Postprandial decline in abdominal regional oxygen saturation is associated with feeding intolerance in preterm infants: a prospective cohort study.

BACKGROUND: Feeding intolerance (FI) is a common morbidity in preterm infants, often preceding necrotizing enterocolitis (NEC). Near-infrared spectroscopy (NIRS) monitoring of abdominal regional oxygen saturation (A-rSO2) may detect impaired intestinal hemodynamics before clinical symptoms appear. OBJECTIVE: To investigate the relationship between A-rSO2 patterns and feeding tolerance in preterm infants. METHODS: A prospective observational cohort study of 30 preterm infants <37 weeks of gestation admitted at Dongguan Children's Hospital Affiliated to Guangdong Medical University between December 2020 to September 2021. A-rSO2 was measured pre-prandially (mean over a 10 min stable period) and post-prandially (mean commencing 30 min after feeding). Infants were stratified into FI (n = 7) and feeding tolerance (n = 23) groups based on clinical criteria. Univariate and multivariate logistic regression analyses were performed to identify factors associated with FI. Given the small sample size, the regression analysis is exploratory. RESULTS: The incidence of FI was 23.3%, and NEC was 10%. Infants with FI had significantly lower gestational age (32.1 vs. 35.2 weeks, p = 0.003) and lower birth weight (1.76 vs. 2.43 kg, p = 0.008). Multivariate analysis identified lower gestational age [adjusted OR (aOR): 0.505, 95% CI: 0.286-0.891] and a postprandial decline in A-rSO₂ (aOR: 13.03, 95% CI: 1.352-125.6) as independent factors associated with FI. Conversely, preterm formula feeding was associated with a significantly reduced odds of FI (aOR: 0.055, 95% CI: 0.004-0.762). The exploratory model demonstrated good discrimination (AUC=0.867, 95% CI: 0.763-0.964) and adequate calibration (Hosmer-Lemeshow p = 0.612). At the optimal cutoff probability of 0.384, sensitivity was 85.7% and specificity 82.6%. Internal bootstrap validation confirmed model robustness (optimism-corrected C-statistic = 0.867). Infants with NEC (n = 3) demonstrated significantly lower preprandial oxygenation and a greater postprandial change in oxygenation index. CONCLUSION: A postprandial decline in A-rSO2 may be a potential factor associated with feeding intolerance in preterm infants. NIRS monitoring of intestinal oxygenation provides a physiological indicator that warrants further investigation as a factor associated with gut dysfunction. These findings are hypothesis-generating and require validation in larger cohorts.