AMPUTATION LEVEL ASSESSMENT USING LIGHTGUIDE SPECTROPHOTOMETRY

The aim of this experimental study was to investigate whether lightgui de spectrophotometry in the visible wavelength range in skin could be used to predict stump healing viability in patients with critical lowe r limb ischaemia. Remission spectra recorded at two sites (medial and lateral) on the line of a proposed trans-tibial amputation (TTA) and a t 10mm intervals along the leg were analysed to give haemoglobin oxyge nation (SO2). Degree of tissue hypoxia (DTH) along the leg was defined as the percentage of values along the leg less than 10% SOz. DTH and mean SO2 values were compared with skin blood flow values ((I-125) 4-I odoantipyrine clearance technique) and clinical outcome of trans-tibia l amputation, (TTA) or trans-femoral amputation (TFA), in 41 patients. SO2 histograms were also measured in 12 normal subjects for compariso n. The results of the study allowed the establishment of criteria for the accurate prediction of flap healing potential. Successful TTAs all displayed a minimum mean SO2 at the medial and lateral measurement si tes of 30%, together with a maximum degree of tissue hypoxia of 15% al ong the limb. The combination of these criteria gave a sensitivity and selectivity of 1.0 for prediction of a successful outcome of TTA.