The response to injury or infection in the surgical patient is characterized by diverse endocrine, metabolic, and immunological alterations. If the inciting injury is minor and of limited duration, then wound healing and restoration of metabolic and immune homeostasis occur with relatively minimal intervention. By contrast, major insults to the host are associated with greater alterations in endogenous regulatory processes that, without appropriate and timely intervention, impact negatively on survival or full restoration of cellular and organ function. The spectrum of metabolic and immunological dysfunction arising from major injuries or severe infections is complex. Conceptually, it is beneficial to consider the initial response to injury—be it surgical, traumatic, or infectious—as inherently inflammatory, marked by the activation of cellular processes designed to restore or maintain function within tissues while also promoting the eradication of invading microorganisms. The initial proinflammatory processes are followed by antiinflammatory or counterregulatory processes that are equally important in the restoration of homeostasis to the host (Fig. 4.1).1