Despite its initial description as primarily a pulmonary disorder, the acute respiratory distress syndrome (ARDS) has been recognized as one component of a systemic disorder associated with microvascular permeability and widespread organ involvement that often afflicts the gastrointestinal tract. Although a healthy gut is an important defense for the body, its unique vascular anatomy and its predisposition toward ischemia and mucosal hypoxia put the gastrointestinal tract at high risk of injury during the course of the systemic inflammatory response syndrome. Once the mucosa is damaged and host defenses break down translocation of bacteria and bacterial toxins is likely to contribute to the inflammation associated with sepsis and ARDS. Gastric tonometry offers a potentially useful mechanism to monitor regional perfusion and oxidative metabolism in the splanchnic vascular bed. Many studies have shown that tonometry can assist the clinician on prognostic assessment of patients. Several studies also have demonstrated improved patient outcome when therapies aimed to protect the GI tract are aggressively pursued with tonometric guidance.