Plethysmography (UE, LE) Flashcards

1
Q

What does Plethysmography do?

A

Checks changes in volume PVR

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2
Q

What are the capabilities of plethysmography?

A

-In combination with Doppler segmental pressures helps differentiate true claudication from non-vascular sources.
- Detect presence/absence of arterial disease while defining tis functional aspects
- Helps localize the level of obstruction

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3
Q

What is PPG mainly used for?

A

Evaluation of digits and penile vessels

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4
Q

What are the limitations of Plethysmography (UE, LE)?

A
  • Cannot be specific to one vessel
  • Cannot discriminate between major arteries and collateral branches
  • Difficult to perform on obese patients
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5
Q

How should the patient be positioned?

A
  • Most exams can be done with the limbs in a resting position (supine)

*Patient can be sitting for evaluation of upper limb digits

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6
Q

What are the physical principles of plethysmography?

A

Volume (air) Plethysmography

** measurement of volume changes

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7
Q

A measured amount of air is sequentially inflated into a cuf to pressure ranging from _____________.

A

10 - 65, depending on cuff size

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8
Q

A pressure transducer converts the pressure changes into _____.

A

Analog waveforms that display on strip-charts

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9
Q

Chart paper speed = __________

A

25 mm/sec

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10
Q

What the amount of cuff pressure in diastole and systole?

A

Diastole: fixed
Systole: increases as arteries expand

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11
Q

What does a photo-plethysmography consist of?

A

Transducer, Amplifier, Strip-chart recorder

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12
Q

What does photo-plethysmography detect?

A

Cutaneous blood flow

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13
Q

What does photocell consist of?

A

light emitting diode and photo-sensor

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14
Q

What transmits infrared light into subcutaneous tissue with backscattered light reflected back to the adjacent photo sensor?

A

Diode

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15
Q

What determines the amount of reflection with photo-plethysmography?

A

cutaneous blood flow

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16
Q

Blood attenuates light in what?

A

proportion to its content in tissue

17
Q

Increased blood flow results in:

A

increased attenuation

18
Q

Increased blood flow results in increased attenuation which decreases what?

A

reflection

19
Q

How is increased blood flow displayed?

A

positive upstroke of the waveform

20
Q

How is decreased reflection displayed?

A

positive upstroke of the waveform

21
Q

What is the positioning for Volume Plethysmography?

A

Supine, with heels slightly elevated on cushion

22
Q

What method is used for Volume Plethysmography?

A

3 to 4 cuff method

23
Q

What does the machine do when activated?

A

Perform a self-calibration

24
Q

What bilateral pressures are obtained?

A

Brachial

25
Q

Begin with the upper part of extremity, moving distally. Record at lest _________ cycles.

A

3

26
Q

Artifact is common due to what?

A

Improper cuff placement

27
Q

Volume plethysmography and _______ are complementary.

A

Pressures

28
Q

Both “volume” and “photo” plethysmography are evaluated using:

A

qualitative criteria

29
Q

Normal interpretation of Photo-plethysmography PPG?

A

fairly rapid upslope, sharp systolic peak with reflected wave

30
Q

Mildly abnormal interpretation of Photo-plethysmography PPG?

A

Sharp peak, absent reflected wave, downslope is bowed away from baseline

31
Q

Moderately abnormal interpretation of Photo-plethysmography PPG?

A

Flattened systolic peak, upslope and downslope more delayed; reflective wave (notch) absent

32
Q

Severely abnormal interpretation of Photo-plethysmography PPG?

A

Low amplitude, or may be absent

33
Q

Abnormal waveforms always reflect:

A

hemodynamically significant disease proximal to level of tracing

34
Q

Reduced amplitude with no changes in the contour is likely to reflect what?

A

insignificant disease, unless it is unilateral

35
Q

Why might a fair waveform quality be accompanied by abnormal segmental pressures?

A

because collaterals can underestimate significant of obstruction based upon plethysmography

36
Q

How is displacement measured with displaced plethysmography?

A

by the height of the water in the chimney

37
Q

How is volume measured with displaced plethysmography?

A

spirometer

38
Q

What does pule plethysmography refer to?

A

transient changes in (limb) volume related to the “pulse by pules” activity of the left ventricle; the body part expands when arterial inflow exceeds venous outflow