title: Removal characteristics and total dialysate content of glutamine and other amino acids in critically ill patients with acute kidney injury undergoing extended dialysis.
abstract: BACKGROUND
  Acute kidney injury in critically ill patients is associated with the activation of protein catabolism and a negative nitrogen balance. Renal replacement therapy (RRT) aggravates this problem by eliminating a substantial amount of amino acids. However, there is scarce data on the removal characteristics of modern dialysis membranes in extended dialysis.
  
  
  METHODS
  This is a prospective study in 10 extended dialysis sessions using a 1.8-m(2) polysulfone membrane (EMiC2 dialyzer or AV 1000S; FMC, Germany). Blood samples for 19 amino acids were drawn before, during, and after 10 h of extended dialysis (blood/dialysate flow 150 ml/min). In addition, samples for the calculation of dialyzer clearance and samples from the total spent dialysate were measured using a Biochrom 30 amino acid analyzer.
  
  
  RESULTS
  Despite no significant difference in pre- and postdialysis plasma amino acid levels, we found an impressive amount of amino acids in collected spent dialysate, i.e. 10.5 g/10 h of treatment. The dialyzer clearance ranged from 67.6 ml/min for phenylalanine to 140.0 ml/min for valine. The total eliminated masses of the measured amino acids had equal values for both membranes. There was a significant difference between the dialyzer clearance of the investigated membranes for glutamine (AV 1000S: 83.3 ml/min vs. EMiC2: 92.0 ml/min, p = 0.02) and serine (88.8 ml/min vs. 91.8 ml/min, p = 0.005).
  
  
  CONCLUSIONS
  Our data indicate that the modern forms of RRT eliminate amino acids to an extent that has not been met by our nutritional support standards. Especially the removal of glutamine, important for immune function and cell regeneration, might have detrimental effects on the recovery of critically ill patients.
authors.affiliation: Division of Nephrology and Hypertension, Department of Internal Medicine, Hannover Medical School, Hannover, Germany.
authors.forename: Julius J
authors.initials: JJ
authors.lastname: Schmidt
authors.forename: Carsten
authors.initials: C
authors.lastname: Hafer
authors.forename: Julia
authors.initials: J
authors.lastname: Spielmann
authors.forename: Johannes
authors.initials: J
authors.lastname: Hadem
authors.forename: Eva
authors.initials: E
authors.lastname: Schönenberger
authors.forename: Bernhard M W
authors.initials: BM
authors.lastname: Schmidt
authors.forename: Jan T
authors.initials: JT
authors.lastname: Kielstein
mesh_terms: D058186:Acute Kidney Injury / Q000628:therapy*; D000596:Amino Acids / Q000032:analysis* / Q000097:blood; D016638:Critical Illness; D018592:Cross-Over Studies; D015314:Dialysis Solutions / Q000737:chemistry*; D005973:Glutamine / Q000032:analysis; D006801:Humans; D008567:Membranes, Artificial; D008875:Middle Aged; D015596:Nutrition Assessment; D010649:Phenylalanine / Q000032:analysis; D011446:Prospective Studies; D006435:Renal Dialysis / Q000295:instrumentation; D012694:Serine / Q000032:analysis; D013997:Time Factors; D014633:Valine / Q000032:analysis
chemical_list: D000596:Amino Acids; D015314:Dialysis Solutions; D008567:Membranes, Artificial; D005973:Glutamine; D012694:Serine; D010649:Phenylalanine; D014633:Valine