Plethysmography UE and LE

Question 1

Limitations of plethysmography?

Answer 1

a) cannot be specific to one vessel. Tracing reflects all arterial flow beneath the cuff.
b) cannot discriminate between major arteries and collateral branches
c) difficult to preform on obese patients

Question 2

What does PVR stand for?

Answer 2

pulse volume recording

Question 3

What is the process of volume plethysmography?

Answer 3

a) measured amount of air is sequentially inflated into a cuff to pressure ranging from 10 to 65 mmHg depending on cuff size
b) as arterial flow moves under the cuff, momentary volume changes in the limb segment occur.
c) these changes beneath cuff are converted to pulsatile pressure changes within the air filled cuff bladder
d) A pressure transducer converts the pressure changes into analog waveforms for display on strip-chart recorder

Question 4

What occurs during diastole and systole?

Answer 4

diastole: fixed amount of air pressure in cuff
systole: air pressure in cuff increases as arteries expand

Question 5

What does PPG stand for?

Answer 5

photo-plethysmography

Question 6

What does PPG detect?

Answer 6

cutaneous blood flow rather than truly measuring volume change.

Question 7

What do the PPG photocells consist of?

Answer 7

light emitting diode and photo-sensor

Question 8

How does the PPG work?

Answer 8

the diode transmits infrared light into subcutaneous tissue with backscattered light reflected back to the adjacent photo-sensor

Question 9

Blood attenuates light in proportion to its content in tissue. _____ blood flow results in _______ reflection.

Answer 9

increased, decreased

Question 10

Normal and mildly abnormal PPG waveforms?

Answer 10

normal: fairly rapid upslope, sharp systolic peak with reflective wave
mildly abnormal: sharp peak, absent reflected wave, downslope is bowed away from baseline

Question 11

moderately abnormal and severely abnormal PPG waveforms?

Answer 11

moderately: flattened systolic peak, upslope and downslope more delayed, reflected wave (notch) absent
severely: low amplitude or may be absent

Question 12

Abnormal waveforms always reflect hemodynamically significant disease proximal or distal to level of tracing?

Answer 12

proximal

Question 13

A fair waveform quality may accompany abnormal segmental pressures because _____ can underestimate significance of obstruction based upon plethysmography.

Answer 13

collaterals

Question 14

How is displacement plethysmography demonstrated?

Answer 14

Any change in volume of the enclosed part will displace an equal amount of water. Displacement is measured by the height of water in the chimney.

Question 15

Pulse plethysmongraphy refers to transient changes in limb volume related to the pulse by pulse activity of the left ventricle. The body part expands when _____ inflow exceeds ________ outflow.

Answer 15

arterial, venous

Question 16

What is is the pulse recorded speed for toes?

Answer 16

5mm/sec

Question 17

The increase in toe volume is secondary to obstruction of venous out flow. Plethysmography measures what volume changes?

Answer 17

All volume changes

Question 18

Technique for fingers with cold stress?

Answer 18

a) after resting study is preformed, hands are immersed in ice cold water for 3 minutes if possible
b) following cold stress, waveforms and pressures are obtained immediately and five minutes later
c) document patient symptoms, skin color observations and other pertinent findings on the report form

Question 19

Waveform amplitudes are usually greater in toes or fingers?

Answer 19

fingers

Question 20

What is the difference between normal and abnormal waveforms in digits?

Answer 20

Normal has a prolonged down stroke with a notch halfway down. Abnormal has a sharp anacrotic notch present higher on the downslope

Question 21

What describes the peaked pulse characteristically seen in the digit pulse contours of patients with raynauds phenomena?

Answer 21

sumner and strandness

Question 22

Following cold immersion, abnormal cold sensitivity is likely if the amplitude fails to return to baseline levels within how many minutes?

Answer 22

5

Question 23

digit pressure measurements
finger/brachial indices:
toe/brachial index:

Answer 23

0.8-0.9

normal toe P’s vary 60-80% of brachial P’s

Question 24

Capabilities of transcutaneous oximetry TcPO2?

Answer 24

Wound healing and amputation level determination.

Reflects tissue oxygen tension and relies on a balance between oxygen supply and consumption.

Question 25

What are the principles of transcutaneous oximetry TcPo2?

Answer 25

Electrode heats skin to 45 degrees C
Blood flow increase, lipid layer in fatty tissue melts, more oxygen escapes through skin and measured by sensor in electrode.

Question 26

After manual calibration of transcutaneous oximetry, it take approximately how long to obtain pO2 reading?

Answer 26

15-20 minutes/site

Question 27

Interpretations of transcutaneous oximetry?

Answer 27

Normal: healing should occur with pO2 reading of 70-80 mmHg
borderline healing: 30-40 mmHg
non-healing: 10-15 mmHg