Glutamine supplementation in critical illness: evidence, recommendations, and implications for clinical practice in burn care.

Glutamine is considered a conditionally essential amino acid in metabolic stress. Depletion of plasma and muscle glutamine is observed in acute burn injury and contributes to muscle wasting, weight loss, and infection. In critical illness, supplementation has been shown in patients to minimize these effects and reduce the rate of mortality and length of stay. The evidence for glutamine use and its implications for burn care practice are considered here. Work published to February 2006, which investigated enteral and parenteral glutamine supplementation in burns and critical care, is reviewed. Randomized controlled trials in burns, systematic reviews, and nutrition support practice guidelines are considered. Randomized controlled trials in burns suggest significant clinical benefit in terms of morbidity, mortality, and length of stay but are limited by sample size. Parenteral glutamine studies are under-represented. Systematic reviews and practice guidelines generally support glutamine supplementation in critical illness but vary in the level of recommendations for its use in burns. There also are features unique to burn injury that require consideration. Patients with severe burns or inhalation injury may have a prolonged critical illness phase. In large burns, inflammation and hypermetabolism may persist well beyond 4 weeks of injury. The justification and safety of long-term glutamine supplementation is yet to be established. The outlook for glutamine therapy in burns is promising. However, to strengthen recommendations for routine therapy in burns, further research focusing on larger-scale enteral glutamine studies, parenteral glutamine supplementation, and long-term use of the substrate is necessary.