Sepsis Definitions

Author: Jeremy Voros, MD
Updated: 12/1/2017

Sepsis Definitions

In 2015 the Centers for Medicare and Medicaid Services (CMS) adopted the Sepsis Bundle Project, which is a quality improvement project aimed at reducing sepsis mortality by increasing compliance with national guidelines. But the CMS definitions of sepsis, differ from those is prominent trials (ProCESS, ARISE, ProMISE), and have since diverged from the Surviving Sepsis Campaign definitions, which may be different from your hospital guidelines! This card will help you keep it all straight.

CMS Definitions

These are the definitions tied to reimbursement, and likely the measures used to establish your hospital guidelines.

CMS Term Definition
Sepsis 2 SIRS criteria plus suspected infection
Severe Sepsis Sepsis plus 1 or more signs of organ dysfunction
Septic Shock Severe sepsis plus either: sepsis-induced hypoperfusion persisting despite adequate fluid resuscitation or lactate > 4 mmol/L

SIRS Criteria

  • Temp >38°C (100.4°F) or < 36°C (96.8°F)
  • Heart rate > 90
  • Respiratory rate > 20 or PaCO₂ < 32 mm Hg
  • WBC > 12,000/mm³, < 4,000/mm³, or > 10% bands

Organ Dysfunction Criteria

  • SBP < 90 mmHg, or MAP < 65 mmHg, or SBP decrease of > 40 mmHg from known baseline
  • Creatinine > 2.0 mg/dL, or urine output < 0.5 mL/kg/hour for 2 hours
  • Bilirubin > 2 mg/dL (34.2 mmol/L)
  • Platelet count < 100,000
  • INR > 1.5 or aPTT > 60 sec
  • Lactate > 2 mmol/L (18.0 mg/dL)

Sepsis-induced Hypoperfusion Criteria

Any one of:

  • SBP < 90 mmHg
  • MAP < 70 mmHg
  • SBP decrease of > 40 mmHg or > 2 standard deviations from normal for age or known baseline

Study Definitions

The 3 most recent and most prominent studies investigating resuscitation in septic shock were ProCESS, ARISE and ProMISE. They all share a common definition of septic shock, but do not directly address what CMS calls "severe sepsis."

Their definition differs from CMS on the MAP cutoff for hypoperfusion. CMS sets a MAP cutoff of < 70 mmHg, while these studies use a MAP < 65 mmHg.

Study Term Definition
Sepsis not defined
Severe Sepsis not defined
Septic Shock 2 SIRS criteria plus either: refractory hypotension (SBP <90 mmHg or MAP <65 mmHg, despite resuscitation with at least 1 liter of intravenous fluids within 60 minutes) or hyperlactatemia (blood lactate level, ≥ 4 mmol per liter

Surviving Sepsis Campaign (SSC) and Sepsis-3

The latest 2016 guidelines from the prominent international working group are based on previously established definitions of sepsis, i.e. the CMS definitions.

However also in 2016, the Third International Consensus Definitions for Sepsis and Septic Shock (Sepsis-3) were published in the Journal of the American Medical Association. SSC has indicated their guidelines will begin transitioning to these new definitions.

Notably, the Sepsis-3 definitions do away with the term "severe sepsis".

Sepsis-3 Term Definition
Sepsis Life-threatening organ dysfunction caused by a dysregulated host response to infection
Severe Sepsis No longer defined
Septic Shock Sepsis with persistent hypotension requiring vasopressors to maintain MAP ≥ 65 mm Hg and a serum lactate level > 2 mmol/L despite adequate volume resuscitation

Organ dysfunction can be identified as an acute change in Sequential Organ Failure Assessment (SOFA) score ≥ 2 points due to the infection.

Patients with suspected infection who are likely to have a prolonged ICU stay or to die in the hospital can be promptly identified at the bedside with qSOFA (quick SOFA).

qSOFA Criteria

Any one of:

  • GCS < 15
  • SBP ≤ 100 mmHg
  • Respiratory rate > 21

SOFA Score

The total Sequential Organ Failure Assessment (SOFA) score is the sum of scores for each organ system. A nice calculator can be found at MDCalc.


  • Severe Sepsis and Septic Shock: Management Bundle. National Quality Forum website Updated October 5, 2012. Accessed November 29, 2017.
  • Yealy DM, Kellum JA, Huang DT, et al. A randomized trial of protocol-based care for early septic shock. N Engl J Med. 2014;370(18):1683-93. [PubMed]
  • Peake SL, Delaney A, Bailey M, et al. Goal-directed resuscitation for patients with early septic shock. N Engl J Med. 2014;371(16):1496-506. [PubMed]
  • Mouncey PR, Osborn TM, Power GS, et al; ProMISe Trial Investigators: Trial of early, goal-directed resuscitation for septic shock. N Engl J Med 2015; 372:1301–1311 [PubMed]
  • Singer M, Deutschman CS, Seymour CW, et al. The Third International Consensus Definitions for Sepsis and Septic Shock (Sepsis-3). JAMA. 2016;315(8):801-10. [PubMed]