Confirmed Utility of Tissue Oxygen Saturation Assessments for Predicting Healing Capability in Below Knee Amputation

Tarig Barakat, Aminder Singh, Gerard Stansby, John Allen

Aim: Deciding amputation level can be clinically challenging. Visible light spectrophotometry tissue oxygen saturation (TOS) measurements can be used to help guide selection of lower limb amputation level assessment. These measurements are made at Freeman Hospital using the LEA O2C device, a portable vascular optical device for measuring tissue oxygen saturation in superficial tissue. The aim of this study was to evaluate the effectiveness of amputation level assessment using optical tissue oxygen saturation in predicting wound healing in those undergoing below knee amputations (BKA). Methods: A retrospective analysis of all patients who underwent amputation level assessment at a tertiary vascular unit between January 2009 and February 2017. All patients who underwent below knee amputations were included in the study (39 patients). Four patients were lost to follow up and 1 patient died before healing took place (in total 5). Results: 39 patients who underwent BKA were included in the study. 37 had long posterior flaps and 2 had skew flaps. Amputation level assessment (ALA) correctly predicted outcome of wound healing in 87% (34/39). Sensitivity of the test was for BKA assessment was 90% (95% confidence intervals [CI] 75%, 97%) and specificity 75% (CI 41%, 96%). Positive predictive value, i.e. a BKA would heal, was 93% (CI 79%, 99%) and negative predictive value 67% (CI 35%,88%). The likelihood ratio is 3.6. Three BKAs were converted to above knee amputation. The conversion rate from BKA to AKA was < 10%. Conclusion: ALA is a good tool in predicting wound healing in patients undergoing major limb amputation. It gives the clinician an objective assessment and assist in decision making on level of amputation especially on borderline cases.