Utilization of NIRS for PAD Screening in a Wound Care Clinic

Introduction: Near-infrared spectroscopy (NIRS) with a provocative maneuver of leg elevation has shown promise in point of care detection of PAD in a wound care clinic. The provocative maneuver of leg elevation was added to avoid false positives in patients with CLI. The purpose of this study was to assess the viability of NIRS in conjunction with a transient leg elevation provocative maneuver for detecting severe PAD in patients with non-healing wounds. NIRS was also utilized to measure the response to treatment and response to revascularization. Ischemic patients with ulcers were revascularized and monitored.Methods:This retrospective observational cross-sectional study assessed 57 limbs in 34 patients receiving routine vascular screening for PAD at Madigan Army Medical Center. The patient limbs were stratified into normal (n = 17), mild (n = 9), moderate (n = 16), and severe (n = 15) PAD groups based on the clinician assessments. Additionally, the patients were assessed with NIRS measurements taken with the patient in the supine position at rest and using a provocative leg raise maneuver of transient leg elevation of 45° for 60 seconds.Results:The supine resting StO2 was not different between all four disease groups (P = .23). However, the decrease of ΔStO2 with transient leg elevation was significantly greater in the severe PAD group compared with the normal, mild, and moderate PAD groups (P  .002 for all). The leg elevation protocol was also used for two patients before and after lower limb revascularization, which demonstrated that the ΔStO2 corresponded with the clinical assessment of PAD severity. Resting supine NIRS images were unable to detect any differences among normal and limbs with different PAD severity. However, NIRS imaging with 45° leg elevation for 60 seconds showed a significant difference between severe PAD compared to healthy patients and those with mild to moderate PAD. This was used as evidence supporting the revascularization procedure.Discussion: These preliminary data support the use of NIRS and transient leg elevation as a point of care diagnostic tool to diagnose severe PAD that may impact wound healing. NIRS measurements with leg elevation might be a viable noninvasive, noncontact, and portable method of assessing severe PAD in patients with non-healing wounds. NIRS is a promising point of care technology for the diagnosis of critical limb ischemia but also can be used to measure the results of advanced wound care treatment and revascularization.References: