What are the clinical criteria for systemic inflammatory response syndrome (SIRS) in sepsis/septic shock?

Updated: Oct 07, 2020
  • Author: Andre Kalil, MD, MPH; Chief Editor: Michael R Pinsky, MD, CM, Dr(HC), FCCP, FAPS, MCCM  more...
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Answer

Criteria for SIRS are considered to be met if at least 2 of the following 4 clinical findings are present:

  • Temperature higher than 38°C (100.4°F) or lower than 36°C (96.8°F)

  • Heart rate (HR) higher than 90 beats/min

  • Respiratory rate (RR) higher than 20 breaths/min or arterial carbon dioxide tension (PaCO2) lower than 32 mm Hg

  • White blood cell (WBC) count higher than 12,000/µL or lower than 4000/µL or with 10% immature (band) forms

Note that a patient can have a severe infection without meeting SIRS criteria; conversely, SIRS criteria may be present in the setting of many other illnesses not caused by an infectious process (see the image below).

Venn diagram showing the overlap of infection, bac Venn diagram showing the overlap of infection, bacteremia, sepsis, systemic inflammatory response syndrome (SIRS), and multiorgan dysfunction.

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