Predictive value of transcutaneous oximetry for selection of the amputation level

Background. Transcutaneous oximetry was studied to select the correct amput ation level for limb ischemic necrosis with possible identification of thre shold value. Methods. The method was evaluated in 30 cases (20 patients, 5 males and 15 females, of ages ranging from 61 to 93, average 73.1+/-8.5) where patients underwent amputation because of severe leg ischemia. Surgical operations we re: minor amputation (toe or transmetatarsal) in 23 cases, below knee amput ation in 7, Oxygen tension was measured at the dorsum foot and at the third superior of the anteromedial calf aspect. Results. Results were classified as success (primary or delayed healing) or failure (necrosis at the surgical wound). Amputation was successful in 17/ 30 cases with oxygen tension of 0-65 mmHg (mean 32.5+/-16.1) and failed in 13/30 with oxygen tension of 0-57 mmHg (mean 7.8+/-17.3), The difference wa s statistically significant (p=0.0004). Sensitivity of the method resulted 88.2%, specificity 84.6%, diagnostic accuracy 86.7%, positive predictive va lue 88.2% and negative predictive value 84.6%. A threshold of 20 mmHg was i dentified: 15/17 successful cases showed values greater than 20 mmHg, while 11/13 failed cases presented values lower than the threshold. Conclusions. Following our observations and according to some reported stud ies, we believe transcutaneous oximetry to be the best method for selection of amputation level This is a simple, noninvasive and accurate method, whi ch has showed itself superior to other techniques (i.e., Doppler and radioi sotope).