Quantification and Modeling of Bladder Biomechanics Mechanisms Linking Spontaneous Rhythmic Contractions and Dynamic Elasticity to Detrusor Overactivity

Overactive bladder (OAB) is a chronic condition affecting approximately 20% of adults in the United States. Detrusor overactivity (DO) is the presence of non-voiding contractions in the detrusor (bladder) muscle during filling and is present in some individuals with OAB. DO is currently identified visually during a urodynamics (UD) study involving pressure catheters and filling and voiding of the bladder to evaluate function. UD provides limited subtyping of DO, and an incomplete understanding of mechanisms contributing to OAB. Aim 1 of this study was to develop objective tools to quantify, subgroup and better understand rhythmic DO. The results indicate that high amplitude rhythmic DO may represent a clinically significant OAB subtype. Aim 2 focused on a biomechanical bladder property, dynamic elasticity (DE), identified during a previous pilot study. DE may contribute to regulation of bladder wall tension and was characterized in a pig bladder model and participants with and without OAB. A conceptual model linking DO and dynamic elasticity was tested. Novel tools to detect and quantify DO in a more objective fashion were developed and provided evidence that high amplitude rhythmic DO may be clinically significant. DE was characterized clinically and in an isolated pig bladder model. A novel DE index was defined. Testing the conceptual model identified an association between dynamic elasticity and the absence of DO. Quantifying DO and characterizing dynamic elasticity provided important insight the regulation of bladder wall biomechanics and how this regulation may be altered by DO in individuals with OAB

Optimization of an Automated Algorithm for Analysis of Spontaneous Rhythmic Bladder Contractions During Urodynamics Testing

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Emergency Glucagon Injection Device

Glucagon is a drug administered to people with diabetes that are experiencing a seizure due to low blood glucose levels. The current method of injecting glucagon during a hypoglycemic seizure is lengthy and complicated when time equates to minimizing the effects of an emergency situation. This project is student created and the result of the design team recognizing a serious problem and deciding to find a better solution. The goal of this project was to streamline this process. Several working prototypes were developed and evaluated before a final design was chosen. Safety, durability and usability were all considerable factors. The properties of glucagon require it to be stored in a powered form until before it is injected. Therefore, the device had to safely store the medicine and diluting solution separately. It is also important that the injection device is robust enough to be carried around by the person with diabetes to have it in case of emergency. The novel part of this design was how the two components were separated via a barrier and once that was removed and the two drugs mixed the injection device sealed itself. The approach taken with this development was an iterative version of the design process. Several concepts were brainstormed and from that a practical solution was developed. The final 3-D printed prototype meets and exceeds the goal by reducing the preparation time to one-eighth of the previous kit. This device has the potential to save lives and provide sense of safety to people with diabetes.https://scholarscompass.vcu.edu/capstone/1134/thumbnail.jp

Automated quantification of low amplitude rhythmic contractions (LARC) during real-world urodynamics identifies a potential detrusor overactivity subgroup.

OBJECTIVES:Detrusor overactivity (DO) is characterized by non-voiding detrusor smooth muscle contractions during the bladder filling phase and often contributes to overactive bladder. In some patients DO is observed as isolated or sporadic contractions, while in others DO is manifested as low amplitude rhythmic contractions (LARC). The aim of this study was to develop an objective method to quantify LARC frequencies and amplitudes in urodynamic studies (UDS) and identify a subgroup DO of patients with LARC. METHODS:An automated Fast Fourier Transform (FFT) algorithm was developed to analyze a 205-second region of interest of retrospectively collected "real-world" UDS ending 30 seconds before voiding. The algorithm was designed to identify the three largest rhythmic amplitude peaks in vesical pressure (Pves) in the 1.75-6 cycle/minute frequency range. These peak Pves amplitudes were analyzed to determine whether they were 1) significant (above baseline Pves activity) and 2) independent (distinct from any in abdominal pressure (Pabd) rhythm). RESULTS:95 UDS met criteria for inclusion and were analyzed with the FFT algorithm. During a blinded visual analysis, a neurourologist/urodynamicist identified 52/95 (55%) patients as having DO. The FFT algorithm identified significant and independent (S&I) LARC in 14/52 (27%) patients with DO and 0/43 patients (0%) without DO, resulting in 100% specificity and a significant association (Fischer's exact test, p<0.0001). The average slowest S&I LARC frequency in this DO subgroup was 3.20±0.34 cycles/min with an amplitude of 8.40±1.30 cm-H2O. This algorithm can analyze individual UDS in under 5 seconds, allowing real-time interpretation. CONCLUSIONS:An FFT algorithm can be applied to "real-world" UDS to automatically characterize the frequency and amplitude of underlying LARC. This algorithm identified a potential subgroup of DO patients with LARC