Research Project
9346234
Project Summary The clinical advantages of intraperitoneal (IP) insulin delivery have been established in multiple studies. These advantages include reduction in blood glucose swings, reduced frequency of hypoglycemia and ease of control. They are a result of rapid, first pass delivery of insulin to the liver, rapid clearance of plasma insulin, and normalization of the portal to peripheral insulin gradient. This effort addresses a key component of the long-term objective to develop a fully implanted platform comprising a small pump, stable concentrated insulin analog, a long-life intraperitoneal sensor, and closed-loop algorithm. This platform is important to public health in that is provides a cost-effective diabetes management tool to the wide diabetic population, which offers superior blood glucose control, and reduction in diabetes complications, costs, and overall health burden. An enabling and necessary component of an IP insulin delivery system is the ability to safely and efficiently maintain the implanted portions of the system, including insulin delivery catheters and glucose sensors. The overall aim of this effort is to develop a fully implanted catheter replacement port as a component of an implanted pump system. The replacement port will provide fluid connection to the intraperitoneal insulin delivery catheter and electrical connections to the glucose sensors, and enable a safe, brief procedure using only a small incision and trocar/cannula access to remove and replace the catheter and sensors. The effort comprises three specific aims. Specific Aim 1 includes the manufacture of prototypes and bench testing. Test parameters include reliable connection of the fluid path including absence of leakage or obstruction to fluid flow, resistance of the conductors, isolation between distinct conductors, isolation of conductors from the surrounding medium, and leakage currents. In SA2 we will verify that a replacement port in conjunction with an established catheter entry site through the rectus abdominis muscle is a practical fibrous tissue structure for removing and replacing a catheter. In three dogs, four mock catheter replacement ports each will be implanted on the anterior abdominal wall, with the associated catheter extending into the intraperitoneal space (12 total). One replacement port will include a catheter around which a track may be established, and two catheter replacement ports will include experimental catheter guide tubes which penetrate through the abdominal wall. The fourth replacement port will be placed just beneath the anterior rectus sheath in order to simulate a similar necessary placement in a thin human patient with minimal SQ fat. After 135 days implanted, the dogs will undergo removal of the mock catheter replacement ports, and replacement of these with new mechanically functional replacement ports. These will then have their associated catheters removed and replaced transcutaneously using a proprietary exchange catheter, to simulate the process in a human. Histologic examination will be performed on the explanted catheters and replacement ports. In SA3 we will verify the catheter replacement port implant procedure and the catheter replacement procedure for safety, simplicity, efficiency, and suitability for general surgical suitability using a small incision and trocar/cannula access. Using the three dogs from SA2, at the time of explant of the original four devices per dog, we will implant one replacement port and catheter in a new site in each dog. We seek to confirm that the procedure is minimally invasive, brief, and attractive to physicians as a simple procedure.
