Significance of Transcutaneous Spectrophotometric Oxygen Measurement Using Oxygen to See (O2C®) in Major Lower Extremity Amputations

Major amputation is unavoidable if revascularization is not possible in critical limb ischemia with nonviable limb. Good perfusion is imperative to achieve uneventful wound healing. This case series analysis evaluated the use of laser Doppler flowmeter and tissue spectrometer (O2C®) in assessing tissue perfusion before and after a major lower limb amputation. Forty patients with an indication for a major lower limb amputation were from March 2018 to January 2020 recruited. O2C® measurement was performed at pre-defined points along the transection line and at pre-designated points of reference before and after surgery. Analysis of variance was carried out for repeated measurements. The correlation of three different O2C® parameters with wound healing was analyzed. After exclusion of 3 patients, 37 patients remained for evaluation. Twenty-three patients (62%) had uneventful wound healing, 9 patients (24%) had a minor healing disorder, whereas 5 patients (14%) needed surgical re-intervention. Few correlations between the O2C® parameters and wound healing could be demonstrated. These included the preoperative oxygen saturation in the thigh area before a thigh amputation (p = 0.0157). The blood flow rate correlated with wound healing on the thigh preoperatively during knee disarticulation (p = 0.0349). Marked variability in the measured values over various points in time was noted. With the exception of the oxygen saturation and flow parameter on the thigh, none of the other O2C measurements predicted wound healing after a major lower limb amputation. O2C® is of minor value to assess tissue perfusion before a major limb amputation.