Critical Care

SIRS Criteria

Systemic Inflammatory Response Syndrome — ≥2 criteria define SIRS.

When to use: SIRS criteria identify a systemic inflammatory response regardless of cause (infectious or non-infectious). Though superseded by Sepsis-3 for sepsis diagnosis, SIRS remains commonly tested and clinically used as a screening tool.

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Formula

SIRS = ≥2 of: Temp <36 or >38°C | HR >90 | RR >20 or PaCO₂ <32 | WBC <4 or >12 or >10% bands

Key Points for NEET PG

SIRS ≥2 criteria + suspected infection = Sepsis (old Sepsis-2 definition)
Sepsis-3 (2016) replaced SIRS-based sepsis definition with SOFA ≥2 + suspected infection
SIRS can be caused by non-infectious triggers: pancreatitis, burns, trauma, surgery
SIRS + confirmed infection + organ dysfunction = Severe Sepsis (Sepsis-2); now just "Sepsis" in Sepsis-3
Septic shock = Sepsis + vasopressor requirement + lactate >2 mmol/L despite fluid resuscitation

References

Definitions for sepsis and organ failure and guidelines for the use of innovative therapies in sepsis · Chest (1992)

For educational purposes only. Not for clinical decision-making without professional oversight.

“Wherever the art of medicine is loved, there is also a love of humanity.” — Hippocrates