Post-treatment dopexamine infusions partially reverse reductions in cranial mesenteric blood flow and mucosal oxygenation induced by hypoxia in newborn piglets

A severe hypoxic insult is known to induce dramatic reductions in newborn i ntestinal blood flow and is, thus, considered a vector for the development of neonatal intestinal ischemic diseases. Dopexamine (DPX) is a novel synth etic agent that has potent B-2-adrenoceptor and dopaminergic activity, the clinical effects of which include an increase in cardiac output and in mese nteric blood now. Having previously shown that infusion of DPX before hypox ia (HYP) mitigated the reduction in newborn mesenteric blood flow, we sough t to define its efficacy when given after an established hypoxic insult. Ul trasonic transit time blood flow probes were placed around the ascending ao rta and cranial mesenteric artery of anesthetized, mechanically ventilated 0 to 2-day-old piglets. Small bowel mucosal oxygenation was observed with a tissue oxygen monitoring system. After stabilization, animals were subject ed to one of the following: HYP (FIO2 = 0.12) for 60 minutes (n = 12); DPX (5 mu g/kg/min) infusion begun 10 minutes after induction of HYP/DPX (n = 1 1). Almost no alterations in any of the monitored variables were shown in a group (n = 5) of similarly instrumented, untreated animals. In contrast, a lthough both hypoxic piglet groups experienced significant (P < 0.05, analy sis of variance) declines from baseline cardiac output, mesenteric blood fl ow, and mucosal oxygenation, each of these deleterious effects was signific antly (P < 0.05) blunted in the DPX-treated animals. During periods of syst emic hypoxemia, the reductions in neonatal mesenteric blood flow and oxygen ation can be somewhat blunted by DPX. As such, this agent may prove of clin ical benefit when an infant is threatened by a hypoxic episode.