A prospective single-site case-controlled study comparing the microcirculatory stress response in the diabetic and non-diabetic foot using near infrared imaging

Introduction: As part of a thorough diabetic foot assessment, screening for limb perfusion to identify early -stage PAD is crucial. Although there is no ideal way to perform a non-invasive vascular study (NIVS), a variety of clinical options exist, but in patients with diabetes, these tests may be inaccurate. Thus, NIVS results can lead clinicians to falsely believe that sufficient perfusion in the diabetic foot is present.   The purpose of this study was to compare the microcirculatory response of patients without diabetes to patients with diabetic neuropathy after exposure to a series of controlled stresses. The primary objective was to demonstrate that the microcirculatory stress response is impaired in the diabetic neuropathic foot and Near-infrared spectroscopy (NIRS) is an effective tool allowing for the detection of these changes.Methods: This was a prospective single-site case-controlled one-visit study comparing the microcirculatory stress response in the diabetic and non-diabetic foot using NIRS in 20 subjects. After subject screening and consent, serial NIRS images were obtained on each subject after exposure of 5 minutes of individual stresses including heat (heating pad), cold (ice pack), elevation, and dependency to the right foot in a controlled environment.Results:This study did produce data illustrating an appreciable difference in the microcirculatory response to various stresses in subjects with and without diabetic neuropathy. Additionally, this pilot study supports the notion that the microcirculatory stress response is impaired in the diabetic neuropathic foot.Discussion: Endothelial dysfunction, derangements in numerous biochemical pathways, and autonomic neuropathy has been implicated as causes of microcirculation impairment in the diabetic neuropathic foot thus contributing to functional ischemia even in the presence of satisfactory blood flow under normal conditions. NIRS is a validated technology that has been successfully used to evaluate functional tissue oxygen saturation in the management of diabetic foot ulceration, but the results of this pilot study contribute to the idea that this imaging technology is also an effective tool for the detecting of changes within the microcirculatory system of the diabetic foot.References: