Chapter 24: Photo-plethysmography venous

Question 1

PPG of the venous system is used to

Answer 1

document venous insufficiency

venous reflux

Question 2

PPG is used for patients with

Answer 2

chronic swelling
ulcers
varicose veins

Question 3

limitations of venous PPG

Answer 3

cannot do if pt has DVT
skin thickening prevents adequate reading
intact skin required for sensor placement

Question 4

pt positioning for venous PPG

Answer 4

seated with legs dangling

Question 5

PPG can determine

Answer 5

changes in blood content of skin which reflects intravenous volume

Question 6

PPG consists of

Answer 6

photocell which consist of light emitting diode and photo sensor

Question 7

PPG diode

Answer 7

transmits infrared light into subcutaneous tissues

this light is reflected back to photo sensor

Question 8

what determines the reflection

Answer 8

cutaneous blood flow

Question 9

increased blood flow results in

Answer 9

increased attenuation which decreases reflection

displayed as a positive upstroke

Question 10

electrical coupling is a

Answer 10

method to increase gain and display signal

Question 11

two types of electrical coupling

Answer 11

DC and AC

Question 12

DC coupling

Answer 12

direct current
voltage either positive of negative
current flows in only one direction

Question 13

DC coupling detects

Answer 13

slower changes in blood content

Question 14

DC coupling is used for

Answer 14

venous studies

Question 15

AC coupling

Answer 15

alternating current
voltage reverses polarity 60 times a second
current flows in both directions

Question 16

AC coupling detects

Answer 16

fast changes in blood flow

Question 17

AC coupling is used for

Answer 17

arterial studies

Question 18

calibration of PPG for venous studies

Answer 18

not calibrated volumetrically
maintain same size or gain throughout study
difference in tracing should mean difference in blood volume

Question 19

PPG display

Answer 19

arterial pulsations evident and super imposed on tracing of venous flow

Question 20

PPG test set up

Answer 20

sensor applied to LE 5-10cm above medial malleolus
must not be over varicosity
patient completes a series of exaggerated dorsiflexions to empty calf veins
manual compression of calf can be performed (bilaterally to ensure consistency)

Question 21

the strip chart recorder for venous PPG

Answer 21

running slow 5mm/sec

stylus records heat on paper

Question 22

after dorsiflexion of food or manual compression

Answer 22

tracing continues to be obtained

record venous refill time/venous reactive time (VRT)

Question 23

if the VRT is <20 seconds

Answer 23

study must be repeated with tourniquet applied to eliminate influence of superficial system

Question 24

Normal venous refill time

Answer 24

> or = to 20 seconds without tourniquet

Question 25

abnormal refill time/ superficial system incompetence

Answer 25

VRT <20 seconds without tourniquet but normalizes

VRT >20 seconds with tourniquet

Question 26

Deep system incompetence refill time

Answer 26

<20 seconds with and without tourniquet application

Question 27

absent deflections or grossly irregular tracings

Answer 27

check if its on DC mode

Question 28

deflections of the scale or barely discernible

Answer 28

adjust gain
sensitivity
size setting