From the Guidelines
The Systemic Inflammatory Response Syndrome (SIRS) criteria include temperature >38°C or <36°C, heart rate >90 beats per minute, respiratory rate >20 breaths per minute or PaCO2 <32 mmHg, and white blood cell count >12,000/mm³, <4,000/mm³, or >10% immature bands, with at least two of these criteria being present to indicate potential systemic inflammation that may lead to sepsis.
SIRS Criteria
The criteria for SIRS are as follows:
- Temperature of >38 °C or <36 °C
- Heart rate of >90 beats per minute
- Respiratory rate of >20 breaths per minute or partial pressure of CO2 of <32 mmHg
- White blood cell count of >12,000 per ml or <4,000 per ml, or >10% immature (band) forms These criteria are used to identify patients with potential systemic inflammation that may lead to sepsis, as described in the study by 1.
Clinical Application
When a patient meets two or more of these criteria along with a suspected or confirmed infection, they should be evaluated for sepsis, as noted in the guidelines by 1.
Limitations and Considerations
While SIRS criteria remain useful for initial screening, they lack specificity since many non-infectious conditions can trigger SIRS, which is why clinical judgment remains essential when interpreting these findings, as discussed in the study by 1. Newer tools like qSOFA (quick Sequential Organ Failure Assessment) and the Sepsis-3 definition are now preferred for sepsis identification as they better predict outcomes, as mentioned in the guidelines by 1.
Clinical Judgment
Clinical judgment is crucial in interpreting SIRS criteria, as many non-infectious conditions can trigger SIRS, and the presence of systemic inflammatory response syndrome (SIRS) is not exclusive to infection, as noted in the study by 1.
Recent Guidelines
The most recent guidelines, such as those published in 2024 by 1, continue to support the use of SIRS criteria for identifying potential systemic inflammation, while also acknowledging the importance of clinical judgment and the limitations of these criteria.
From the Research
Systemic Inflammatory Response Syndrome (SIRS) Criteria
The SIRS criteria are defined as the presence of two or more of the following conditions:
- Temperature greater than 38°C or less than 36°C 2, 3, 4, 5
- Heart rate greater than 90 beats per minute 2, 3, 4, 5
- Respiratory rate greater than 20 breaths per minute 2, 3, 4, 5
- White blood cell count greater than 12,000/mm3 or less than 4,000/mm3 2, 3, 4, 5
SIRS Criteria in Different Studies
The SIRS criteria have been used in various studies to predict outcomes in different medical conditions, including:
- Pressure sores 2
- Diabetic skin and soft tissue infections 3
- Intracerebral hemorrhage 4
- Subarachnoid hemorrhage 5
- Suspected infection in intensive care units 6
Key Findings
- The SIRS criteria are associated with poor outcomes in some medical conditions, such as subarachnoid hemorrhage 5 and intracerebral hemorrhage 4
- However, the SIRS criteria may not be predictive of outcomes in other conditions, such as diabetic skin and soft tissue infections 3
- The SOFA score has been shown to have greater prognostic accuracy for in-hospital mortality than SIRS criteria or qSOFA score in adults with suspected infection admitted to an ICU 6