title: Stable isotopic quantitation of protein metabolism and energy expenditure in neonates on- and post-extracorporeal life support.
abstract: It is generally assumed that extracorporeal life support (ECLS) provides a metabolic "rest state" by replacing approximately 80% of cardiopulmonary work. The aim of this study was to precisely quantify neonatal energy expenditure (EE) and whole-body protein metabolism on (during) and post (after) venoarterial ECLS using stable isotope tracer techniques. Nine parenterally fed neonates on-ECLS were studied at 7.8 +/- 1.0 days of life (mean +/- SE), five of which were studied post-ECLS on 27.0 +/- 5.4 days of life. EE and whole-body protein metabolism were quantified using a primed, continuous infusion of L-[1-(13)C]leucine and NaH13CO3. The neonates studied on- and post-ECLS had similar rates of endogenous leucine flux (370 +/- 46 micromol/kg/h v 339 +/- 76 micromol/kg/h), leucine oxidation (161 +/- 22 micromol/kg/h v 121 +/- 25 micromol/kg/h), nonoxidative disposal rates of leucine (313 +/- 37 micromol/kg/h v 331 +/- 75 micromol/kg/h), net protein balance (-2.31 +/- 0.8 g/kg/d v -0.33 +/- 1.1 g/kg/d), and EE (88.6 +/- 7.7 kcal/kg/d v 84.3 +/- 9.2 kcal/kg/d). These results demonstrate that neonates on-ECLS are in hypermetabolic and protein catabolic states that continue in the post-ECLS phase. The authors conclude that ECLS does not provide a metabolic "rest state."
authors.affiliation: Department of Surgery, Baylor College of Medicine and Texas Children's Hospital, Houston 77030-2399, USA.
authors.forename: T H
authors.initials: TH
authors.lastname: Keshen
authors.forename: R G
authors.initials: RG
authors.lastname: Miller
authors.forename: F
authors.initials: F
authors.lastname: Jahoor
authors.forename: T
authors.initials: T
authors.lastname: Jaksic
mesh_terms: D002245:Carbon Dioxide / Q000097:blood; D004734:Energy Metabolism; D015199:Extracorporeal Membrane Oxygenation; D006801:Humans; D007231:Infant, Newborn; D007553:Isotope Labeling; D007930:Leucine / Q000097:blood; D010084:Oxidation-Reduction; D010289:Parenteral Nutrition, Total; D011506:Proteins / Q000378:metabolism*
chemical_list: D011506:Proteins; D002245:Carbon Dioxide; D007930:Leucine