Giving glutamine supplements to critically ill adults
Glutamine is a non-essential amino acid which is abundant in the healthy human body. There are studies reporting that muscle and plasma glutamine levels are reduced in patients with critical illness, or following major surgery, suggesting that the body’s demand for glutamine is increased in these situations. In the past decade, several clinical trials have examined the effects of glutamine supplementation in patients with critical illness or receiving surgery, and a systematic review of this clinical evidence suggested that giving glutamine to these patients may reduce infection and mortality rates. However, two recent large-scale clinical trials, published in 2011 and 2013, did not find any beneficial effects of glutamine supplementation in patients with critical illness.
In this review, we searched the available literature until May 2013 and included studies which compared the outcomes with glutamine supplementation and without in adults with a critical illness or undergoing elective major surgery. We included 57 articles from 53 randomized controlled studies in this review. These 53 studies enrolled a total of 4671 patients with critical illness or undergoing elective major surgery. The risk of mortality, length of intensive care unit stay and the incidence of side effects were not significantly different between those given glutamine and those who were not. However, our findings showed that the risk of infectious complications in patients who were given glutamine was 79% of the risk for those who were not. In other words, 12 patients need to be supplemented with glutamine to prevent one case of infection. This result needs to be interpreted cautiously as the quality of evidence for infectious complications was moderate. The funnel plot for this outcome suggested that smaller studies with outcomes favouring non-supplemented patients have not been published, and further research is likely to have an impact on the estimate of effect for this outcome. The findings from this review also suggested that the average length of hospital stay in critically ill or surgical patients supplemented with glutamine was 3.46 days shorter than for patients without glutamine supplementation. This result should also be treated with care as there was substantial heterogeneity between these studies. We found in this review that the mean number of days on mechanical ventilation was 0.69 days shorter in patients with glutamine supplementation than for patients without glutamine supplementation.