Validation of a Non-invasive Imaging Photoplethysmography Device to Assess Plantar Skin Perfusion in Comparison with Laser Speckle Contrast Analysis.

Assessing skin perfusion is an established and reliable method to study impaired
5 lower limb blood flow. Laser Speckle Contrast Analysis (LASCA) has been
6 identified as the current gold standard to measure skin perfusion. Imaging
7 photoplethysmography (iPPG) is a new low-cost imaging technique to assess
8 perfusion. However, it is unclear how results obtained from this technique compare
9 against that of LASCA at plantar skin. Therefore, the aim was to investigate the
10 association between the skin perfusion at the plantar surface of the foot using iPPG
11 and LASCA. Perfusion at six plantar locations (Hallux, 1st 3rd 5th metatarsal
12 heads, midfoot, heel) was simultaneously measures using LASCA and iPPG in 20
13 healthy participants. Skin thickness and skin temperature were also collected at the
14 same plantar locations. Spearman’s rank tests showed significant associations with
15 medium strength between the perfusion values measured with LASCA and iPPG
16 for most tested sites. No improvement in the relationship between iPPG and
17 LASCA data was observed when controlling for either skin thickness or skin
18 temperature. Skin perfusion values obtained using iPPG were found to be
19 significantly associated with the corresponding values obtained using the gold
20 standard LASCA device. Additionally, the measurement of perfusion using iPPG
21 is shown to be robust.