Mesenteric perfusion at rest and during feeding in healthy children

In critical illness, mesenteric organs are at risk for ischemic injury. Near infrared spectroscopy (NIRS) measures an index of regional venous-weighted tissue oxyhemoglobin saturation, an approximation of regional oxygen supply-demand economy. Mesenteric NIRS measures have been utilized in critically ill neonates to monitor for necrotizing enterocolitis but have not been well-described in healthy infants or children. The purpose of this study was to provide preliminary estimates of normal values for mesenteric regional saturations in healthy infants and young children during activities including feeding.

We enrolled healthy infants and children between 1 month and 6 years for this observational study. Regional oxygen saturation (rSO₂) measures were obtained from cerebral, renal, and bilateral mesenteric-abdominal regions before, during, and after consuming a meal. Activity over the period of observation was categorized as calm, asleep, eating, post-prandial, active, and anxious states. We analyzed the association between physiologic parameters and clinical state using multilevel models.

Nineteen subjects (age 33.8 ± 20.7 months, weight 13.5 ± 4.7 kg [mean ± SD]) completed the study. Absolute rSO₂ measures varied between subjects, with state-dependent changes within subjects that were consistent between subjects. Cerebral rSO₂ varied little across states. Both mesenteric and renal rSO₂ varied across states with similar absolute values and trends across 5 of 6 clinical states, differing only in the asleep state, in which only renal rSO₂ increased. Small decreases in renal (-1.5%, SE 0.7, p < 0.01) and mesenteric (-1.7%, SE 0.7, p < 0.05) rSO₂ were observed with eating. Larger decreases were observed with anxiety for both renal (-7.7%, SE 1.0, p < 0.001) and mesenteric (-10.3, SE 1.4, p < 0.001) rSO₂.

In this study of healthy infants and young children, we observed small reductions in mesenteric rSO₂ in the post-prandial state. In contrast to cerebral rSO₂, both renal and mesenteric rSO₂ were significantly influenced by state, particularly activity and anxiety. The state-dependence of regional oxygen economy should be considered when interpreting renal and mesenteric rSO₂ measures.