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 (700–1000？nm) to monitor tissue oxygenation and haemodynamics transcutaneously by measuring changes in chromophore concentration in the microcirculation (oxygenated [O2Hb] and deoxygenated [HHb] haemoglobin) [1–4]. These changes (expressed as μmol/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
References
[1]
M. Ferrari, L. Mottola, and V. Quaresima, “Principles, techniques, and limitations of near infrared spectroscopy,” Canadian Journal of Applied Physiology, vol. 29, no. 4, pp. 463–487, 2004.
[2]
T. Hamaoka, K. K. McCully, V. Quaresima, K. Yamamoto, and B. Chance, “Near-infrared spectroscopy/imaging for monitoring muscle oxygenation and oxidative metabolism in healthy and diseased humans,” Journal of Biomedical Optics, vol. 12, no. 6, Article ID 062105, 2007.
[3]
M. Wolf, M. Ferrari, and V. Quaresima, “Progress of near-infrared spectroscopy and topography for brain and muscle clinical applications,” Journal of Biomedical Optics, vol. 12, no. 6, Article ID 062104, 2007.
[4]
A. J. Macnab, “Biomedical applications of near infrared spectroscopy,” in Biological and Biomedical Spectroscopy, A. Barth and P. Haris, Eds., vol. 2 of Advances in Biomedical Spectroscopy, pp. 305–402, IOS Press, Amsterdam, The Netherlands, 2009.
[5]
R. Boushel, H. Langberg, J. Olesen, J. Gonzales-Alonzo, J. Bülow, and M. Kj？r, “Monitoring tissue oxygen availability with near infrared spectroscopy (NIRS) in health and disease,” Scandinavian Journal of Medicine and Science in Sports, vol. 11, no. 4, pp. 213–222, 2001.
[6]
M. C. P. van Beekvelt, B. G. M. van Engelen, R. A. Wevers, and W. N. J. M. Colier, “In vivo quantitative near-infrared spectroscopy in skeletal muscle during incremental isometric handgrip exercise,” Clinical Physiology and Functional Imaging, vol. 22, no. 3, pp. 210–217, 2002.
[7]
L. Stothers, B. Shadgan, and A. Macnab, “Urological applications of near infrared spectroscopy,” The Canadian Journal of Urology, vol. 15, no. 6, pp. 4399–4409, 2008.
[8]
A. J. Macnab and L. Stothers, “Near-infrared spectroscopy: validation of bladder-outlet obstruction assessment using non-invasive parameters,” The Canadian Journal of Urology, vol. 15, no. 5, pp. 4241–4248, 2008.
[9]
L. Stothers, R. Guevara, and A. J. Macnab, “Classification of male lower urinary tract symptoms using mathematical modeling and a regression tree algorithm of non-invasive near infrared spectroscopy parameters,” European Urology, vol. 57, no. 2, pp. 327–333, 2009.
[10]
A. Te, D. E. Chung, R. I. Lee, and S. A. Kaplan, “Near infrared spectroscopy (NIRS) for application in urology,” The Journal of Urology, vol. 181, no. 4, p. 601, 2009.
[11]
R. N. Pittman, “Oxygen supply to contracting skeletal muscle at the microcirculatory level: diffusion vs. convection,” Acta Physiologica Scandinavica, vol. 168, no. 4, pp. 593–602, 2000.
[12]
C. G. Ellis, J. Jagger, and M. Sharpe, “The microcirculation as a functional system,” Critical Care, vol. 9, no. 4, pp. S3–S8, 2005.
[13]
S. S. Segal, “Regulation of blood flow in the microcirculation,” Microcirculation, vol. 12, no. 1, pp. 33–45, 2005.
[14]
A. F. Brading, J. E. Greenland, I. W. Mills, G. McMurray, and S. Symes, “Blood supply to the bladder during filling,” Scandinavian Journal of Urology and Nephrology, Supplement, vol. 33, no. 201, pp. 25–31, 1999.
[15]
R. T. Kershen, K. M. Azadzoi, and M. B. Siroky, “Blood flow, pressure and compliance in the male human bladder,” The Journal of Urology, vol. 168, no. 1, pp. 121–125, 2002.
[16]
A. T. L. Lin, M. T. Chen, C. H. Yang, and L. S. Chang, “Blood flow of the urinary bladder: effects of outlet obstruction and correlation with bioenergetic metabolism,” Neurourology and Urodynamics, vol. 14, no. 3, pp. 285–292, 1995.
