Pathophysiology: Nutrition in Illness

This chapter outlines the differences in metabolic responses to starvation, and to starvation complicated by acute illness. In starvation there is conservation of body stores and feeding will increase anabolism and repletion of stores, whilst in starvation plus acute illness, the changes in counter-regulatory hormonal control induce mobilization of stores and feeding will increase catabolism and not replenish body stores. This is critical to understand as it accounts for many of the complications of interventional feeding in the critically ill, where feeding in a previously well-nourished patient with good body stores will exacerbate protein oxidative losses and hyperglycemia, and feeding in a nutritionally depleted patient will support the flow of nutrients to vital organs, but will not replenish body stores until the stress of acute illness abates and the regulatory hormonal control switches back to net anabolism.