This research targets the development of improved therapy for gastroparesis, a relatively rare disease mostly affecting Type I diabetic patients that can induce strong feelings of isolation and depression without effective treatment.

Gastroparesis is a condition in which food cannot be properly passed from the stomach to the small intestine. It is commonly observed in Type I diabetic patients as a result of vagal neuropathy, surgery, infection in the gastrointestinal (GI) tract, or from an unknown cause. In a study analyzing the National Inpatient Sample Database (NIS), a principal discharge diagnosis of gastroparesis increased from 3,978 admissions in 1997 to 17,220 admissions in 2012[1]. However, the overall prevalence of gastroparesis is difficult to estimate, with various studies ranging from 18% to 48% of diabetic individuals presenting with symptoms [2]. In an in-depth study of 9 patients living with gastroparesis, it was discovered that feelings of loss, isolation, and rejection were associated with being around food and mealtime, emphasizing the disease?s effect on daily life [3]. If drug treatments or dietary changes are ineffective, patients may receive a gastric electrical stimulator, which is an implantable pacemaker-like device that electrically stimulates the antrum of the stomach to help relieve persistent nausea and vomiting. However, there is little knowledge of how this device works with disease mechanisms and how symptoms manifest. Because of this, it can be difficult to optimize the settings for each patient, causing many to continue to suffer from symptoms including extreme nausea and vomiting.

The Center for Implantable Devices, in conjunction with the Gastrointestinal Motility Center at the Indiana University School of Medicine in Indianapolis, IN, is developing new stimulators that could rapidly individualize device settings based on bioelectric signals measured from their vagal nerves. These vagal signals can be measured from the skin surface, preventing the need for additional implants to receive benefits from the technology. Through clinical studies, it was discovered that patients with gastroparesis who are considered ?responders? to gastric electrical stimulation have a specific signal that travels through their vagal nerves when the stimulator is turned on. The algorithm-enhanced stimulators under development may one day help more patients with gastroparesis find relief from constant nausea and vomiting by guiding the physician to device settings that produce the vagal signals associated with positive treatment outcomes.

In the figure above, part A demonstrates cutaneous recordings collected with an 8-channel PowerLab system (AD Instruments) with EKG pad electrodes that are positioned along the length of the left and right cervical vagus nerve. Part B of the figure shows the Bionode, a state-of-the-art implantable neurostimulator developed by the Center for Implantable Devices at Purdue University, featuring 1 channel for stimulation, 2 channels for recording, wireless programmability and wireless powering. Part C of the figure displays the Bionode during production.

• Project Researcher: Matt Ward