The value of toe pulse waves in determination of risks for limb amputation and death in patients with peripheral arterial disease and skin ulcers or gangrene

Objectives: The purpose of this study was to determine whether the presence of low amplitude of pulse waves recorded from the toes is related to the risk of subsequent amputation and death in patients with skin ulcers or gangrene and peripheral arterial disease, and how the risk of low wave amplitude relates to the risk associated with low peripheral pressures. Methods: A total of 309 patients with 346 limbs with skin lesions and arterial disease referred to the vascular laboratory were followed up for an average of 5 years (range, 1-8 years). Measurements were carried out to obtain ankle and toe pressures, pressure indices, and toe pulse wave amplitude. These variables were related to the risks of major amputation and total and cardiovascular death by means of the Cox proportional hazards model. Results: Low toe pulse wave amplitude (less than or equal to 4 mm) was associated with increased risk of amputation (relative risks 4.20 in all limbs and 2.63 in those with toe pressure less than or equal to 30 mm Hg; P < .01). Wave amplitude remained significantly associated with increased risk of amputation after controlling for each pressure variable (P < .01). Low pulse wave amplitude and toe/brachial index were associated with increased risks of both total and cardiovascular death in all patients (relative risks ranged from 1.43-1.73; P < .05) and in those with toe pressure of 30 mm Hg or less (relative risks 1.56-1.90; p < .05). Conclusions: Low toe pulse wave amplitude is related significantly to increased risks of amputation and death in patients with skin lesions and arterial disease. The presence of low wave amplitude provides significant information in addition to peripheral pressures with respect to the risk of amputation.