Background: Spinal cord injury (SCI) compromises bladder function, including the ability to sense the need to void. Overdistension leads to involuntary leakage and endangers health through upper renal tract pressure damage and autonomic dysreflexia. A monitor warning the bladder is full will allow optimal use of manual expression or intermittent catheterization. Methods: The wearable interface is a silicone sheet worn over the bladder, which incorporates a grid of 4 near-infrared LED transmitters with 3 wavelengths (2 at 950 nm for water detection and 2 of 760 and 850 nm for conventional monitoring of O2Hb and HHb). The system has 8 continuous-wave measurement channels and monitors at 2 different vertical levels to detect variation in bladder fullness; IOD’s of 30 and 40mm provide information at 2 depths. Associations between optical densities during bladder emptying and then during natural filling were compared. Results: Data from 4 male and one female subject were analyzed. The optical densities recorded at the lower vertical locations showed positive correlation with the voiding rate (ratio of scale signal), and O2Hb and HHb concentration changes at higher vertical locations revealed muscle activation prior to voiding. Discussion: This pilot study provides proof of the feasibility of using a 950nm wavelength incorporated into a wearable NIRS bladder monitoring system to transcutaneously and non-invasively detect changes in bladder volume in real-time. Conclusions: Ongoing research is warranted to further evaluate the system as the bladder fills naturally; and establish the clinical value of the data obtained to patients living with spinal cord injury
Background: Spinal cord injury (SCI) compromises muscle function; when the pelvic floor muscles (PFM) are involved continence is affected. Women with partial injury rely on PFM rehabilitation therapy (PFMT) to aid continence, but the current lack of absolute measures to quantify training effects by monitoring changes in muscle oxygenation and perfusion hampers rehabilitation. We report clinical translation of a near infrared spectroscopic (NIRS) system to enable women with partial SCI to apply transvaginal optical detection of physiologic changes during PMFT as a point of care tool to quantify the effects of their PFM rehabilitation. Methods: The NIRS interface incorporates a circumferential grid of 6 LED emitters and 4 photodiode receivers with interoptode distances of 20 and 35 mm. The system was developed iteratively by engineers working with clinicians and patient care advocates to be clinically applicable for women following spinal cord injury. The continuous wave system uses 2-wavelengths (nominal 760nm, 850nm) and a sampling rate of 50Hz. Placed in the vagina during PMFT, the system monitors changes in oxy and deoxy-hemoglobin concentration (O2Hb/HHb) in real time at multiple points in the PFM. The slope of reoxygenation recovery post contraction is a measure of muscle oxidative capacity. Results: A point of care system was successfully developed that provides a means of detecting chromophore change occurring in the PFM during muscular contraction. The chromophore changes monitored also allow an absolute measure, HbDiff half-recovery time (½RT) to be derived. Comparison of these data over time provides a means of evaluating PMFT regimens for a training effect. In preparation for application in subjects with SCI, the reproducibility of SMVCs was monitored successfully in a pilot study where a volunteer conducted a series of 4 SMVCs on 15 occasions. Discussion: Skeletal muscle recovery from exercise-induced oxygen deficit indicates oxidative capacity; this equates with muscular fitness. SMVC is a robust measure of muscle strength and endurance, and HbDiff in occlusion free ½RT analysis reflects metabolic changes within muscle better than O2Hb. This clinical translation of NIRS provides a hand held system for women to use to quantify physiologic changes in their PFM; this will aid women with partial spinal cord injury in whom PFM function may either be too weak to be detected by physical exam or manometry, and may only be present unilaterally. Hence the merit of an optical system able to provide quantifiable measures of reoxygenation recovery as a measure of PFM fitness. A quantitative physiologic measure for evaluating for PMFT training effect is currently lacking Conclusions: The collaborative development of this self-contained transvaginal NIRS system, and prior proof that optical detection of a validated quantifiable oxygenation parameter is feasible in the pelvic floor, now allows clinical evaluation using this point of care system to aid women with partial spinal cord injury. The aim is to enable them to use this system to optimize their PFM rehabilitation therapy as means of enhancing their continence and quality of life.
Functional near infrared spectroscopy (fNIRS) is used for brain hemodynamic assessment. Cortical hemodynamics are reliably estimated when the recorded signal has a sufficient quality. This is acquired when fNIRS optodes have proper scalp coupling. A lack of proper scalp coupling causes false positives and false negatives. Therefore, developing an objective algorithm for determining fNIRS signal quality is of great importance. In this study, we developed a machine learning-based algorithm for quantitatively rating fNIRS signal quality. Our promising results confirm the efficacy of the algorithm in determining fNIRS signal quality and hence decreasing misinterpretations.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.