SIRS Criteria (Systemic Inflammatory Response Syndrome)

Defines systemic inflammatory response syndrome using temperature, heart rate, respiratory rate, and WBC count. >=2 criteria required.

C

Body temperature in Celsius. >38 C or <36 C = positive.

bpm

Heart rate >90 bpm = positive

breaths/min

RR >20 OR PaCO2 <32 mmHg = positive

mmHg

Optional. PaCO2 <32 mmHg can substitute for RR >20

10^3/mm3

WBC >12,000 or <4,000 or >10% bands = positive

>10% immature neutrophils (bands)

Enter values to assess SIRS criteria

Clinical Notes & Warnings

  • SIRS criteria are non-specific and may be present in many non-infectious conditions (trauma, burns, pancreatitis, surgery).
  • Sepsis-3 (2016) moved away from SIRS to qSOFA + SOFA definitions.
  • SIRS alone does NOT define sepsis (requires suspected/proven infection + organ dysfunction).
  • Severe sepsis = sepsis + organ dysfunction/hypoperfusion.
  • Septic shock = sepsis + hypotension not corrected by fluids + elevated lactate.

SIRS criteria: Temp, HR, RR/WBC. 1991 ACCP/SCCM consensus. Sepsis-3 (2016) redefined sepsis as SOFA >=2 from suspected infection. qSOFA is the quick screening tool.