Quantifying dermal microcirculatory changes of neuropathic and neuro ischemic diabetic foot ulcers using spatial frequency domain imaging: a shade of things to come?
It is necessary to assess lower extremity ulceration and amputation risk by non-invasive vascular and perfusion diagnostics in diabetic patients. The spatial frequency domain imaging (SFDI) is a non-contact, optical imaging technique used to identify distinct microcirculatory changes and oxygenation that appears before neuropathic and neuroischemic wounds. This method can identify sites at risk of ulceration before clinically identifiable signs. The author Murphy and colleagues published a study in “BMJ journals” under the title “Quantifying dermal microcirculatory changes of neuropathic and neuroischemic diabetic foot ulcers using spatial frequency domain imaging: a shade of things to come?” The summary of the study is below:
Objectives:
To investigate pre-ulcerative changes in dermal microcirculation and oxygenation for ulcers of different aetiology using SFDI
Method:
The study includes 35 patients with diabetes mellitus and a history of diabetic foot ulceration. These patients underwent imaging with SFDI monthly. There was a selection of two ulcerated patients within the year-long longitudinal study, for the presentation of their clinical course along with the dermal microcirculation biomarkers from SFDI.
Findings:
There are two categories of wounds, Neuropathic or neuroischemic. The differing pathological processes, of wounds, can be detected by SFDI biomarkers. The study observed an increase in StO2 and a decrease in HbT1 in DM patients 91 days before the ulceration of the first patient’s right second metatarsal phalangeal joint (MTPJ). Hence, an increase in StO2 and a decrease in HbT1 might be a signal for at-risk sites. It can also serve as a marker of dermal microcirculation dysfunction within the papillary dermis. On other hand, the combination of low StO2 with increased HbT1 and HbT2 (observed in the 2nd patient around 9 weeks before ulceration) may signify the pooling of deoxy-Hb in the dermal microcirculation.
Hence, SFDI can be effective in identifying patients at risk of ulceration with microcirculatory changes. As patients with diabetic foot ulcers are observed to have an impaired skin vasodilatory response to lower extremity heating, pressure, ischemia-induced reactive hyperemia, and acetylcholine administration in comparison to non-ulcer patients with diabetes and healthy controls.
Limitations:
Investigators acknowledge not using the classification and analysis of wounds by specific aetiology for neuropathic and neuroischemic wounds. Additionally, fewer wounds were investigated.
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