Chapter 8

Question 1

what are the capabilities of plethysmography?

Answer 1

in combo with doppler segmental pressures helps differentiate true claudication from non vascular sources
detect present/ absence of arterial disease while defining its functional aspects
help localize the level of obstruction
-assessment of follow up treatment
-ppg mainly used for evaluation of digits and penile vessels

Question 2

what are some limitations of plethysmography?

Answer 2

cannot be specific to one vessel. tracing reflects all arterial flow beneath the cuff
cant discriminate between major arteries and collateral branches (venous not completely eliminated)
difficult to perform volume plethys on obese patients

Question 3

what is patient position for pleths?

Answer 3

exams should be done in resting position-supine

the patient can be sitting for evaluation of upper limb digits

Question 4

what is an abbreviation for volume (air ) plethys?

Answer 4

PVR

Question 5

what are some principles of volume (air) plethys?

Answer 5

cuffs are placed on specific levels
a measured amount of air is inflated into a cuff to pressure from 10-65 mmHg, depending on cuff size
as arterial flow moved under the cuff, momentary volume changes in limb segment occur
these changes beneath cuff are converted to pulsatile pressure changes within the air-filled cuff bladder
a pressure transducer converts the pressure changes into analog waveforms for display on strip-chart recorder

Question 6

what happens with diastole with cuff bladder?

Answer 6

fixed amount of air pressure in cuff

decrease

Question 7

what happens with systole with cuff bladder?

Answer 7

air pressure in cuff increases as arteries expand

Question 8

what does PPG consists of?

Answer 8

transducer, amplifier, strip chart recorder

Question 9

what does ppg do?

Answer 9

detects cutaneous blood flow, rather than truly measuring volume changes
photocell consists of light emitting diode and photo sensor

Question 10

what does diode transmits with PPG?

Answer 10

infrared light into sub tissue with backscattered light reflected back to the adjacent photo-sensor
the machine is showing us if there is a lot of blood or not

Question 11

what determines the reflection in PPG?

Answer 11

the cutaneous blood

Question 12

what will happen to the reflection if the blood flow is increased?

Answer 12

decrease

Question 13

what will happen to the display when blood flow is increased and decreased reflection?

Answer 13

increase / positive deflection of the waveform

Question 14

what is the techn for volume plethys?

Answer 14

patient supine with heels slightly elevated on cushion
appropriate amount of air used to bring cuff pressure ot predetermined levels. begin with upper part of extremity, moving distally. record at least 3 pulse cycles

Question 15

where is the cuffs applied to for a volume plethys?

Answer 15

thigh, calf, and ankle bilaterally

Question 16

when are brachial pressures obtained?

Answer 16

with doppler segmental pressures

Question 17

why can artifacts form with PVR?

Answer 17

due to improper cuff application

Question 18

T/F similiar gain setting is used throughout the study

Answer 18

true

Question 19

what is a normal waveform for PPG and PVR?

Answer 19

fairly rapid upslope

sharp systolic peak with reflected wave

Question 20

what is a mildly abnormal waveform for PPG and PVR?

Answer 20

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

Question 21

what is a moderately abnormal waveform for PPG and PVR?

Answer 21

flattened systolic peak, upslope and downslope more delayed, reflected wave notch is absent

Question 22

what is severely abnormal waveform for PVR and PPG?

Answer 22

low amplitude or may be absent

Question 23

abnormal waveform always reflect hemodyn signficant disease where?

Answer 23

proximal to level of tracing

severity generally underestimated

Question 24

what can reduced amplitude with no changes to the contour usually mean?

Answer 24

likely reflect insignificant disease unless its unilateral

Question 25

what does abnormal plethys waveform quality suggest?

Answer 25

poor arterial flow with all waveforms are abnormal

Question 26

why would a fair waveform quality accompany abnormal segmental pressures?

Answer 26

b/c collaterals can underestimate significance of obstruction based upon plethys
amplitudes will be similar, but not the waveform qualities

Question 27

how is displacement plethys measured?

Answer 27

by the height of the water in the chimney