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

Background: Spinal cord stimulation (SCS) improves microcirculatory blood f low, relieves ischemic pain and reduces amputation rate in patients with se vere peripheral arterial occlusive disease. Aim: To evaluate the transcutaneous oxygen tension (TcPO2) measurements as a specific prognostic parameter in the prediction for permanent device impl antation in a prospective controlled study in patients with lower limb isch emia. Methods: 45 patients (35 men, 10 women; mean age 65 years, range: 46-70 yea rs) were submitted to implantation of a spinal cord electrical generator fo r rest pain, trophic lesions dry gangrene in severe lower limb ischemia, af ter failed conservative or surgical treatment The clinical status was class ified as Fontaine's stages III and IV and the main pathology was essentiall y due to atherosclerosis and diabetic vascular disease. Pedal transcutaneou s 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 rel ief > 50% and limb salvage was obtained for at least 6 months. In 10 patien ts, the method failed and the patients' limbs were amputated. TcPO2 was ass essed on the dorsum of the foot. Clinical improvement and SCS success was a ssociated with an increase of TcPO2, within the first 2 weeks after implant ation (temporary period). Limb salvage was achieved in those patients who p resented 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 cm(2), and in those with trophic lesions > 3 cm(2), 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 fo r severe critical lower limb ischemia, the SCS increases the skin blood flo w, is associated with a significant pain relief and could prove an excellen t alternative therapy that improves the quality of life. We also demonstrat e that TcPO2 increase within a test period of 2 weeks, is a predictive inde x of SCS therapy success and should be considered in terms of cost effect b efore the final decision for permanent implantation.