Is colour duplex imaging possible through hydrocolloid dressings?
Colour flow duplex scanning is an accepted method of determining the patency and haemodynamic status in infrainguinal grafts and native arteries. There are often dressings covering the leg above the vessel to be scanned. A blinded study compared scanning normal superficial femoral arteries with scans when one of five commonly used dressings were applied to the skin above the artery, in random order. The blinded operator graded the signal produced on a linear analogue scale. An absorbent material dressing and a bilaminate membrane dressing did not transmit ultra-sound at all. Two thin membrane dressings allowed excellent B-mode and colour flow images, in addition to clear Doppler signals. A thin hydrocolloid allowed a clear B-mode image of each artery to be visualised and an adequate Doppler waveform to be obtained. However colour flow mapping was less than optimal although it was possible in each of the arteries. In patients who require dressings and who may require colour flow duplex
