Continuous duodenal feeding restores gut blood flow and increases gut oxygen utilization during PEEP ventilation for...

Positive end-expiratory pressure (PEEP) improves oxygenation but, at moderate levels, limits portal blood flow (PBF) and may cause relative splanchnic ischemia. Under these conditions, methods of supporting gut physiology may prevent the sequelae of gut ischemic damage. Enteral feeding is known to cause splanchnic hyperemia in uninjured animals. In order to study the effects of continuous enteral feeding on gut hemodynamics in a flow-limited environment, six dogs underwent the insertion of arterial, pulmonary artery, and portal and hepatic vein catheters. Splenectomy and duodenostomy were performed, and the hepatic artery and portal vein were encircled with flow probes. Lung injury (LI) was undertaken with intravenous oleic acid (0.08 mL/kg), followed by incremental additions of PEEP totaling 10 cm H2O to correct shunt. Continuous elemental feeding (1 kcal/mL, 3 mL/kg/hr) was started through the duodenostomy. Cardiac index (CI), PBF, and gut oxygen delivery and consumption (GO2D, GO2C) were measured at baseline (T0), 1 hour after LI and PEEP (T1), and 1 hour after drip feeding was begun (T2). Lung injury and PEEP significantly decreased CI, PBF, and GO2D without changing GO2C. Feeding returned PBF and GO2D to baseline levels without changing CI. GO2C increased significantly compared with baseline levels. Based on prior studies, these changes do not represent recovery of the injured model. Continuous enteral feeding, therefore, redistributed CI to the portal circulation. The improved gut hemodynamics documented in this model may preserve splanchnic integrity and prevent gut-derived complications.