Depletion of plasma antioxidants in surgical intensive care unit patients requiring parenteral feeding: effects of parenteral nutrition with or without alanyl-glutamine dipeptide supplementation.
OBJECTIVE
Antioxidant depletion is common in critically ill patients. This study was designed to determine the effects of parenteral nutrition (PN), with or without glutamine (Gln) supplementation, on systemic antioxidant status in adult patients after major surgery who required PN in the surgical intensive care unit (SICU) setting.


METHODS
Fifty-nine patients in the SICU who required PN after pancreatic surgery or cardiac, vascular, or colonic (non-pancreatic) surgery were randomized in a double-blinded study to receive standard PN (Gln-free) or Gln-supplemented PN (Gln-PN) in which Gln was provided as alanyl-Gln dipeptide. Conventional PN vitamin and mineral doses were administered to all subjects. Plasma concentrations of the antioxidant glutathione (GSH) and the antioxidant nutrients alpha-tocopherol, vitamin C, and zinc were determined at baseline (initiation of study PN) and again after 7 d of study PN. Data were analyzed for the total study cohort and within the pancreatic surgery and non-pancreatic (cardiac, vascular, and colonic) surgery patient subgroups.


RESULTS
Mean plasma antioxidant concentrations were within or slightly below the normal ranges at baseline. However, a larger percentage of patients demonstrated below-normal baseline plasma concentrations of GSH (59%), vitamin C (59%), and zinc (68%), respectively. A smaller percentage of patients exhibited below-normal plasma alpha-tocopherol levels (21%). Study PN significantly improved plasma zinc levels in the entire study group and in each surgical subgroup. Gln-PN significantly improved the change in plasma levels of reduced GSH from baseline to day 7 in the non-pancreatic surgery patients (PN -0.27 microM versus Gln-PN +0.26 microM, P < 0.03).


CONCLUSIONS
Low plasma levels of key antioxidants were common in this group of patients in the SICU despite administration of PN containing conventional micronutrients. Compared with standard PN, Gln-supplemented PN improved plasma GSH levels in patients in the SICU after cardiac, vascular, or colonic operations.
Luo
Menghua
M
Department of Medicine, Emory University School of Medicine, Atlanta, Georgia, USA.
Fernandez-Estivariz
Concepcion
C
Jones
Dean P
DP
Accardi
Carolyn R
CR
Alteheld
Birgit
B
Bazargan
Niloofar
N
Hao
Li
L
Griffith
Daniel P
DP
Blumberg
Jeffrey B
JB
Galloway
John R
JR
Ziegler
Thomas R
TR
D000293:Adolescent; D000328:Adult; D000368:Aged; D000975:Antioxidants / Q000378:metabolism*; D001205:Ascorbic Acid / Q000097:blood; D006348:Cardiac Surgical Procedures; D015331:Cohort Studies; D003106:Colon / Q000601:surgery; D003422:Critical Care; D016638:Critical Illness / Q000628:therapy; D019587:Dietary Supplements; D004151:Dipeptides / Q000008:administration & dosage / Q000494:pharmacology*; D004311:Double-Blind Method; D005260:Female; D005978:Glutathione / Q000097:blood; D006801:Humans; D008297:Male; D008875:Middle Aged; D010179:Pancreas / Q000601:surgery; D010288:Parenteral Nutrition / Q000379:methods*; D011184:Postoperative Period; D013997:Time Factors; D014656:Vascular Surgical Procedures; D015032:Zinc / Q000097:blood; D024502:alpha-Tocopherol / Q000097:blood
D000975:Antioxidants; D004151:Dipeptides; D005978:Glutathione; D024502:alpha-Tocopherol; D015032:Zinc; D001205:Ascorbic Acid; C054122:alanylglutamine