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Overview :
Doppler velocimetry can be used before below the knee
amputation to predict if the operative wound will heal. Moving red blood cells
in blood vessels cause a doppler shift of incident light which correlates with
the velocity of blood flow.
Procedure:
• laser
doppler velocimeter is used to measure cutaneous blood flow in study region
•
continuous and noninvasive
Sites tested:
(1) anterior calf
(2) posterior calf
(3) upper arm
critical calf reading in mV =
= minimum (anterior calf reading in mV, posterior calf
reading in mV)
calf-to-brachial index =
= (critical calf reading in mV) / (upper arm reading in
mV)
Interpretation:
• If both
the anterior or posterior calf reading is >= 20 mV, then the wound will heal
in most (96%) patients.
• If either
the anterior or posterior calf reading is < 20 mV, then the wound will
probably not heal.
• The
calf-to-brachial index does not offer more accuracy than the critical calf
reading, but wounds that failed to heal show a lower index.
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