Colour Duplex imaging through wound dressings

Abstract

Colour flow Duplex scanning is becoming the method of choice to determine patency and haemodynamic status in infrainguinal grafts and native arteries. Due to surgical wounds and ulcers, there are often dressings covering the leg above the vessel to be scanned. There is no data as to the effect of different wound dressings on colour flow Duplex signals. Ten normal superficial femoral arteries were scanned by a blinded operator. Initially the artery was visualised to assess the normal image produced for each artery on B-mode and colour flow ultrasound and a Doppler reading was taken. Then each of five commonly used dressings were applied to the skin above the artery, in random order and the blinded operator graded the signal produced on a linear analogue scale. Primapore, an absorbent material dressing and Spyroflex, a bilaminate membrane dressing, did not transmit ultra-sound at all. Granuflex extra thin 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. Opsite and Tegaderm, two thin membrane dressings allowed excellent B-mode and colour flow images, in addition to clear Doppler signals. In patients who require dressings and who may require colour flow Duplex scanning of vessels in the same area, we would suggest the use of a product that permits ultrasound transmission, thus saving the necessity of removing the dressing for the assessment.