with fresh gas

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19
Q

What is use to deal with water condensation?

A

Water trap systems

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20
Q

CO2 measurements done by

A

MASS Spectometry

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21
Q

Mass spectometry work by

A

separating gases and vapors according to difference in their mass-to-charge ratios.

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22
Q

Colorimetric detection consists of a

A

ph sensitive paper within a chamber place between tracheal tube and ventilation device.
Yellow ETCO2>15

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23
Q

CO2 measures 3 vital parameters which are

A

Metabolism
Circulation
Ventilation

24
Q

Normal ETCO2

A

35-45 mmHg

25
Q

The ALPHA angle is between phases

A

II and III

26
Q

What is a normal alpha angle ?

A

between 100-110

27
Q

What conditions are associated with ALPHA angle greater than 110 degrees?

A

Obstructive lung disease
Bronchospasm
Kinked ET tube

28
Q

The BETA angle is between phases

A

III and IV

29
Q

What is a normal Beta angle?

A

Less than 100 degrees

30
Q

What conditions are associated with INCREASED Beta angle?

A

Rebreathing SPECIFIC to FAULTY UNIDIRECTIONAL VALVES

31
Q

What are the characteristics of the CO2 waveform for a patient with COPD?

A

Longer expiratory time
Capnogram with more rounded appearance
Upward slope of the alveolar space.

32
Q

When CO2 absorbent is exhausted what happens

A

Baseline CO2 is increased but BETA ANGLE STAY THE SAME

33
Q

What is the normal PaCO2 to ETCO2 gradient?

A

2-5mmHg.

34
Q

Changes in ETCO2 are usually caused by

A

Changes in CO2 production
Impaired pulmonary perfusion
Impaired ventilation

35
Q

Causes of Increased ETCO2

A

increased production of CO2 delivery of CO2 to the lungs (Increased BMR)
Increased Alveolar ventilation

36
Q

Causes of Decreased ETCO2

A

decreased production of CO2 delivery of CO2 to the lungs (decreased BMR)
Decreased Alveolar ventilation

37
Q

Pulse Oximetry involves the measurement of

A

oxyhemoglobin concentration

38
Q

Pulse Oximetry is based on this law.

A

Lambert-Beer law

39
Q

SPO2 is measured using

A

a pulse to estimate SaO2

40
Q

Pulse oximetry measure 2 wavelengths of light:

A

Oxygenated blood better absorbs near-infrared light (940nm)

DEOXYGENATED blood better absorbs Red light.

41
Q

What does the pulse oximetry look at?

A

the ratio of light during the peak of the waveform relative to the trough of the waveform

42
Q

During the peak of the waveform, what is the relationship of arterial blood to venous?

A

the ratio of arterial blood to venous blood is increased.

43
Q

What does the Lambert-Beer law relates?

A

Intensity of light transmitted through a solution and the concentration of the solute inside the solution (solute:hemoglobin, solution : Blood)

44
Q

What is the formula for SPO2

A

Oxygenated Hgb / Oxygenated Hgb + Deoxygenated Hgb x 100%

45
Q

Better monitoring with probes placed

A

closer to central circulation

46
Q

Associated with FAST SPO2 reading

A

Ear, Nose, tongue, esophagus, Forehead

47
Q

Associated with medium SPO2 reading

A

Finger

48
Q

Slow SPO2 reading on

A

Toes

49
Q

Producing a large and consistent spurious decrease in SPO2?

A

Injection of methylene blue

50
Q

Pulse ox read 80% what is the PaO2 approximately

A

50

51
Q

SPO2 70, 80, 90 Corresponds to PaO2 of ___, ___, and ____respectively

A

40,50,60

52
Q

SPO2 best at monitoring

A

Vascular compression

53
Q

Is the pulse ox a monitor of Anemia

A

No

54
Q

Is the pulse ox a monitor of ventilation why or why not?

A

No

Because patient may be HYPERCABNIC and still have a SPO2 100%

55
Q

is the pulse ox a measure of Bronchial intubation

A

no

56
Q

Blue nail polish

A

May reduce SPO2 reading

57
Q

The most common method of exhaled gas analysis in the OR

A

Infrared absorption

SRNAClinical Practicuum Prep (21 decks)

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