The 2016 ESPEN Arvid Wretlind lecture: The gut in stress.

The gut has a major influence on the course of the human stress response in critical illness for several reasons; the quantity of its immune tissue, the extent of interface with the external environment, the expanse of the microbiome, and its access to the systemic circulation. In critical illness, it is not uncommon to lose mucosal barrier function, which exposes the host to the downside effects of luminal contents and epithelial cell regulation. In that setting, the microbiome is converted to a pathobiome, upregulation of metabolic and immune responses occurs, and homeostatic defense systems are compromised. Awareness of this process mandates that greater attention be given to the interplay between the gut and systemic responses, and that modulation of the gastrointestinal tract be considered in every therapeutic intervention in the critical care setting.