Microcirculatory Assessment of Arterial Below-Knee Stumps: Near-Infrared Spectroscopy Versus Transcutaneous Oxygen Tension-A Preliminary Study in Prosthesis Users.

Abstract

To examine metrologic properties of near-infrared spectroscopy (NIRS) versus transcutaneous oxygen tension (TcPO₂) for microcirculatory assessment of vascular transtibial stumps at the stabilized period of prosthesis fitting, as a preliminary step before exploring its ability to predict stump healing, considering the previously identified limits of TcPO₂ (borderline area between 15 and 35mmHg). Prospective single-center observational study. University-based rehabilitation center. Individuals with unilateral transtibial amputation for peripheral artery disease, at the definitive stage of prosthesis fitting, able to perform a 2-minute walk test (N=30). Not applicable. Test-retest, with the stump being evaluated in supine and inclined positions, first by NIRS (tissue saturation index [TSI], oxyhemoglobin, deoxyhemoglobin, and total hemoglobin) and second by TcPO₂. Subjects carried out a 2-minute walk test and visual analog scales (wound healing and pain). Feasibility and tolerance of NIRS were satisfactory. The reliability of NIRS and TcPO₂ values was good (intraclass correlation coefficient >0.7; P<.05). No significant relation was found between NIRS and TcPO₂. No responsiveness (inclined vs supine) was reported (P>.05). A significant relation between TSI and the 2-minute walk test (r>.49, P<.05) was found. NIRS is painless, complication-free, and feasible, with good reliability. NIRS evaluates others domain than TcPO₂ that are more linked to metabolic adaptation. Its capacity to predict stump healing and tolerance to early prosthesis fitting is therefore interesting to estimate in future studies.