Sepsis and the related “systemic inflammatory response syndrome” (SIRS) are the result of spillover of an inflammatory process into the systemic circulation. The inflammatory response is often (but not always) due to infection; an infective source is identified in approximately 65% of patients with sepsis, but blood cultures are only positive in 25%.
Sepsis can be rapidly progressive and if not treated promptly can result in end organ damage, multiple organ failure and death.
The incidence of sepsis has increased steadily over recent years; over 50% of ICU patients develop SIRS during the course of their admission. Worldwide incidence is 1.8 million cases annually and in the EU the incidence is about 90 cases per 100 000. Low rates of recognition, diagnosis and a tendency to record the causative pathology (e.g., pneumonia) rather than the systemic condition mean that this figure is likely to be an underrepresentation.
It is estimated that sepsis kills more people in the developed world per year than heart disease or stroke.