GLUCOSE METABOLISM IN NEWBORN INFANTS WITH RESPIRATORY ILLNESS

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Sick neonates, especialy those with respiratory illness, usually require Total Parenteral Nutrition (TPN) during the course of their illness and until their ability to tolerate enteral feeds is well established. These infants, as well as those born prematurely, are at risk of a disturbed glucose metabolism and an inadequate energy supplementation. In an effort to prevent hypoglycemia and to provide a sufficient energy intake, some of these neonates are routinely receiving glucose infusion rates of twice their turn over rate (normal turnover rate: 6-8mg/kg/min.). When this is done, particularly in very premature infants, hyperglycemia becomes a more frequent complication. We do not know how changing the glucose infusion rate affects the glucose metabolism and the blood glucose levels in newborns with respiratory illnesses. The purpose of this project is to determine the effects of different glucose infusion rates on glucose, lipid, and protein metabolism in newborn infants with severe pulmonary diseases. It is important for us to learn about the physiology of glucose metabolism in these sick neonates for it will enable us to formulate an adequate parenteral nutrition that renders these infants normoglycemic as it also would provide them with a sufficient energy intake. HYPOTHESIS 1. Hyperglycemia is more likely to occur while on routine TPN (usually providing glucose at rates corresponding to twice the normal glucose turnover rate) than on a TPN with a 6 mg/kg/min. glucose infusion rate (normal glucose turnover rate). 2. Newborn infants with respiratory illness are able to maintain normoglycemia during a 6mg/kg/min glucose infusion rate (while maintaining the infusion rates of parenteral lipids and amino acids unchanged). 3. Glucose production, particularly gluconeogenesis, is not completely suppressed in infants with respiratory illness while receiving a routine TPN providing glucose at twice normal turnover rate. 4. Glycerol is a significant gluconeogenic substrate. 5. Whole-body protein breakdown and oxidation is not increased in sick infants receiving a TPN providing glucose at 6mg/kg/min SPECIFIC AIMS The purpose of this study is to determine the effects of routing TPN (providing glucose at about twice normal turnover rates), and of reducing the infusion rate of glucose to correspond to the normal glucose turnover (while maintaining the infusion rates of parenteral lipids and amino acids unchanged) on glucose, lipid and protein metabolism in infants with respiratory illness such as IRDS, meconium aspiration and pneumothorax using established Stable Isotope-GCMS techniques. This will allow us to determine the metabolic effects of glucose infusion rate in sick newborn infants with respiratory illness.