Gastrointestinal blood flow and O2 uptake in piglets: recovery from hypoxemia

Gastrointestinal (GI) blood flow, O2 transport, and O2 uptake were measured during recovery from severe hypoxemia in newborn piglets. Hypoxemia was induced by lowering the inspired O2 concentration to 0.05 for 15 min. This resulted in an 82% decrease in GI O2 uptake. Recovery measurements were obtained 5 and 65 min after restoration of normoxia. During early recovery (5 min), GI O2 uptake increased above prehypoxemia baseline, presumably to "repay" the O2 deficit incurred during hypoxemia. This was mediated by an increase in the arteriovenous O2 content difference, as GI blood flow did not increase above prehypoxemia baseline. During late recovery (65 min), GI blood flow, O2 delivery, and arteriovenous O2 content difference decreased below prehypoxemia baseline. This resulted in a 52% decrease in GI O2 uptake below prehypoxemia baseline. Therefore, early recovery was characterized by an appropriate increase in GI O2 uptake; however, late recovery was characterized by a significant reduction in GI O2 transport and uptake. Circulatory homeostasis was not reestablished during the late recovery period.