Sepsis and Systemic Inflammation

Sepsis is a life-threatening organ dysfunction caused by a dysregulated host response to infection. In the surgical patient it can follow an infected wound, an anastomotic leak, an intra-abdominal source, or any breach that introduces infection, and it represents the systemic end of the spectrum that begins with localized inflammation.

Definition

Sepsis is defined as life-threatening organ dysfunction caused by a dysregulated host response to infection; septic shock is a subset in which circulatory and cellular/metabolic abnormalities are profound enough to substantially increase mortality (Singer, 2016).

Scope

This topic covers the contemporary consensus definition of sepsis and septic shock, the underlying concept of a dysregulated host response, the relationship between systemic inflammation and organ dysfunction, and the principle of source control that is central to surgical sepsis. It is a reference entry and does not provide resuscitation protocols or individualized treatment.

Key concepts

• Dysregulated host response to infection
• Organ dysfunction (SOFA)
• Septic shock
• Systemic inflammatory response
• Source control
• Early recognition

Mechanisms

Sepsis arises when the host response to an infection becomes dysregulated, producing widespread inflammation, endothelial and microcirculatory dysfunction, and impaired tissue oxygen utilization that manifests as organ dysfunction. The Sepsis-3 framework shifted the defining feature away from the older systemic inflammatory response criteria toward measurable organ dysfunction, operationalized using the Sequential Organ Failure Assessment score (Singer, 2016). In surgical sepsis, an anatomic focus of infection is often present, so controlling that source, alongside supportive care, is a foundational principle (Evans, 2021).

Clinical relevance

Sepsis is a leading cause of postoperative death and a focus of perioperative surveillance; recognizing organ dysfunction early and identifying a controllable source are central to surgical care. This entry describes how sepsis is defined and conceptualized for reference and education; it is not a basis for individual diagnosis or treatment.

Epidemiology

Sepsis is a major global cause of death across all care settings; a Global Burden of Disease analysis estimated tens of millions of incident cases and millions of deaths annually worldwide, with substantial regional variation (Rudd, 2020).

Evidence & guidelines

The Sepsis-3 consensus provides the current definitions (Singer, 2016), and the Surviving Sepsis Campaign guidelines synthesize the evidence on recognition and management, including the emphasis on timely source control in surgical sepsis (Evans, 2021).

History

Definitions of sepsis evolved from the 1991 systemic inflammatory response syndrome (SIRS)-based criteria, through a 2001 revision, to the 2016 Sepsis-3 consensus that redefined sepsis around organ dysfunction rather than inflammatory signs alone (Singer, 2016). Management has been organized internationally through successive Surviving Sepsis Campaign guidelines (Evans, 2021).

Debates

Are SIRS criteria or organ-dysfunction scores the better basis for defining sepsis?

Sepsis-3 moved the definition from SIRS-based criteria toward measured organ dysfunction, a shift that improved specificity but generated ongoing discussion about sensitivity and applicability across settings.

Key figures

• Mervyn Singer
• Clifford Deutschman
• Derek Angus

Seminal works

• singer-2016
• evans-2021

Frequently asked questions

How is sepsis defined under the Sepsis-3 consensus?

Sepsis is defined as life-threatening organ dysfunction caused by a dysregulated host response to infection, with organ dysfunction identified by a change in the Sequential Organ Failure Assessment (SOFA) score (Singer, 2016).

Why is source control emphasized in surgical sepsis?

When sepsis arises from an identifiable anatomic focus of infection, controlling that source is a foundational principle of management alongside supportive care (Evans, 2021).