A tetrapolar bio-impedance sensing system for gastrointestinal tract monitoring

Surgical Site Infection (SSI) imposes a significant burden clinically and compromises patient recovery. Anastomosis in the gastrointestinal (GI) tract is a particularly challenging case where failure of the anastomosis can lead to leakage, resulting in an increase in mortality rates. However early diagnosis and intervention are hampered by a lack of continuous sensing and long diagnostic intervals of current clinical practices. Tissue ischemia in the vicinity of the anastomosis has been found to be an early surrogate marker for anastomotic leakage. Electrical bio-impedance is a promising non-invasive technique for identifying and monitoring tissue ischemia. In this paper the modelling, design and validation of a bio-impedance system including compact instrumentation and a novel bio-impedance sensor optimized for mucosal tissue measurements in the GI tract are presented. The preliminary system, including the impedance probe, is validated experimentally for GI implant applications to provide early detection of tissue ischemia following GI surgery.