Transcutaneous oxygen tension (TcPO2) in the testing period of spinal cord stimulation (SCS) in critical limb ischemia of the lower extremities

Abstract

Background: Spinal cord stimulation (SCS) improves microcirculatory blood flow, relieves ischemic pain and reduces amputation rate in patients with severe peripheral arterial occlusive disease.

Aim: To evaluate the transcutaneous oxygen tension (TcPO2) measurements as a specific prognostic parameter in the prediction for permanent device implantation in a prospective controlled study in patients with lower limb ischemia.

Methods: 45 patients (35 men, 10 women; mean age 65 years, range: 46-70 years) were submitted to implantation of a spinal cord electrical generator for rest pain, trophic lesions dry gangrene in severe lower limb ischemia, after failed conservative or surgical treatment. The clinical status was classified as Fontaine's stages III and IV and the main pathology was essentially due to atherosclerosis and diabetic vascular disease. Pedal transcutaneous oxygen tension (TcPO2), ankle and toe pressure Doppler measurements were performed before, 2 weeks and 4 weeks after implantation.

Results: After 18 months follow-up, pain relief was > 75% and limb salvage was achieved in 26 patients. In 9 patients, a partial success with pain relief > 50% and limb salvage was obtained for at least 6 months. In 10 patients, the method failed, and the patients' limbs were amputated. TcPO2 was assessed on the dorsum of the foot. Clinical improvement and SCS success was associated with an increase of TcPO2, within the first 2 weeks after implantation (temporary period). Limb salvage was achieved in those patients who presented significant TcPO2 increase within the first 2 weeks of the testing period (from 21.6 mmHg to 29.5 mmHg in the patients with rest pain, P = 0.035, from 15.2 mmHg to 21.1 mmHg, P = 0.035 in those with trophic lesions < 3 cm2, and in those with trophic lesions > 3 cm2, from 12.4 mmHg to 17.3 mmHg) independently of the stage of the disease and of the initial TcPO2 value. TcPO2 changes were related to the presence of adequate paresthesias and warmth in the painful area during the trial period. The systolic ankle/brachial blood pressure index did not change under stimulation.

Conclusions: In patients with failed conservative and surgical treatment for severe critical lower limb ischemia, the SCS increases the skin blood flow, is associated with a significant pain relief and could prove an excellent alternative therapy that improves the quality of life. We also demonstrate that TcPO2 increase within a test period of 2 weeks, is a predictive index of SCS therapy success and should be considered in terms of cost effect before the final decision for permanent implantation.