DEFINITIONS

Sepsis is a complex syndrome comprising a constellation of systemic symptoms and signs in response to infection, including inflammatory, pro-coagulant, and immunosuppressive events. Septic shock occurs when there is significant hypotension in the presence of sepsis. The definitions and diagnostic criteria for sepsis and related conditions were developed in 1991 at a consensus conference sponsored jointly by the American College of Chest Physicians and the Society for Critical Care Medicine and reviewed by the 2001 International Sepsis Definitions Conference (sponsored by the Society of Critical Care Medicine, European Society of Critical Care Medicine, American College of Chest Physicians, American Thoracic Society, and the Surgical Infections Society). Apart from expanding the list of signs and symptoms of sepsis to reflect clinical bedside experience, the definitions remained unchanged. The sepsis-related terminology and definitions are presented in Table 2.1; the diagnostic criteria for sepsis presented in Table 2.2 have been updated by the Conference to include a variety of signs of systemic inflammation in response to infection. This international group proposed a classification scheme for sepsis that stratifies patients based on their predisposing conditions, the nature and extent of the insult (infection), the host response, and the degree of concomitant organ dysfunction (acronym PIRO). This concept will have to be further tested and refined before it can be routinely applied in clinical practice.