From the Guidelines
The Systemic Inflammatory Response Syndrome (SIRS) criteria are defined by the presence of two or more of the following four criteria: 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, as stated in the most recent guideline 1.
SIRS Criteria
The SIRS criteria are clinical parameters used to identify patients with potential systemic inflammation that may indicate sepsis. These criteria help clinicians rapidly identify patients who may have an inflammatory response to infection or other insults like trauma, burns, or pancreatitis.
- Temperature >38°C or <36°C
- Heart rate >90 beats per minute
- Respiratory rate >20 breaths per minute or PaCO2 <32 mmHg
- White blood cell count >12,000/mm³, <4,000/mm³, or >10% immature bands It's essential to note that while SIRS criteria are sensitive, they lack specificity for sepsis, as many non-infectious conditions can trigger SIRS, as described in previous studies 1.
Clinical Application
When SIRS is present with a confirmed or suspected infection, this constitutes sepsis. Prompt recognition using these criteria allows for earlier intervention, which is crucial as delayed treatment of sepsis increases mortality. In clinical practice, these criteria should trigger further evaluation, including blood cultures, lactate measurement, and consideration of appropriate antimicrobial therapy if infection is suspected. The most recent guidelines support the use of these criteria for identifying SIRS and guiding further management 1.
From the Research
SIRS Criteria
- The Systemic Inflammatory Response Syndrome (SIRS) is a clinical expression of the action of complex intrinsic mediators of the acute phase reaction 2.
- SIRS can be precipitated by events such as infection, trauma, pancreatitis, and surgery 2, 3.
- The SIRS criteria include:
- Body temperature greater than 38°C or less than 36°C
- Heart rate greater than 90 beats per minute
- Tachypnea, with more than 20 breaths per minute, or hyperventilation, as evidenced by a PaCO2 less than 32 mmHg
- White blood cell count greater than 12,000 cells/mm^3, less than 4,000 cells/mm^3, or the presence of more than 10% immature neutrophils (bands)
- SIRS and Multiple Organ Dysfunction Syndrome (MODS) are graded expressions of the inflammation associated with acute illness 2.
SIRS and Vancomycin
- Patients with SIRS had a significantly higher vancomycin clearance than those without SIRS, indicating that SIRS patients had a higher elimination capacity 4.
- The vancomycin clearance was positively correlated with the SIRS score defined as the number of positive items in the criteria, and negatively with age, except in patients with renal dysfunction 4.
- An increased vancomycin dosage would be needed in patients with a higher SIRS score to maintain the therapeutic target concentration, in particular in those with a high creatinine clearance value 4.
- Vancomycin initial doses of ≥20 mg/kg led to faster resolution of SIRS although further studies are needed to evaluate the safety and efficacy of this approach 5.
SIRS Duration and Vancomycin Concentration
- The duration of SIRS influences serum vancomycin concentration in patients with sepsis 6.
- Shorter and longer SIRS duration were associated with vancomycin concentrations in the lower group and the upper group, respectively, compared with predicted values in patients with sepsis 6.
- SIRS duration was identified as influencing vancomycin concentration in patients with sepsis, and modifying vancomycin dosing according to SIRS duration will improve prediction accuracy of vancomycin concentration based on therapeutic drug monitoring 6.