5 New Sepsis Definition Criteria

A task force of the Society of Critical Care Medicine and the European Society of Intensive Care Medicine recently published the “Third International Consensus Definitions for Sepsis and Septic Shock” (Sepsis-3). This is big news because it’s the first major update to the definition of sepsis since 2001.

Sepsis-3 isn’t just a couple of minor updates to previously established criteria. Rather, it’s a complete overhaul based on everything experts have learned about the identifications and treatment of sepsis since it was first defined in 1991.

Officially, the new definition of sepsis is “a life-threatening organ dysfunction caused by a dysregulated host response to infection.” When getting the word out to a lay audience, sepsis should be defined as “a life-threatening condition that arises when the body’s response to an infection injures its own tissues and organs.”

Here’s what has changed and how it will affect clinical practice.

1. SIRS is no longer criterion for sepsis.

Using 2 or more systemic inflammatory response syndrome (SIRS) criteria to identify sepsis was “unanimously considered by the task force to be unhelpful.” The Sepsis-3 authors cited a study in Australia and New Zealand that found “1 in 8 patients admitted to critical care units with infection and new organ failure did not have the requisite minimum of 2 SIRS criteria to fulfill the definition of sepsis, yet had protracted courses with significant morbidity and mortality.”

2. SIRS has been replaced with quick Sequential Organ Failure Assessment (qSOFA) score.

The new qSOFA criterion was designed to be a fast and easy tool to help identify sepsis in all health care environments. Unlike SIRS criteria, qSOFA does not require laboratory tests.

A positive qSOFA score should prompt clinicians to look for organ dysfunction, initiate or escalate therapy, and consider referral to critical care.

Positive qSOFA= suspected infection plus ≥2 of the following:

• Altered mental status (Glasgow Coma Scale score <15)
• Systolic blood pressure ≤100 mm Hg
• Respiratory rate ≥22/min

3. SOFA score is now used to clinically characterize septic patients.

SOFA is basically qSOFA’s big sibling. Although it isn’t new, given that it was previously relegated to assessing mortality mostly in intensive care units, it’s now recognized as the gold standard for identifying organ dysfunction in septic patients.

The Sepsis-3 authors deemed SOFA superior to SIRS in predicting hospital mortality, with a SOFA score ≥2 identifying a 2- to 25-fold increased risk of dying. Unfortunately, SOFA is a relatively complex tool, as it entails scoring 6 different organ system markers on a 1-4 scale for each system. An increase in 2 points from baseline signifies a higher risk for in-hospital mortality.

qSOFA was born from SOFA through multivariate logistic regression that showed good predictive value of the simpler-to-attain variables. The following list shows the organ system markers, but not the cutoffs for scoring SOFA.

Positive SOFA= suspected infection plus a change in ≥2 of the following from baseline:

• Platelet count
• Bilirubin
• Glasgow Coma Scale score
• Mean arterial pressure (MAP) or administration of vasopressors with type and dose
• Creatinine or urine output
• PaO₂/FiO₂ ratio and mechanical ventilation

4. Severe sepsis is no more.

“Sepsis” and “septic shock” are the only 2 remaining categories. As the definition of sepsis requires life-threatening organ dysfunction, the categorization of “severe sepsis” has been deemed superfluous and unnecessary.

5. Lactate is now part of septic shock criteria, along with resistant hypotension.

Previously, lactate was regarded as just another marker for organ dysfunction. However, the Sepsis-3 authors pointed to studies that demonstrated that fluid resistant hypotension and a lactate >2 mmol/L was superior in predicting mortality than either marker alone.

It’s important to note that under the new definition of septic shock, a patient must have both hypotension (MAP< 65) and a lactate >2 mmol/L despite adequate fluid resuscitation.

Reference

Singer M, Deutschman CS, Seymour CW, et al. The Third International Consensus Definitions for Sepsis and Septic Shock (Sepsis-3). JAMA. 2016;315(8):801-810. doi:10.1001/jama.2016.0287.