Validation of an acoustic gastrointestinal surveillance biosensor for postoperative ileus.

BACKGROUND: 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. RESULTS: 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). CONCLUSION: 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.