Laser Doppler velocimetry and platelet-derived growth factor as prognostic indicators for the healing of ulcers and ischaemic lesions of the lower limb

Abstract

The prognostic potential of skin blood flow measured by laser Doppler and serum platelet-derived growth factor (PDGF) levels was evaluated in patients with ischaemic lesions or ulceration of the lower limb. The laser Doppler-derived skin blood flow and perfusion pressure were measured in 93 patients with ischaemic lesions or ulceration in 98 lower limbs. Of these lesions, 61% healed spontaneously or with conservative local therapy, while 39% required major surgery. The likelihood for healing was reduced by older age. Comparison of receiver operating curves demonstrated that the optimal sensitivity and specificity were obtained for a combination of skin blood flow and perfusion pressure measured at 44 °C rather than at room temperature. If the skin perfusion pressure and blood flow were greater than 15mmHg and 100 U respectively at 44 °C, 91% lesions healed, while if they were less than these values none healed. This provided a sensitivity and specificity of 100% and 83% respectively. The serum PDGF concentration was measured by radioimmunoassay in 48 patients with ischaemic lesions or ulceration of the lower limb, and compared with that in 34 healthy controls and 15 patients who had undergone abdominal surgery 3–5 days previously. The median PDGF level in the control group (83pmol/l) was significantly less than that in the post-laparotomy group (217pmol/l). The median PDGF level in the 31 patients whose ulcers healed with conservative therapy (210pmol/l) was significantly higher compared with that in the 17 patients with unhealed ulcers (70pmol/l). This suggest that patients with non-healing ulcers may have an impaired ability to form PDGF and lends support to those studies that seek to improve ulcer healing by local application of exogenous PDGF. The use of these prognostic indices may facilitate the selection of therapeutic options in patients with ulceration or ischaemic lesions of the lower limb.