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Title: Low abdominal NIRS values and elevated plasma intestinal fatty acid-binding protein in a premature piglet model of necrotizing enterocolitis

Author
item ZAMORA, IRVING - Baylor College Of Medicine
item STOLL, BARBARA - Children'S Nutrition Research Center (CNRC)
item ETHUN, CECILIA - Baylor College Of Medicine
item SHEIKH, FARIHA - Baylor College Of Medicine
item YU, LING - Baylor College Of Medicine
item Burrin, Douglas - Doug
item BRANDT, MARY - Baylor College Of Medicine
item OLUTOYE, OLUYINKA - Baylor College Of Medicine

Submitted to: PLOS ONE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/23/2015
Publication Date: 6/10/2015
Citation: Zamora, I.J., Stoll, B., Ethun, C.G., Sheikh, F., Yu, L., Burrin, D.G., Brandt, M.L., Olutoye, O.O. 2015. Low abdominal NIRS values and elevated plasma intestinal fatty acid-binding protein in a premature piglet model of necrotizing enterocolitis. PLoS One. 10(6):e0125437. doi:10.1371/journal.pone.0125437.

Interpretive Summary: Necrotizing enterocolitis (NEC) is a serious and devastating disease that is the most common gastrointestinal emergency affecting 10% of premature, neonatal infants. Normal intestinal blood flow is poorly developed in premature infants and this has been linked to NEC. We previously demonstrated that near-infrared spectroscopy (NIRS) can be used as a feasible non-invasive method of measuring local tissue oxygen (StO[2]) content in pigs. The aim of this study was to establish whether comprehensive monitoring of StO[2] on the abdomen or belly along with other vital signs can be used to predict NEC in premature piglets. We demonstrated that continuously low abdominal StO[2] values and increased variability during initial feeds are highly predictive of NEC in premature piglets. We also showed that the concentration of a blood protein, called intestinal fatty acid binding protein, increases when NEC begins to develop and may also be a good marker to diagnose the disease. The study provides evidence that NIRS is a real-time, non-invasive tool that can be used to predict NEC.

Technical Abstract: To identify early markers of necrotizing enterocolitis (NEC), we hypothesized that continuous abdominal near-infrared spectroscopy (A-NIRS) measurement of splanchnic tissue oxygen saturation and intermittent plasma intestinal fatty-acid binding protein (pI-FABP) measured every 6 hours can detect NEC prior to onset of clinical symptoms. Premature piglets received parenteral nutrition for 48-hours after delivery, followed by enteral feeds every three hours until death or euthanasia at 96-hours. Continuous A-NIRS, systemic oxygen saturation (SpO[2]), and heart rate were measured while monitoring for clinical signs of NEC. Blood samples obtained at 6-hour intervals were used to determine pI-FABP levels by ELISA. Piglets were classified as fulminant-NEC (f-NEC), non-fulminant-NEC (nf-NEC) and No-NEC according to severity of clinical and histologic features. Of 38 piglets, 37% (n=14) developed nf-NEC, 18% (n=7) developed f-NEC and 45% (n=17) had No-NEC. There were significant differences in baseline heart rate (p=0.008), SpO[2] (p<0.001) and A-NIRS (p<0.001) among the three groups. A-NIRS values of NEC piglets remained lower throughout the study with mean for f-NEC of 69 +/- 3.8%, 71.9 +/- 4.04% for nf-NEC, and 78.4 +/- 1.8% for No-NEC piglets (p<0.001). A-NIRS <75% predicted NEC with 97% sensitivity and 97% specificity. NEC piglets demonstrated greater variability from baseline in A-NIRS than healthy piglets (10.1% vs. 6.3%; p=0.04). Mean pI-FABP levels were higher in animals that developed NEC compared to No-NEC piglets (0.66 vs. 0.09 ng/mL;p<0.001). In f-NEC piglets, pI-FABP increased precipitously after feeds (0.04 to 1.87 ng/mL;p<0.001). pI-FABP levels increased in parallel with disease progression and a value >0.25ng/mL identified animals with NEC (68% sensitivity and 90% specificity). NIRS is a real-time, non-invasive tool that can serve as a diagnostic modality for NEC. In premature piglets, low A-NIRS in the early neonatal period and increased variability during initial feeds are highly predictive of NEC, which is then confirmed by rising plasma I-FABP levels. These modalities may help identify neonates with NEC prior to clinical manifestations of disease.