| IPG |
circumferential electrodes are
placed on the limb; high-frequency/low voltage current is passed to
measure impedance |
•requires only slight skin
contact |
•false positive
DVT analysis
may result from skin/electrode contacts if scar tissue is present |
75%/90%109
|
| •can
be produced from soft/flexible material |
| •insensitive
to location of measurement |
•low sensitivity |
| •ease of
use |
| SGP |
flexible strain gauge imbibed with mercury is
placed around the limb; changes in the blood volume result in changes
in the impedance of the strain gauge |
•relatively inexpensive |
•sensitive to
temperature variations |
83%/81%110
|
| •does not require
skilled technician |
•requires use of mercury (toxic) |
| PPG |
blood volume is estimated by utilizing
light from LEDs and photodetectors |
•high sensitivity
for arterial disease |
•must fit tightly onto body |
94%/73.1%109
|
| •low-cost
technology |
•LED/photodetector consumes high power |
| •ease of use, widely used |
•low
sensitivity/specificity for venous reflux |
| APG |
chamber
filled with air is placed around the limb;
displacement of air is used to measure changes in blood volume |
•relative ease of use |
•low
sensitivity for venous reflux |
85%/91%109
|
| •more reproducible than SGP |
| •has replaced SGP and PPG in diagnosis of CVI |
