Infectious Diseases

SIRS, Sepsis, and Septic Shock Criteria Calculator

SIRS, Sepsis, and Septic Shock Criteria Calculator

SIRS & Sepsis Criteria

Defines the severity of sepsis and septic shock. Used to screen and guide early, aggressive resuscitative measures. For patients ≥18 years.
SIRS Criteria (Systemic Inflammatory Response Syndrome)
Temperature
>38°C (100.4°F) OR <36°C (96.8°F)
Heart Rate
>90 beats per minute
Respiratory Rate or PaCO₂
RR >20 breaths/min OR PaCO₂ <32 mm Hg
White Blood Cell Count (WBC)
>12,000/mm³, <4,000/mm³, OR >10% bands
Sepsis & Shock Progression
Suspected Source of Infection
Is there a suspected or present source of infection?
Organ Dysfunction / Hypoperfusion
Lactic acidosis, SBP <90, or SBP drop ≥40 mm Hg of normal
Refractory Hypotension
Hypotension present despite adequate fluid resuscitation
Multiple Organ Dysfunction (MODS)
Evidence of ≥2 organs failing
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SIRS
Criteria Met
Evaluating…
Please answer all criteria to view full recommendations.
DiagnosisCriteria Requirements
Normal / Excluded0-1 SIRS criteria met.
SIRS≥ 2 SIRS criteria met. Screen for infection.
SepsisSIRS + Suspected source of infection.
Severe SepsisSepsis + Organ dysfunction / Hypoperfusion.
Septic ShockSevere Sepsis + Hypotension despite fluid resuscitation.
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Lactate Driven Care: Screen for severe sepsis by obtaining a lactate level. A lactate ≥2 mmol/L is considered elevated. Aggressive management with broad-spectrum antibiotics and IVF should be considered.
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Time is Critical: The Surviving Sepsis Campaign Guidelines recommend initiation of antimicrobials within 1 hour from the time of recognition of severe sepsis/septic shock, or within 3 hours of arrival.
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Clinical Judgment: A significant number of patients (e.g., young, healthy viral illnesses) may meet criteria for SIRS or Sepsis but may not require aggressive interventions if well-appearing. Do not rely solely on scores.
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Hemodynamic Instability: If a patient has suspected infection AND hemodynamic instability, treat immediately for septic shock. Do not delay management waiting for lab values (WBC, lactate).
For clinical decision support only. Sepsis definitions are evolving (e.g., Sepsis-3 Consensus). Institutional protocols may vary. Consult your local guidelines.
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):1644-55.
  • Levy MM, et al. 2001 SCCM/ESICM/ACCP/ATS/SIS International Sepsis Definitions Conference. Crit Care Med. 2003;31(4):1250-56.
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Reviewed by ·
Semahattin Serkan Sezer MD

Pulmonologist and Intensive Care Specialist specializing in clinical informatics and the development of evidence-based decision support tools for healthcare professionals.