%0 Journal Article
%T Near-Infrared Spectroscopy of the Bladder: New Parameters for Evaluating Voiding Dysfunction
%A Andrew Macnab
%A Babak Shadgan
%A Kourosh Afshar
%A Lynn Stothers
%J International Journal of Spectroscopy
%D 2011
%I Hindawi Publishing Corporation
%R 10.1155/2011/814179
%X We describe innovative methodology for monitoring alterations in bladder oxygenation and haemodynamics in humans using near-infrared spectroscopy (NIRS). Concentrations of the chromophores oxygenated (O2Hb) and deoxygenated (HHb) haemoglobin and their sum (total haemoglobin) differ during bladder contraction in health and disease. A wireless device that incorporates three paired light emitting diodes (wavelengths 760 and 850 nanometers) and silicon photodiode detector collects data transcutaneously (10£¿Hz) with the emitter/detector over the bladder during spontaneous bladder emptying. Data analysis indicates comparable patterns of change in chromophore concentration in healthy children and adults (positive trend during voiding, predominantly due to elevated O2Hb), but different changes in symptomatic subjects with characteristic chromophore patterns identified for voiding dysfunction due to specific pathophysiologies: bladder outlet obstruction (males), overactive bladder (females), and nonneurogenic dysfunction (children). Comparison with NIRS muscle data suggests altered bladder haemodynamics and/or oxygenation may underlie voiding dysfunction offering new insight into the causal physiology. 1. Introduction Near-infrared spectroscopy (NIRS) is an established noninvasive optical technique, which uses light in the near-infrared (NIR) spectrum (700¨C1000£¿nm) to monitor tissue oxygenation and haemodynamics transcutaneously by measuring changes in chromophore concentration in the microcirculation (oxygenated [O2Hb] and deoxygenated [HHb] haemoglobin) [1¨C4]. These changes (expressed as ¦Ìmol/100£¿mL) are measured in real-time as a change relative to baseline. Changes in total haemoglobin concentration [tHb] (the sum of [O2Hb] and [HHb]) indicate change in blood volume [5, 6]. The physics principles underlying this technology, the wide range of research using NIRS [1, 3, 4], and the NIRS-derived parameters with validated methods of measurement [3] have been comprehensively described. However, urological applications are recent, and NIRS monitoring of the bladder (detrusor muscle) is a novel use of NIRS, and a disruptive technology in the context of the evaluation of voiding dysfunction, as a noninvasive measure of changes in oxygenation and haemodynamics during voiding is now feasible. The evolution and technical aspects of NIRS use in urology have been reviewed [4, 7]; evidence is accumulating that the patterns of change in [O2Hb], [HHb], and [tHb] observed in the bladder microcirculation during the voiding cycle differ in health and disease, and algorithms
%U http://www.hindawi.com/journals/ijs/2011/814179/