Transcutaneous fluorescence spectroscopy as a tool for non-invasive monitoring of gut function: first clinical experiences

Abstract

Gastro-intestinal function plays a vital role in conditions ranging from inflammatory bowel disease and HIV through to sepsis and malnutrition. However, the techniques that are currently used to assess gut function are either highly invasive or unreliable. Here we present an alternative, non-invasive sensing modality for assessment of gut function based on fluorescence spectroscopy. In this approach, patients receive an oral dose of a fluorescent contrast agent and a fibre-optic probe is used to make fluorescence measurements through the skin. This provides a readout of the degree to which fluorescent dyes have permeated from the gut into the blood stream. We present preliminary results from our first measurements in human volunteers demonstrating the potential of the technique for non-invasive monitoring of multiple aspects of gastro-intestinal health.

Understanding the role of the gut in undernutrition: what can technology tell us?

“…A preliminary demonstration of this approach has been reported in rats, 60 and human validation is currently under way. 61 However, development of a handheld/wearable device that is suitable for POC deployment is still required.…”

“…This technique is comparable in concept to previous studies performed in animals [58][59][60] and is currently being validated in humans. 61 Briefly, it involves patients drinking an oral dose of a fluorescent contrast agent (dye) and a wearable sensor or probe being used to detect and quantify the uptake of the contrast agent from the gut into the bloodstream. As the rate and degree of uptake are affected by changes in permeability, this approach will potentially allow rapid, non-invasive assessment of intestinal permeability, without the need to collect urine samples.…”

“…A preliminary demonstration of this approach has been reported in rats, 60 and human validation is currently under way. 61 However, development of a handheld/wearable device that is suitable for POC deployment is still required. Raman spectroscopy has the potential to provide advanced information across a number of domains of gut dysfunction (eg, assessment of the microbiota, quantification of bacterial translocation and analysis of breath samples).…”

The contribution of environmental enteropathy to the global problem of micronutrient deficiency

“…Another prominent feature of EE is the increased permeability referred to earlier, which over the past 40 years has been most extensively studied using lactulose permeation (30,57) . More recent studies have used fluorescein as a marker of the leakiness of the mucosa, either by showing leakage of fluorescein from the systemic circulation into the gut lumen during endoscopy (52,58) , or by showing leakage of oral fluorescein into the systemic circulation (59,60) . In an ingenious approach, transcriptomic analysis of shed enterocytes in stool samples identified mucin and inflammatory genes associated with EE in an entirely non-invasive way (61) .…”

Analysis of muscle tissue in vivo using fiber-optic autofluorescence and diffuse reflectance spectroscopy

“…A current barrier to widespread use of this technique is a lack of economical, accessible, and easy-to-use platforms that integrate AF/DR spectroscopy with relevant and easily interpretable spectral analyses. In principle, such an approach is feasible and supported by a range of studies characterizing tissue AF in the gut, arteries, and myocardium 29 – 31 and in tumors. 32 – 35 AF spectroscopy has also been employed in conjunction with DR spectroscopy in a range of settings.…”