Enter patient values
Provide vital signs and lab values. PaCO₂ and bands are optional.
Example data
These examples show how different values affect the criteria count.
| Scenario | Temp | HR | RR | PaCO₂ | WBC | Bands | Criteria met | Meets SIRS? |
|---|---|---|---|---|---|---|---|---|
| A | 39.1°C | 112 bpm | 24 /min | — | 14,500 /µL | 6% | 4 | Yes |
| B | 36.8°C | 96 bpm | 18 /min | 30 mmHg | 7.2 ×10⁹/L | — | 2 | Yes |
| C | 37.2°C | 82 bpm | 16 /min | — | 5,800 /µL | — | 0 | No |
Formula used
The calculator evaluates four SIRS criteria and counts how many are met.
- Temperature: met if T > 38°C or T < 36°C.
- Heart rate: met if HR > 90 bpm.
- Respiratory status: met if RR > 20 /min or PaCO₂ < 32 mmHg.
- White cells / bands: met if WBC > 12,000 /µL or WBC < 4,000 /µL or Bands ≥ 10%.
How to use this calculator
- Enter temperature and select the correct unit (°C or °F).
- Enter heart rate and respiratory rate from the latest vitals.
- Optionally add PaCO₂ (ABG/VBG) if available.
- Enter WBC and select unit (/µL or ×10⁹/L).
- Optionally add bands percentage if reported.
- Press Calculate to see criteria, score, and interpretation.
- Use the download buttons to export results for documentation.
Rapid screening purpose
SIRS is a physiologic screening approach built around four bedside domains: temperature, heart rate, respiratory status, and white-cell response. Each domain is scored as met or not met, producing a simple signal that systemic inflammation may be present. Because inputs are routinely collected, it fits ED, ward, and triage workflows.
Thresholds and units
Temperature meets the screen at >38.0°C or <36.0°C (or the equivalent in °F). Heart rate meets at >90 bpm. Respiratory status meets when RR is >20/min or PaCO₂ is <32 mmHg. White cells meet when WBC is >12,000/µL, <4,000/µL, or bands are ≥10%. The calculator converts ×10⁹/L to /µL (1 ×10⁹/L = 1,000/µL) so mixed laboratory reporting remains comparable.
Scoring logic and output
This calculator converts units, then adds four binary checks to produce a total score from 0 to 4. A total of 2 or more is labeled “meets SIRS.” The output lists which rules triggered and shows the thresholds beside the patient’s values. Exports include met/not-met flags, helping document score changes over time.
Interpreting common patterns
A score of 2 often reflects combinations such as fever plus tachycardia, or tachypnea plus leukocytosis. A score of 3–4 is less common and usually indicates multi-system stress or a rapidly evolving process. Importantly, the screen is not specific: trauma, pancreatitis, pulmonary embolism, severe pain, withdrawal, or vigorous exertion can meet criteria. Treat SIRS as a prompt to ask, “What is driving the physiology?”
Monitoring and trending
Serial reassessment matters more than a single snapshot. A drop from 3 to 1 after fluids, antipyretics, or bronchodilators suggests improvement, while a rise from 1 to 3 over several hours signals deterioration. Use the chart to visualize which domain changed—vitals-driven criteria may respond quickly, while WBC trends may lag. Pair the score with oxygen saturation, blood pressure, urine output, mental status, and lactate when available.
Documentation and escalation
Use the exported CSV or PDF to capture the criteria met, the thresholds applied, and time-stamped vitals and labs. If infection is suspected and the score is ≥2, initiate timely clinical evaluation, cultures when appropriate, and early therapy per local protocols. If infection is not suspected, search for alternative inflammatory drivers, repeat measurements, and communicate the trend clearly during handoffs.
FAQs
1) What does a SIRS score of 2 mean?
It means at least two of the four screening criteria are met. This can indicate systemic inflammation and should trigger clinical assessment, trend review, and consideration of underlying causes, including infection, but it is not diagnostic by itself.
2) Why can SIRS be positive without infection?
Many conditions raise temperature, pulse, breathing rate, or WBC. Examples include trauma, surgery, pancreatitis, burns, dehydration, pulmonary embolism, and medication effects. SIRS is sensitive for inflammation, not specific for infection.
3) Do I need PaCO₂ and bands to calculate?
No. The calculator works with vitals and WBC alone. Add PaCO₂ if an ABG/VBG is available and bands if reported, because either can meet a criterion and change the total score.
4) How are units converted in the calculator?
Temperature entered in °F is converted to °C for threshold checks. WBC entered in ×10⁹/L is converted to /µL using 1 ×10⁹/L = 1,000/µL. The display keeps both the original and converted values.
5) How often should values be reassessed?
Use local protocols and clinical judgment. In unstable patients, reassess vitals frequently and repeat labs as indicated. Trending changes over hours is often more informative than a single measurement.
6) Does meeting SIRS automatically mean sepsis?
No. Sepsis requires suspected or confirmed infection plus evidence of organ dysfunction, depending on definitions used. SIRS can be a useful early signal, but it must be interpreted with the full clinical picture.