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The objective of this study was to evaluate the impact of perioperative glutamine-supplemented parenteral nutrition (GLN-PN) on clinical outcomes in patients undergoing abdominal surgery. MEDLINE, EMBASE, and the Cochrane Controlled Clinical Trials Register were searched to retrieve the eligible studies. Eligible studies were randomized controlled trials (RCTs) that compared the effect of GLN-PN and standard PN on clinical outcomes in patients undergoing abdominal surgery. Clinical outcomes of interest were postoperative mortality, length of hospital stay, morbidity of infectious complication, and cumulative nitrogen balance. Statistical analysis was conducted by RevMan 5.0 software from the Cochrane Collaboration. Sixteen RCTs with 773 patients were included in this meta-analysis. The results showed a significant decrease in the infectious complication rates of patients undergoing abdominal surgery receiving GLN-PN (risk ratio [RR], 0.48; 95% confidence interval [CI], 0.32 to 0.72; P = 0.0004). The overall effect indicated glutamine significantly reduced the length of hospital stay in the form of alanyl-glutamine (weighted mean difference [WMD], -3.17; 95% CI, -5.51 to -0.82; P = 0.008) and in the form of glycyl-glutamine (WMD, -3.40; 95% CI, -5.82 to -0.97; P = 0.006). A positive effect in improving postoperative cumulative nitrogen balance was observed between groups (WMD, 7.40; 95% CI, 3.16 to 11.63; P = 0.0006), but no mortality (RR, 1.52; 95% CI, 0.21 to 11.9; P = 0.68). Perioperative GLN-PN is effective and safe to shorten the length of hospital stay, reduce the morbidity of postoperative infectious complications, and improve nitrogen balance in patients undergoing abdominal surgery.
GLUTAMINE (GLN) IS THE most abundant free amino acid in humans, contributing more than 50 per cent of the body's free amino acid pool.1 It is principally synthesized in skeletal muscle from the catabolism of branched-chain amino acids. In conditions of an excessive tissue demand of glutamine during episodes of trauma, major surgery, and other catabolic stress situations, endogenous glutamine production is insufficient to meet the rapidly increased requirement, and glutamine depletion occurs.2-4 The fall in glutamine levels may suggest that glutamine becomes a ''conditionally essential'' amino acid.5
Glutamine is particularly important as a precursor of glutathione and thus in antioxidant defense.6 Glutamine also plays a role in intracellular signaling, enhances heat-shock protein expression,7 prevents apoptosis in injury, and attenuates hyperinflammation.8 There is some evidence to...