Effects of hypoxemia on gastrointestinal blood flow and gastric emptying in the newborn piglet.

The effects of severe hypoxemia on gastrointestinal (GI) blood flow and gastric emptying were studied in nine 2- to 4-day-old piglets which were mechanically ventilated while receiving nitrous oxide anesthesia. Each animal was studied during a control period of oxygenation (PaO2 91 +/- 8 torr), 35 min of hypoxemia (PaO2 29 +/- 1 torr), and a recovery period (PaO2 90 +/- 5 torr) (mean +/- SEM). During each study period, the animal received a 10% dextrose test meal with phenol red marker (22 ml/kg), gastric residual volumes were determined at 10-min intervals over 30-min study periods using a dye dilution double sampling technique, and GI blood flow (radionuclide-labeled microspheres), O2 delivery, O2 extraction, and O2 consumption were measured at the end of the 30-min period. Hypoxemia resulted in decreased blood flow to the following GI organs: stomach, jejunal and ileal mucosa-submucosa, and colon decreased 62, 31, and 35%, respectively (p less than 0.05). Jejunal and ileal muscularis blood flow remained unchanged. Oxygen delivery and consumption by GI tract decreased 79 and 58%, respectively; whereas oxygen extraction of GI tract increased 115%. Values returned toward baseline levels during the recovery period. The hypoxemic gastric emptying pattern showed significantly greater gastric residuals at 20 min compared to the 10-min value (p less than 0.05). This pattern was different than that observed during control and recovery periods. We conclude that severe hypoxemia results in decreased GI blood flow, tissue oxygenation, and an altered gastric emptying pattern. These observations may have clinical significance for feeding infants following an hypoxemic episode.