What defines severe sepsis?

Severe sepsis is characterized specifically by the presence of organ dysfunction as a result of sepsis. The concept of sepsis itself involves a life-threatening organ dysfunction caused by a dysregulated immune response to infection, which can lead to systemic inflammatory response syndrome (SIRS). When there's an indication of organ dysfunction, it elevates the severity of the condition, qualifying it as severe sepsis.

Indicators of organ dysfunction can include altered mental status, impaired urinary output, coagulation abnormalities, and respiratory distress, among others.

While fever, increased heart rate, low blood pressure, and issues with breathing are important clinical features of sepsis and its progression, they don't specifically define severe sepsis. For example, a fever may indicate infection, but it does not inherently reflect the severity of associated organ dysfunction. Similarly, vital sign changes such as heart rate and blood pressure are important, but again, they do not encompass the definition of severe sepsis without the context of organ dysfunction.