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

OBJECTIVE: 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).

DESIGN: Prospective single-center observational study.

SETTING: University-based rehabilitation center.

PARTICIPANTS: 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).

INTERVENTIONS: Not applicable.

MAIN OUTCOME MEASURES: 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).

RESULTS: 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.

CONCLUSIONS: 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.