Sepsis is an overreaction by the immune system to infection (usually bacterial, but could be viral, fungal, or parasitic). It is a systemic inflammatory response, which can be life-threatening.
A weakened immune system, certain chronic disorders, an artificial joint or heart valve, and certain heart valve abnormalities increase the risk for sepsis. Sepsis has been reported to be the most common cause of death in the noncoronary intensive care unit. Note that it is sepsis (the immune system's response) that is usually the cause of death and not the infection. Therefore, it is crucial that the recognition of sepsis be made as quickly as possible. Delay in identifying sepsis limits the effectiveness of treatment.
Sepsis includes two or more of the following symptoms:
- A body temperature >38°C (100.4°F) or <36°C (96.8°F)
- A heart rate >90 beats/minute
- Respiratory rate >20 breaths/minute
- An alteration in the white blood cell (WBC) picture, such as a count >12.0 x 109/L or <4.0 x 109/L or >10% immature neutrophils
However, these inflammatory responses may also occur in the absence of infection, a condition termed systemic inflammatory response syndrome (SIRS). When the cause of the systemic inflammatory response is infection, the condition is defined as sepsis.