Determination of amputation level in ischaemic limbs using tcPO2 measurement

Abstract

Background: Determination of the optimal amputation level is essential for patients, morbidity and rehabilitation. Various non-invasive procedures have been proposed to determine the optimal level of amputation. There is no consensus on the minimal tcPO2 level that is required to predict the healing of the stump. Therefore we aimed to rank the probability of primary wound healing at the most distal level and to answer the question if there is a lower limit of tcPO2 below which healing cannot occur. Patients and methods: 56 consecutive patients undergoing amputation below the knee for ischaemic gangrene of limbs were prospectively enrolled in the study. 39 were men (18 of whom were diabetics) and 17 women (8 diabetics) whose ages ranged from 45 to 87 years (mean 73 years). The total of 71 amputations was performed on the 56 patients: 39 below-knee with primary healing and, in 16 patients the above-knee reamputation was performed, due to the non-healing wound on the below-knee stump. The level of the amputation (below or above the knee) was in all cases decided solely on clinical grounds. TcPO2 was measured on each patient prior to amputation, on the dorsum of the foot and 10 cm below the knee. Results: The median tcPO2 value on the dorsum of the foot of diseased legs before amputation was 12 mm Hg (range from 0 to 22 mm Hg). At the anticipated level of the amputation of the shank, the median value of tcPO2 was 28 mm Hg (8–56 mm Hg). Patients with primary healing of postoperative wounds had significantly higher values of tcPO2 than patients with failure to heal (37mm Hg; range15–56mm Hg vs.18 mm Hg; range 8–36 mm Hg, p < 0.01). The success rate increased with higher tcPO2 values at the level of amputation. The 15% prevalence of reamputations was obtained for tcPO2 values between 25 and 36 mm Hg (median value 33 mm Hg) and the threshold value of tcPO2 below which the stump failed to heal was 15 mm Hg. Conclusions: Our study showed that tcPO2 is a reliable indicator of local ischemia. The integration of this parameter with other personal clinical criteria may be a valuable help to the surgeon in decision making.