Splanchnic blood flow, oxygen delivery and oxygen consumption in hypotensive newborn piglets

To investigate the relationship between splanchnic visceral oxygen supply and consumption, we altered O2 delivery by decreasing gastrointestinal blood flow during hypotension, and examined the effect on splanchnic oxygen consumption and extraction. We used 10 anesthetized newborn piglets, and measured blood flow using radioactive microspheres. Blood flow fell as perfusion pressure fell in all splanchnic organs, the correlation being most marked in the small intestine. Oxygen consumption was linearly related to blood pressure, and despite a rise in splanchnic oxygen extraction with low blood pressure, splanchnic oxygen consumption was highly dependent on oxygen delivery when oxygen delivery was below a critical value of 0.17 +/- 0.05 mmol/100 g/min. We conclude that the newborn piglet gut is incapable of maintaining a constant oxygen supply during the low-flow state produced by hypotension.