Affiliations: [a] NIRS Study Group, Department of Urologic Sciences, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada | [b] Center for Collaboration on Repair Discoveries, University of British Columbia, Vancouver, BC, Canada | [c] Department of Electrical and Computer Engineering, University of British Columbia, Vancouver, BC, Canada
Correspondence:
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Corresponding author: Andrew J. Macnab, Room C234, BC’s Children’s and Women’s Hospital, 4500 Oak Street, Vancouver, BC, Canada, V6H 3N1. Tel.: +1 604 875 2850; Fax: +1 604 875 2530; E-mail: amacnab@cw.bc.ca.
Abstract: While adequate photon migration through the tissue of interest is essential for near infrared spectroscopy (NIRS), the initial transmission of sufficient photons transcutaneously and ultimate capture of as many as possible returning from the interrogated tissue is also a requisite. Hence the relevance of both the interface between the emitter detector array of a NIRS instrument and the characteristics of the skin through which photons must migrate. We describe design components incorporated into a continuous wave NIRS instrument developed to monitor the bladder transcutaneously in subjects in rural African clinics; review the relevance and impact of melanin pigmentation, cutaneous hair and skin composition on photon migration; and report the results of pilot testing. Sufficient photon transmission was achieved to transcutaneously monitor changes in chromophore concentration in the bladder effectively in darkly pigmented subjects during spontaneous voiding. We also confirmed the importance of a new protocol to optimize device positioning over the bladder and employing measures to avoid signal contamination caused by pubic hair; both enhance the quality of chromophore data.
