Hyperosmolal feedings and gastrointestinal blood flow and oxygenation in newborn lambs.
Hyperosmolal feedings have been implicated as a cause of potential disruption to the physiology of the neonatal intestinal tract. To evaluate this we studied eight awake lambs (11 +/- 2 days old) with chronically implanted catheters in the portal sinus, descending aorta, and left and right ventricles. Blood flow (Q) was calculated with the radionuclide-labeled microsphere technique and O2 delivery (DO2) and consumption (VO2) by the Fick principle using blood O2 contents. Lambs were studied initially after a 4-h fast and sequentially at 2, 3, and 4 h after eating a hyperosmolal (590 mOsmol) formula. Cardiac output (mean +/- SEM, 332 +/- 22 ml.min-1.kg-1) and whole animal VO2 (16.5 +/- 2.5 ml O2.min-1.kg-1) remained stable. Total gastrointestinal (GI) blood flow increased 28% by 3 h. Small intestine Q increased 21% 3 h after feeding and then returned to baseline. Similarly, large intestinal Q increased 77% after feeding and remained elevated. There was no effect on stomach Q. Total GI vascular resistance fell 28% 3 h after feeding then returned to baseline. DO2 to the GI tract increased at 3 h and returned to baseline. There was no change, though, in GI VO2 (3.9 +/- 0.4 ml O2.min-1.100 g-1) or in the extraction (VO2/DO2) of oxygen (21.2 +/- 1.8%) during the study. Furthermore, there was no evidence for GI tract acidosis at any time. Systemic organ blood flow (except hepatic arterial blood flow) remained unchanged.(ABSTRACT TRUNCATED AT 250 WORDS)
Department of Pediatrics, Magee-Women's Hospital, University of Pittsburgh, School of Medicine, PA 15213.
D E
DE
Buchanan
I R
IR
Holzman
D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D001775:Blood Circulation; D001783:Blood Flow Velocity; D001794:Blood Pressure; D002302:Cardiac Output; D002408:Catheters, Indwelling; D004064:Digestive System / Q000000981:diagnostic imaging; D004068:Digestive System Physiological Phenomena; D005766:Gastrointestinal Contents / Q000032:analysis; D006400:Hematocrit; D006940:Hyperemia / Q000503:physiopathology; D009994:Osmolar Concentration; D010101:Oxygen Consumption; D011877:Radionuclide Imaging; D012756:Sheep / Q000502:physiology*