STTR Phase I: Development of novel ultrasound-visible percutaneous dilation system

This broader impact/commercial potential of this STTR Phase I project is to address certain medical procedures, such as percutaneous nephrolithotomy (PCNL). Currently, one in 11 people develop kidney stones by the age of 70, with a lifetime recurrence rate of 60-80%. PCNL, which involves removal of kidney stones through a surgical channel into the kidney, is the preferred method for stones less than 2 cm. However, availability of this critical procedure is limited by technical difficulty and cost. Current dilation systems are (1) cumbersome, requiring two skilled users, (2) not optimized for ultrasound visibility, limiting use of this less expensive, radiation-free imaging modality, (3) damaging to the kidney, and (4) only allow pre-selected tract diameter, inhibiting miniaturized access adoption. The product developed in this proposal will reduce the time, cost, and negative side effects of PCNL by providing one-step dilation with combined dilator, balloon, and sheath; offering several operating diameters with the same sheath; and providing ultrasound visibility. This technology can help hospitals recoup up to 20% of direct costs per procedure by facilitating the transition to ultrasound-based dilation and more miniaturized access. The less invasive nature of this dilator can potentially avoid expensive complications and convert the requirement for a hospital stay into an out-patient procedure. The proposed STTR Phase I project will address achieving ultrasound visibility, as a device made of a thin polymer is typically hard to detect on ultrasound. To optimize the dilator for ultrasound visibility, the effects of parameters such as geometric changes, surface texture, material, echogenic coatings, and reagents on ultrasound visibility must be assessed, with a focus on delineating the tip of the sheath for maximal precision and safety. The material also needs to 1) maintain columnar stiffness for penetration into tissue, 2) resist radial compression when in the expanded and locked position, 3) be flexible and thin enough to roll tightly around a balloon dilator, 4) be lubricious to allow sliding expansion to occur smoothly and 5) be durable enough to withstand post processing and sterilization. This project will advance the development of a sheath and tip to be adapted for extrusion manufacturing and integrated with current balloon dilators. Verification and validation studies will be conducted to demonstrate the improvement in visibility, procedure speed and ease of use, and quantitative material testing will be conducted. Mechanical evaluation will include: radial compression, tensile strength, sheath fatigue from torque, durability, and performance following aging. Through this program, the product will demonstrate the theoretical and practical capabilities of using thin plastic devices for ultrasound guided procedures. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.