Perfusion status of the critically ill and injured has, in the past, been assessed by indices such as blood pressure (BP), heart rate, and urine output. These indices represent global perfusion and may not reflect regional bloodflow abnormalities. These hypoperfused regions may lead to organ failure and subsequent death. The gastrointestinal (GI) tract remains one of these tissue beds that is extremely sensitive to low-flow states. Gastric tonometry is a noninvasive means in which these early symptoms of low flow may be monitored with early interventions to optimize tissue perfusion and patient outcome.