In 1991, the American College of Chest Physicians and the American College of Critical Care Medicine, first introduced the concept of systemic inflammatory response syndrome with two or more of the following clinical manifestations: First, body temperature greater than 38°C or less than 36°C. Second, heart rate greater than 94 beats per minute. Third, shortness of breath, respiratory rate greater than 20 breaths/min or hyperventilation with partial pressure of carbon dioxide less than 32 mm Hg. Fourth, white blood cell count greater than 12 × 10^9/L and less than 4 × 10^9/L, or total white blood cell count normal but neutrophilic rod nucleated granulocytes, that is, immature neutrophils greater than 10%. The causes of systemic inflammatory response syndrome include progressive trauma, massive burns, acute pancreatitis, malignancy, and many other non-infectious factors, in addition to concurrent and distant infections. Among them, the systemic inflammatory response syndrome caused by definite or suspected infections is also called sepsis.