[17]
A. Belenky, Y. Abarbanel, M. Cohen, O. Yossepowitch, P. M. Livne, and G. N. Bachar, “Detrusor resistive index evaluated by Doppler ultrasonography as a potential indicator of bladder outlet obstruction,” Urology, vol. 62, no. 4, pp. 647–650, 2003.
[18]
R. Kozlowski, M. B. Siroky, R. J. Krane, and K. M. Azadzoi, “Regulation of blood flow and microcirculation resistance in rabbit bladder,” The Journal of Urology, vol. 168, no. 4, pp. 1608–1614, 2002.
[19]
L. Stothers, A. J. Macnab, and B. Shadgan, “Detection of hypoxia within the detrusor using near infrared spectroscopy (NIRS),” The Journal of Urology, vol. 181, no. 4, p. 600, 2009.
[20]
A. J. Macnab, L. Stothers, and B. Shadgan, “Wireless near-infrared spectroscopy (NIRS) of the bladder detrusor during uroflow in ambulant children and adults,” The Journal of Urology, vol. 181, no. 4, pp. 600–601, 2009.
[21]
A. J. Macnab and L. Stothers, “Development of a near-infrared spectroscopy instrument for applications in urology,” The Canadian Journal of Urology, vol. 15, no. 5, pp. 4233–4240, 2008.
[22]
M. C. Van der Sluijs, W. N. J. M. Colier, R. J. F. Houston, and B. Oeseburg, “A new and highly sensitive continuous wave near infrared spectrophotometer with multiple detectors,” in Proceedings of Photon Propagation in Tissues III, vol. 3194 of Proceedings of SPIE, San Remo, Italy, September 1997.
[23]
B. Shadgan, W. D. Reid, R. Gharakhanlou, L. Stothers, and A. J. MacNab, “Wireless near-infrared spectroscopy of skeletal muscle oxygenation and hemodynamics during exercise and ischemia,” Spectroscopy, vol. 23, no. 5-6, pp. 233–241, 2009.
[24]
B. Shadgan, K. Afshar, L. Stothers, and A. Macnab, “Near-infrared spectroscopy of the bladder: a new technique for studying lower urinary tract function in health and disease,” in Photonic Therapeutics and Diagnostics VI, vol. 7548 of Proceedings of SPIE, San Francisco, Calif, USA, January 2010.
[25]
K. Afshar, A. Mirbagheri, H. Scott, and A. E. MacNeily, “Development of a symptom score for dysfunctional elimination syndrome,” The Journal of Urology, vol. 182, no. 4, supplement, pp. 1939–1943, 2009.
[26]
M. Ferrari, T. Binzoni, and V. Quaresima, “Oxidative metabolism in muscle,” Philosophical Transactions of the Royal Society B: Biological Sciences, vol. 352, no. 1354, pp. 677–683, 1997.
[27]
Y. N. Bhambhani, “Muscle oxygenation trends during dynamic exercise measured by near infrared spectroscopy,” Canadian Journal of Applied Physiology, vol. 29, no. 4, pp. 504–523, 2004.
[28]
V. Quaresima, R. Lepanto, and M. Ferrari, “The use of near infrared spectroscopy in sports medicine,” Journal of Sports Medicine and Physical Fitness, vol. 43, no. 1, pp. 1–13, 2003.
[29]
G. Murthy, A. R. Hargens, S. Lehman, and D. M. Rempel, “Ischemia causes muscle fatigue,” Journal of Orthopaedic Research, vol. 19, no. 3, pp. 436–440, 2001.
[30]
M. C. P. van Beekvelt, K. Orbon, B. G. M. Van Engelen, R. A. Wevers, and W. N. J. M. Colier, “NIR spectroscopic measurement of local muscle metabolism during rhythmic, sustained and intermittent handgrip exercise,” in Photon Migration and Diffuse-Light Imaging, vol. 5138 of Proceedings of SPIE, Munich, Germany, June 2003.
[31]
X. Game, E. Chartier-Kastler, and A. Ruffion, “Lower urinary tract dysfunction and non-neurogenic neurogenic bladder or “dysfunctional voiding”,” Progres en Urologie, vol. 17, no. 3, pp. 406–414, 2007.
