title: Protein Kinetics and Metabolic Effects Related to Disease States in the Intensive Care Unit.
abstract: Evaluating protein kinetics in the critically ill population remains a very difficult task. Heterogeneity in the intensive care unit (ICU) population and wide spectrum of disease processes creates complexity in assessing protein kinetics. Traditionally, protein has been delivered in the context of total energy. Focus on energy delivery has recently come into question, as the importance of supplemental protein in patient outcomes has been shown in several recent trials. The ICU patient is prone to catabolism, immobilization, and impaired immunity, which is a perfect storm for massive loss of lean body tissue with a unidirectional flow of amino acids from muscle to immune tissue for immunoglobulin production, as well as liver for gluconeogenesis and acute phase protein synthesis. The understanding of protein metabolism in the ICU has been recently expanded with the discovery of how the mammalian target of rapamycin complex 1 is regulated. The concept of "anabolic resistance" and identifying the quantity of protein required to overcome this resistance is gaining support among critical care nutrition circles. It appears that a minimum of at least 1.2 g/kg/d with levels up to 2.0 g/kg/d of protein or amino acids appears safe for delivery in the ICU setting and may yield a better clinical outcome.
authors.affiliation: 1 Department of Surgery, Oregon Health & Science University, Portland, Oregon, USA.
authors.forename: Robert G
authors.initials: RG
authors.lastname: Martindale
authors.affiliation: 2 Clinical Evaluation Research Unit, Kingston General Hospital, Kingston, Ontario, Canada.|3 Department of Medicine, Queen's University, Kingston, Ontario, Canada.
authors.forename: Daren K
authors.initials: DK
authors.lastname: Heyland
authors.affiliation: 4 Surgery Department, Pontificia Universidad Javeriana, Medical School, Hospital Universitario San Ignacio, Bogota, Colombia.
authors.forename: Saúl J
authors.initials: SJ
authors.lastname: Rugeles
authors.affiliation: 5 Department of Anesthesiology and Intensive Care Medicine, Karolinska University Hospital, Huddinge, Sweden.
authors.forename: Jan
authors.initials: J
authors.lastname: Wernerman
authors.affiliation: 6 Department of Intensive Care Medicine, Department of Internal Medicine, VU University Medical Center Amsterdam, Amsterdam, the Netherlands.|7 Faculty of Sports and Nutrition, Amsterdam University of Applied Sciences, Amsterdam, the Netherlands.
authors.forename: Peter J M
authors.initials: PJ
authors.lastname: Weijs
authors.affiliation: 8 Division of Pulmonary & Critical Care Medicine, Department of Medicine, Medical College of Wisconsin, Milwaukee, Wisconsin, USA.
authors.forename: Jayshil J
authors.initials: JJ
authors.lastname: Patel
authors.affiliation: 9 Department of Medicine, University of Louisville, Louisville, Kentucky, USA.
authors.forename: Stephen A
authors.initials: SA
authors.lastname: McClave
mesh_terms: D000596:Amino Acids / Q000378:metabolism; D016638:Critical Illness; D004044:Dietary Proteins / Q000378:metabolism*; D004734:Energy Metabolism; D006801:Humans; D007362:Intensive Care Units; D010288:Parenteral Nutrition
chemical_list: D000596:Amino Acids; D004044:Dietary Proteins
keywords: amino acids; anabolic resistance; critical illness; intensive care unit; metabolism; proteins; rapamycin complex 1