A novel pump to improve bladder emptying and irrigation in patients who use clean intermittent catheterization
Arjun Rajan, BSE1, Likitha Nimmagadda, BSE1, Emily R. Bozich, BSE1, Jason W. Lo, BSE1, Jason Qu, BSE1, Julian Wan, MD2, Bryan S. Sack, MD2.
1Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, USA, 2Department of Urology, University of Michigan, Ann Arbor, MI, USA.
BACKGROUND: Neurogenic bladder patients who intermittently catheterize may have systems that drain slowly and incompletely. This can promote UTIs, formation of bladder stones and be time consuming. We hypothesize that a catheter accessory device could improve drainage, reduce residual bladder volume, and save time. METHODS: A year-long collaboration between a Biomedical Engineering Capstone design team and client mentors from the affiliated medical school pediatric urology department led to a thorough evaluation of solutions to enhance emptying of bladders that require intermittent catheterization. The students performed market analysis, identified design requirements, generated design concepts, conducted usability testing, and constructed alpha and beta prototypes verified through benchtop experimentation. Prototypes were verified through use of a phantom bladder model built from a compliant stress ball with an attached catheter and placed under an external pressure of 5 cm H2O. Tests were conducted to measure the difference between passive drainage and device-based drainage at various bladder volumes (150 mL, 300 mL, and 600 mL) and catheter sizes (10, 12, 14 FR). Eight student peers compared passive emptying, irrigating, and aspirating a phantom bladder model using the prototype or using a syringe to assess the usability of the device. RESULTS: Through the engineering process, a portable catheter pump (PCP) to interface with current intermittent catheters was developed. The PCP housing (Figure 1) was designed in SolidWorks design software and 3D printed. Fluid can be moved bidirectionally using a battery powered peristaltic pump and microcontroller. The PCP has a built-in load sensor with an automatic shut-off safety mechanism. Testing results showed that for all bladder fill volumes and catheter sizes, the PCP emptied >98% of fluid in the bladder and drained between 1.6 and 6.3 times faster when compared to passive drainage (Figure 2). Initial usability feedback from 8 participants showed that the PCP required less physical effort to irrigate the bladder when compared to manual syringe technique. CONCLUSIONS: This portable catheter pump prototype improves phantom bladder emptying by increasing flow rate, decreasing residual volume, and making irrigation easier. Future design improvements will work to implement safety mechanisms and miniaturize the PCP. This project demonstrates both the feasibility of a catheter accessory device to improve patient quality of life and the ability for understudied clinical problems to be addressed through collaborations between capstone engineering design teams and physicians. 
Figure 1. PCP Design Interface [Created with BioRender.com].
Figure 2. Representative results for PCP vs. Passive Drainage: Left: Remaining volume after drainage using a 12 FR catheter. Right: Average emptying rate for bladders initially filled with 600mL. *** indicates p<0.001
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