Chapter 8: Plethysmography (UE and LE)

Question 1

purpose of plethysmography

Answer 1

in combination with doppler segmental pressures it helps differentiate true claudication from non vascular sources

Question 2

plethysmography can

Answer 2

detect presence or absence of arterial disease while defining its functional aspects

Question 3

plethysmography helps to

Answer 3

localize the level of obstruction

assess follow-up treamenet

Question 4

PPG is mainly used for

Answer 4

eval of digits and penile vessels

Question 5

limitations of plethysmography

Answer 5

not specific to one vessels
tracing reflects all arterial flow beneath cuff
cannot tell major arteries vs collateral branches
limited due to body habitus

Question 6

plethysmography patient positioning

Answer 6

patient supine limbs in resting position

pt can also be sitting for eval of upper limb digits

Question 7

Volume air plethysmography

Answer 7

measurement of volume change

Question 8

volume air plethysmography technique

Answer 8

pneumatic cuffs placed around specific levels of extremities or digits
a measured amount of air is inflated into cuff ranging from 10 to 65mmHg depending on cuff size

Question 9

volume air plethysmography how does it work

Answer 9

as arterial flow moves under the cuff, volume changes in the limb segment occur
these changes re converted to pulsatile pressure changes within the air-filled cuff

Question 10

how are results gathered with volume air plethysmography

Answer 10

a pressure transducer converts the pressure changes into analog waveforms and display on strip-chart recorder

Question 11

chart paper speed

Answer 11

25mm/sec

Question 12

during diastole

Answer 12

fixed amount of air pressure in cuff

Question 13

during systole

Answer 13

air pressure in cuff increases as arteries expand

Question 14

Photo-phlethysmography (PPG) consists of

Answer 14

transducer, amplifier, strip chart recorder (paper speed 25 mm/sec)

Question 15

PPG detects

Answer 15

cutaneous blood flow rather than truly measuring volume change

Question 16

photocell in PPG consists of

Answer 16

light emitting diode and photo sensor

Question 17

PPG diode

Answer 17

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

Question 18

the cutaneous flow in PPG deteremines

Answer 18

the amount of reflection

Question 19

the PPG the blood attentuates

Answer 19

light in proportion to its content in tissue

Question 20

increased blood flow results in

Answer 20

increased attenuation
decreases reflection
this is displayed as positive upstroke waveform

Question 21

volume plethysmography technique

Answer 21

pt supine
heels slightly elevated on cushion
use 3 or 4 cuff method penumatic cuffs applied snugly to thigh calf and ankle bilaterally
machine performs self calibration when activated
bilat brach pressures obtained during segmental pressure exam
start at upper extremity and move distally
record at least 3 pulse cycles

Question 22

volume plethysmography air pressures are

Answer 22

predetermined

Question 23

volume plethysmography artifacts

Answer 23

not uncommon due to improper cuff application

Question 24

gain should be kept

Answer 24

similar throughout the study

if different setting is used note it on recording paper

Question 25

both PPF and volume plethysmography are evaluated usuing

Answer 25

qualitative criteria described by DE strandness and J Raines

Question 26

PPG results: normal

Answer 26

fairly rapid upslope, sharp systolic peak with reflective wave

Question 27

PPG results: mildly abnormal

Answer 27

sharp peak
absent reflected wave
downslope is bowed away from baseline

Question 28

PPG results: moderately abnormal

Answer 28

flattened systolic peak
upslope and downslope more delayed
reflected wave (notch) absent

Question 29

PPG results: severely abnormal

Answer 29

low amplitude or may be absent

Question 30

abnormal waveforms during PPG reflect

Answer 30

hemodynamically significant disease proximal to level of tracing

Question 31

reduced amplitude with no changes i the contour of wave is likely to reflect

Answer 31

insignificant disease unless its unilateral

Question 32

a fair waveform with abnormal segmental pressures means

Answer 32

collaterals which underestimate significance of obstruction

Question 33

if you can’t center the stylus

Answer 33

check the mode
AC mode for arterial
DC mode for venous

Question 34

stylus wandering on paper

Answer 34

activate the re-set control and be sure correct exam function is selected

Question 35

unable to obtain clean waveform

Answer 35

reapply PPG

pt must remain still, tremors make it impossible

Question 36

if you’re not getting a tracing

Answer 36

check exam mode, paper, and connection points

Question 37

Displacement plethymography

Answer 37

any change in volume of the enclosed part will displace an equal amount of water

Question 38

Displacement plethymography : displacement is measured by

Answer 38

the height of the water in the chimney

Question 39

Displacement plethymography :volume change is measured by

Answer 39

spirometer

Question 40

Pulse plethysmography refers to

Answer 40

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