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Validation of an Acoustic Gastrointestinal Surveillance Biosensor for Postoperative Ileus



Postoperative ileus (POI) can worsen outcomes, increase cost, and prolong hospitalization. An objective marker could help identify POI patients who should not be prematurely fed. We developed a disposable, non-invasive acoustic gastro-intestinal surveillance (AGIS) biosensor. We tested whether AGIS can distinguish healthy controls from patients recovering from abdominal surgery.

Study Design

AGIS is a disposable plastic device embedded with a microphone that adheres to the abdominal wall and connects to a computer that measures acoustic event rates. We compared intestinal rates of healthy subjects using AGIS for 60 min after a standardized meal to recordings of two postoperative groups: (1) patients tolerating standardized feeding and (2) POI patients. We compared intestinal rates among groups using ANOVA and t tests.


There were 8 healthy controls, 7 patients tolerating feeding, and 25 with POI; mean intestinal rates were 0.14, 0.03, and 0.016 events per second, respectively (ANOVA p < 0.001). AGIS separated patients from controls with 100 % sensitivity and 97 % specificity. Among patients, rates were higher in fed versus POI subjects (p = 0.017).


Non-invasive, abdominal acoustic monitoring distinguishes POI from non-POI subjects. Future research will test whether AGIS can identify patients at risk for development of POI and assist with postoperative feeding decisions.

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Conflict of Interest

This study was conducted with funding from the Principal Investigators (B.S. and W.K.). The technology described in this study was developed by B.S. and W.K. and is managed by the UCLA Office of Intellectual Property (OIP). At the time of this study, UCLA submitted a patent application and was evaluating university in-licensing options. The authors did not receive outside funding to conduct this study. The opinions and assertions contained herein are the sole views of the authors and are not to be construed as official or as reflecting the views of the Department of Veteran Affairs.

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Correspondence to Brennan M. R. Spiegel or William Kaiser.

Additional information

This study was presented as an abstract at the 2014 Digestive Disease Week (DDW) in Chicago, Illinois.

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Spiegel, B.M.R., Kaneshiro, M., Russell, M.M. et al. Validation of an Acoustic Gastrointestinal Surveillance Biosensor for Postoperative Ileus. J Gastrointest Surg 18, 1795–1803 (2014).

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