Clinical Effects of Postoperative Parenteral Glutamine-Dipeptide Supplementation in Surgical Intensive Care Unit Patients: A Systematic Review and Meta-Analysis

Background: Glutamine plays a vital role as an energy substrate the inflammatory response, prevention of organ injury and renal acid buffering. Parenteral glutamine supplementation could reduce in-hospital and ICU morbidity and mortality. Objective: Aim of this systematic review and meta-analysis is to investigate the effects of parenteral administration of GLN in adult surgical critically ill ICU patients. Study selection: Two-arm studies about adult surgical ICU patients undergoing postoperative glutamine-enriched Endpoints: Primary endpoint was in-hospital outcome (mortality, length of stay, length of mechanical ventilation). Secondary endpoint was the evaluation of nosocomial infections. Results: According to PRISMA (R) 2020 flow diagram, eight randomized controlled trials were included for a total of 603 patients. No significant differences about in-hospital and ICU mortality were found (p=0.16 and p=0.53, respectively). Parenteral glutamine-supplementation was associated with a reduction of hospitalization (p=0.02), without influencing nor ICU stay (p=0.35) neither postoperative mechanical ventilation (p=0.18). Finally, dipeptide administration did not reduced cumulative incidence of nosocomial infections (p=0.41); however, a protective role for postoperative pneumonia was reported (p=0.05). Conclusions: Excepting for a reduction in hospital stay and incidence of nosocomial pneumonia, glutamine-dipeptide parenteral supplementation does not add any benefit in surgical ICU patients.