Immunonutrition in Critical Illness

Abstract

Immunonutrition is an emerging therapy that has been the focus of a number of clinical trials. Manipulation of the immune system has the substantial potential to modify disease outcome, particularly in regard to infectious complications. Many studies have examined the effects of nutritional formulas supplemented with arginine, n-3 fatty acids, structured lipids, and nucleotides compared with standard enteral feeding. Unfortunately, because of marked heterogeneity between studies, only limited consensus has been reached. Some randomized studies have shown that immune-enhanced nutritional formulas can reduce postoperative infectious complications in surgical patients with gastrointestinal or head and neck cancer and may be effective when provided preoperatively as well. A few studies show no benefit, but none demonstrated higher infection rates in this population, which is reinforced by the finding from three separate meta-analyses of overall benefit. 1‐3 Therefore, for surgical patients with gastrointestinal/head and neck cancer, the evidence is reasonably strong in favor of the use of immunonutrition, particularly in malnourished patients. In trauma and critically ill patients, the data are less clear, and no overall recommendation in favor of immunonutrition was made recently by Dr Heyland 4 in a review of the evidence (this issue of NCP). There are three large published studies in intensive care unit (ICU) patients, all using the same immune-enhancing diet, which differ in many ways, with only one showing a significant improvement in morbidity and mortality overall. 5‐7 There was a clear trend toward increased mortality with the immune-enhancing diet in the earliest study. 5 Dr