Effects of severe hypoxemia on mesenteric blood flow in neonatal piglets

Background. The purpose of this work was to determine the effects of hypoxe mia on systemic hemodynamic variables and regional conduit arterial blood h ows in neonatal piglets. Materials and methods. Using transit time blood how probes, cardiac output and cranial mesenteric artery blood flow were monitored in groups of premat urely delivered (90% of term gestational age) and a-week-old piglets prior to, during, and after exposure to a 30-min hypoxic (FIO2 = 0.12) challenge. Results. The documented alterations in systemic mean arterial pressure and cardiac output pressure during hypoxia and reoxygenation were consistent wi th the maturational age of the animals, In response to hypoxia, all animals demonstrated significant reductions in mesenteric blood how, with returns to baseline levels during the 30-min reoxygenation phase. In still other pr ematurely delivered piglets, nutrient mesenteric arterial blood flows were measured using in vivo videomicroscopy. The marked hypoxemia-induced declin e in mucosal blood flow was reversed by reoxygenation, Conclusions. The physiologic mechanisms responsible for neonatal mesenteric vasoactive responsiveness are present in conduit and in nutrient vessels w ell prior to birth and can be activated by a significant perturbation. Thes e observations are germane insofar as they provide a stable, age-matched ac ute animal model to study neonatal intestinal ischemic diseases, including necrotizing enterocolitis. (C) 1998 Academic Press.