Sepsis Screening Calculator (SIRS, qSOFA, SOFA)

Screen for sepsis using SIRS, qSOFA, and SOFA scoring systems. Includes organ dysfunction assessment, septic shock classification, and mortality estimation.

About the Sepsis Screening Calculator (SIRS, qSOFA, SOFA)

Sepsis is a life-threatening organ dysfunction caused by a dysregulated host response to infection. It affects over 49 million people worldwide annually and accounts for nearly 20% of all global deaths. Early recognition and treatment — particularly antibiotics within the first hour — dramatically improve survival. The **Surviving Sepsis Campaign** estimates that each hour of antibiotic delay increases mortality by 4–7%.

The definition and screening of sepsis has evolved through three major iterations. **SIRS** (Systemic Inflammatory Response Syndrome) uses four simple bedside criteria (temperature, heart rate, respiratory rate, WBC count) — meeting 2 or more suggests systemic inflammation. While highly sensitive, SIRS is non-specific and can be positive in many non-infectious conditions. The **Sepsis-3 (2016)** definition refined the concept: sepsis is now defined as a suspected or documented infection with an acute increase in **SOFA score ≥ 2**, reflecting organ dysfunction rather than inflammation alone.

For bedside screening, **qSOFA** (quick SOFA) uses just three clinical parameters — systolic BP ≤ 100, respiratory rate ≥ 22, and altered mentation (GCS < 15). A qSOFA ≥ 2 prompts further assessment for organ dysfunction. **Septic shock** is the most severe manifestation: sepsis with persistent hypotension requiring vasopressors AND lactate > 2 mmol/L despite adequate fluid resuscitation, carrying a mortality rate exceeding 40%. This calculator provides simultaneous SIRS, qSOFA, and SOFA assessment for comprehensive sepsis screening and severity classification.

Why Use This Sepsis Screening Calculator (SIRS, qSOFA, SOFA)?

Sepsis kills 11 million people annually. Early screening with SIRS, qSOFA, and SOFA scoring systems enables rapid recognition and life-saving treatment initiation. Keep these notes focused on your operational context. Tie the context to the calculator’s intended domain. Use this clarification to avoid ambiguous interpretation. Align this note with review checkpoints. Apply this where interpretation shifts by use case.

How to Use This Calculator

Enter vital signs: temperature, heart rate, respiratory rate, WBC, systolic BP, and GCS.
Enter organ function labs: lactate, creatinine, platelets, bilirubin, PaO₂, and FiO₂.
Use clinical presets for non-sepsis, SIRS, sepsis, and septic shock scenarios.
Review all three scores: SIRS criteria, qSOFA, and full SOFA with organ-level breakdown.
The classification integrates all scores with septic shock identification.
Reference the SOFA scoring table for organ-specific point assignment.

Formula

SIRS: ≥ 2 of [Temp > 38 or < 36°C, HR > 90, RR > 20, WBC > 12 or < 4 ×10³/μL]. qSOFA: ≥ 2 of [SBP ≤ 100, RR ≥ 22, GCS < 15]. SOFA: Sum of 6 organ system scores (0–4 each) = 0–24 total. Sepsis-3: Infection + ΔSOFA ≥ 2. Septic Shock: Sepsis + vasopressors needed + lactate > 2 despite fluids.

Example Calculation

Result: SIRS 4/4, qSOFA 2/3, SOFA 6 — Sepsis

All 4 SIRS criteria met. qSOFA 2 (SBP ≤ 100, RR ≥ 22). SOFA 6 (renal 2, coag 1, liver 1, resp 2) with infection suspected. Meets Sepsis-3 criteria.

Tips & Best Practices

Time is critical: every hour of antibiotic delay increases mortality by 4–7%.
Lactate should be measured within 1 hour and repeated at 2–4 hours if initially elevated.
qSOFA is most useful outside the ICU — in the ED or on the wards — for early detection.
A single SOFA score is less useful than the trend (ΔSOFA) — baseline organ function matters.
Procalcitonin (PCT) can help distinguish bacterial from viral infection but should not delay treatment.

Practical Guidance

Use consistent units, verify assumptions, and document conversion standards for repeatable outcomes.

Common Pitfalls

Most mistakes come from mixed standards, rounding too early, or misread labels. Recheck final values before use. ## Practical Notes

Use this for repeatability, keep assumptions explicit. ## Practical Notes

Track units and conversion paths before applying the result. ## Practical Notes

Use this note as a quick practical validation checkpoint. ## Practical Notes

Keep this guidance aligned to expected inputs. ## Practical Notes

Use as a sanity check against edge-case outputs. ## Practical Notes

Capture likely mistakes before publishing this value. ## Practical Notes

Document expected ranges when sharing results.

Frequently Asked Questions

What is the difference between SIRS and sepsis?

SIRS is the systemic inflammatory response (non-specific — can be from surgery, burns, pancreatitis). Sepsis requires suspected or confirmed infection PLUS organ dysfunction (SOFA ≥ 2).

When should I use qSOFA vs SOFA?

qSOFA is a bedside screening tool (3 criteria, no labs needed). If qSOFA ≥ 2, perform full SOFA assessment. SOFA requires lab values and is more comprehensive for ICU patients.

What is the hour-1 bundle?

The Surviving Sepsis Campaign Hour-1 bundle: measure lactate, obtain blood cultures, start broad-spectrum antibiotics, begin 30 mL/kg crystalloid for hypotension or lactate ≥ 4, and start vasopressors if needed — all within the first hour. Use this as a practical reminder before finalizing the result.

How is septic shock defined?

Sepsis-3 defines septic shock as: sepsis + need for vasopressors to maintain MAP ≥ 65 + lactate > 2 mmol/L despite adequate fluid resuscitation. In-hospital mortality exceeds 40%.

Can a patient have sepsis with a normal WBC?

Yes. Up to 20% of sepsis patients have normal WBC counts. Bandemia (> 10% bands) or immunosuppression can cause sepsis without leukocytosis. Use qSOFA and SOFA regardless of WBC.

What is the significance of lactate > 2?

Lactate > 2 mmol/L indicates tissue hypoperfusion and is an independent predictor of mortality. Serial lactate measurements (targeting > 20% clearance in 2–4 hours) guide resuscitation adequacy.