title: A descriptive study of skeletal muscle metabolism in critically ill patients: free amino acids, energy-rich phosphates, protein, nucleic acids, fat, water, and electrolytes.
abstract: OBJECTIVE
  To characterize biochemical changes in skeletal muscle in critically ill patients.
  
  
  METHODS
  Survey of critically ill patients.
  
  
  METHODS
  Intensive care unit (ICU) at a university hospital.
  
  
  METHODS
  Critically ill patients (n = 20) subjected to trauma, surgical complications, and/or bacteremia who were treated in the ICU and showed no risk of bleeding complications were included. Reference groups of metabolically healthy volunteers and patients served as the control/reference groups.
  
  
  METHODS
  Percutaneous muscle biopsy was obtained from both patients and healthy volunteers.
  
  
  RESULTS
  Total free amino acids in skeletal muscle decreased 59% (p < .001) and skeletal muscle glutamine concentration decreased 72% (p < .001) in the critically ill patients. Basic amino acids decreased 49% (p < .001). Branch-chain amino acids increased 39% (p < .01), and aromatic amino acids increased 88% (p < .001) in the patients. Adenosine triphosphate (ATP) was reduced by 12% (p < .01). Total creatine concentration increased by 26% (p < .001) due to an 80% increase in free creatine (p < .001). The phosphorylated creatine fraction of total creatine decreased 22% (p < .001) in the patients. Alkali-soluble protein/DNA decreased 24% (p < .01) and fat free solid/DNA decreased 21% (P <.01) in patients sampled on or after ICU day 5 compared with the reference group. Muscle water increased 10% due to a doubling of the extracellular water fraction.
  
  
  CONCLUSIONS
  Although critically ill patients are a very heterogeneous group from a clinical point of view, there is a remarkable homogeneity in many of the biochemical parameters regardless of the severity of illness and the length of the ICU admission. The three most consistent differences were the skeletal muscle low glutamine concentration, the decrease in protein content, and the increase in extracellular water in the patients.
authors.affiliation: Department of Anesthesiology and Intensive Care, Huddinge University Hospital, Sweden.
authors.forename: L
authors.initials: L
authors.lastname: Gamrin
authors.forename: P
authors.initials: P
authors.lastname: Essén
authors.forename: A M
authors.initials: AM
authors.lastname: Forsberg
authors.forename: E
authors.initials: E
authors.lastname: Hultman
authors.forename: J
authors.initials: J
authors.lastname: Wernerman
mesh_terms: D018806:APACHE; D000273:Adipose Tissue / Q000378:metabolism; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000596:Amino Acids / Q000378:metabolism; D001706:Biopsy; D001834:Body Water / Q000378:metabolism; D016638:Critical Illness; D004247:DNA / Q000378:metabolism; D004573:Electrolytes / Q000378:metabolism; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009124:Muscle Proteins / Q000378:metabolism; D018482:Muscle, Skeletal / Q000378:metabolism* / Q000473:pathology; D010710:Phosphates / Q000378:metabolism; D012313:RNA / Q000378:metabolism
chemical_list: D000596:Amino Acids; D004573:Electrolytes; D009124:Muscle Proteins; D010710:Phosphates; D012313:RNA; D004247:DNA