What is the latest definition of sepsis (Systemic Inflammatory Response Syndrome)?

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Last updated: May 18, 2025View editorial policy

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From the Guidelines

The latest sepsis definition, established in 2016 as Sepsis-3, defines sepsis as life-threatening organ dysfunction caused by a dysregulated host response to infection, as recently reaffirmed in 2024 by the acr appropriateness criteria® sepsis 1.

Key Points

  • Sepsis is defined as life-threatening organ dysfunction caused by a dysregulated host response to infection.
  • The Sequential Organ Failure Assessment (SOFA) score is used to identify organ dysfunction, with a patient considered to have sepsis when they have a suspected or documented infection plus an acute increase in SOFA score of 2 or more points.
  • For quick bedside screening, the qSOFA score can be used, which includes three criteria: altered mental status, systolic blood pressure ≤100 mmHg, and respiratory rate ≥22 breaths per minute.
  • Septic shock is defined as sepsis with persisting hypotension requiring vasopressors to maintain MAP ≥65 mmHg and having a serum lactate >2 mmol/L despite adequate fluid resuscitation.

Rationale

The updated definition of sepsis, as outlined in the Sepsis-3 consensus, emphasizes the importance of organ dysfunction in the diagnosis of sepsis, rather than just the presence of infection with systemic inflammatory response 1. This change was made to improve early recognition of sepsis and to better predict hospital mortality compared to previous definitions. The use of the SOFA score and qSOFA score provides a standardized approach to identifying patients with sepsis and septic shock, allowing for timely and effective treatment.

Clinical Implications

The latest sepsis definition has significant implications for clinical practice, including the need for prompt recognition and treatment of sepsis, as well as the use of standardized criteria for diagnosis and management. By using the SOFA score and qSOFA score, clinicians can quickly identify patients with sepsis and septic shock, and provide appropriate treatment to improve outcomes.

From the Research

Latest Sepsis Definition

  • The latest definition of sepsis is life-threatening organ dysfunction caused by a dysregulated host response to infection 2, 3, 4, 5, 6.
  • This definition was introduced in 2016 by the Third International Consensus Definitions for Sepsis and Septic Shock (Sepsis-3) 2.
  • The definition of septic shock is a subset of sepsis in which particularly profound circulatory, cellular, and metabolic abnormalities are associated with a greater risk of mortality than with sepsis alone 2, 5.

Clinical Criteria

  • Organ dysfunction can be represented by an increase in the Sequential Organ Failure Assessment (SOFA) score of 2 points or more, which is associated with an in-hospital mortality greater than 10% 2.
  • Septic shock can be clinically identified by a vasopressor requirement to maintain a mean arterial pressure of 65 mm Hg or greater and serum lactate level greater than 2 mmol/L (>18 mg/dL) in the absence of hypovolemia 2, 5.
  • The quickSOFA (qSOFA) score can be used to identify patients with suspected infection who are likely to develop sepsis, and is defined as having at least 2 of the following clinical criteria: respiratory rate of 22/min or greater, altered mentation, or systolic blood pressure of 100 mm Hg or less 2, 3.

Diagnosis and Management

  • The diagnosis of sepsis involves basic laboratory tests, cultures, imaging studies as indicated, and sepsis biomarkers such as procalcitonin and lactate levels 5.
  • Initial management of sepsis includes fluid resuscitation, antimicrobial therapy, and vasopressor therapy if necessary 5.
  • The latest guidelines recommend starting antimicrobials within one hour of presentation, although this is controversial 5.

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

Changing Definitions of Sepsis.

Turkish journal of anaesthesiology and reanimation, 2017

Research

A new definition of sepsis (Sepsis-3) - aims, advantages, and controversies.

Epidemiologie, mikrobiologie, imunologie : casopis Spolecnosti pro epidemiologii a mikrobiologii Ceske lekarske spolecnosti J.E. Purkyne, 2018

Research

Sepsis: Diagnosis and Management.

American family physician, 2020

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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