Chapter 26 Flashcards
what is the capabilities of air plethysmography?
to evaluate venous function e.g document venous insufficiency/ quantitate venous reflux
what are limitations for APG?
inability of patient to maintain position or perform exercise
cast, traction, or heavy non removable bandages
will not diagnose incompentent perforators or isolated incompetent distal veins
what is patient positioning for APG?
supine then assumes variety of standing positions
what are physical prinicples of APG?
pleths measure volume changes
pnematic cuff connected to pressure transducer, volume changes amplified and convered to analog display
documents volume changes secondary to position changes/ exercise
what is the technique for APG?
patient supine, cuff applied to lower leg, air injected into cuff to a specific pressure level, manual calibration competed
leg passively elevated to empty venous system (zero venous volume)
patient quickly stand bearing weight on contralateral leg
patient stands with weight distributed equally over both feet, performs one tip toe exercise to document a decrease in calf VV
patient quickly resumes supine position, test leg elevated to empty veins
if finding abnormal, study repeated after tourniquiet applied to eliminate influences of superficial system
what is venous filing index
shows rate of venous refilling
calculated by using venous volume (VV) and venous filing time (VFT)
do you want venous filling index to be high or a low number?
low
what is ejection fraction?
measure calf muscle pump function
calculated using the ejection volume (EV) and functional venous volume (VV)
do you want ejection fraction to be a high or low number?
high %
what is residuall volume fraction (RVF)
is equivalent to ambulatory venous pressure in mmHg. calculated as the percentage of VV remaining after 10 tip toes movements
do you want residual volume fraction to be a high or low number
low %
