The Association Between pH and Fluorescence as Noninvasive Diagnostic Tools in Chronic Wounds

Abstract

MolecuLight i:X is a noninvasive, portable device that captures images, measures wound areas, and allows the evaluation of the bacterial environment in real time. The aim of the study was to correlate the different fluorescence (light green, red, cyan) and dark red–purple–black color areas with average pH values in these areas and with average wound bed score (WBS). During a 4-week period, we enrolled 43 adult patients (23 females and 20 males) with clinically infected and uninfected chronic ulcers. In our study, the mean age was 68 years old. The etiologies were 21 venous ulcers, 3 arterial ulcers, 4 vasculitis, 7 pyoderma gangrenosum, 7 traumatic ulcers, and 1 neoplastic ulcer. The average area was 16.92 cm2 and the average WBS was 9.17. A total of 16 ulcers (37%) were positive for clinical signs and symptoms of infection and 27 ulcers were negative (63%). Thirty-six ulcers emitted a single fluorescence: cyan (n = 13), red (n = 1), light green (n = 14), and dark red-purple–black (n = 8). Six wounds showed a double fluorescence area: red and cyan (n = 1) and cyan and light green (n = 5). One ulcer emitted a triple fluorescence area: red, cyan, and light green. Overall in 43 ulcers, we found 43 fluorescence and 8 dark red–purple–black color. We found significant data between pH and fluorescence. pH values on wound bed confirm in a noninvasive way the correlation between fluorescence and bacterial burden. Moreover, MolecuLight i:X is able to detect objectively the bacterial proliferation, in contrast with pH which cannot distinguish different types of bacteria.

The Role of Autoflorescence Imaging Device in the Evaluation of Bacteria Burden Control

“…23 Janowska et al found significant correlation between higher pH and increased bacteria fluorescence. 24 In a retrospective cohort study that reported more than 150,000 patients with over 300,000 diabetic and vascular wounds, it was demonstrated that the more frequent debridement has an outcome in terms of healing and reduction of colonization or infection. 25 Various types of dressings such as silver dressings, 26 binding bacteria dressings, 27 iodine dressings, honey dressings, 28 hyperoxidized oil 29 and polyhexamethylene biguanide dressings 30 have been used locally to reduce bacterial load.…”

A Host-Directed Approach to the Detection of Infection in Hard-to-Heal Wounds

“…An alternative non-invasive approach is imaging, either thermal or ultraviolet. Multi-spectral analysis has the potential to track size, general biochemical markers, and fluorescent metabolites [ 67 ]. Imaging relies on powerful fluor- and chromophores produced by infecting organisms.…”