SIRS Criteria
Systemic Inflammatory Response Syndrome identification
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Why use it
Rapid bedside identification of systemic inflammation. Still used in many hospital sepsis screening protocols and EMR alerts. Historical importance — understanding SIRS terminology remains essential.
About
SIRS criteria identify patients with systemic inflammatory response. Meeting ≥ 2 of 4 criteria defines SIRS. While the Sepsis-3 definitions (2016) moved away from SIRS for defining sepsis, SIRS remains widely used in clinical practice, many EMR alert systems, and is still part of several clinical protocols.
When to use
- Screening for systemic inflammation at bedside
- Part of hospital sepsis alert systems
- Trauma and post-operative monitoring
- Pancreatitis severity assessment (SIRS-based criteria)
Formula
Pearls & pitfalls
- SIRS ≥ 2 + infection source was the pre-2016 definition of sepsis.
- Sepsis-3 (2016) replaced SIRS with SOFA for sepsis definition, but SIRS is still widely used clinically.
- SIRS is sensitive but NOT specific for infection — many non-infectious conditions trigger SIRS.
- Up to 12% of ICU patients with sepsis do NOT meet SIRS criteria — it should not be used to exclude sepsis.
- Post-surgical patients commonly meet SIRS criteria without infection.
Next steps
SIRS ≥ 2 with suspected infection: Evaluate for sepsis. Obtain cultures, lactate, and initiate sepsis workup. SIRS without infection: Consider non-infectious causes (pancreatitis, burns, trauma, post-surgical, transfusion reaction).
Evidence
Defined by the 1991 ACCP/SCCM Consensus Conference (Bone et al., Chest 1992). Superseded for sepsis definition by Sepsis-3 (2016) but remains in widespread clinical use for screening.
References
- Bone RC et al. Definitions for sepsis and organ failure and guidelines for the use of innovative therapies in sepsis. Chest. 1992;101(6):1644-1655. — link