Systemic Inflammatory Response Syndrome (SIRS) Calculator

How does this Systemic Inflammatory Response Syndrome (SIRS) calculator work?

This health tool aims to help clinicians in the diagnosis of SIRS in adult patients based on the readily available criteria.

The systemic inflammatory response syndrome represent the inflammatory state as response of the immune system to infection or other illness.

The clinical criteria in the Systemic Inflammatory Response Syndrome (SIRS) calculator are the following:

■ Body temperature less than 36°C (96.8°F) or greater than 38°C (100.4°F). Fever is characteristic to the acute phase reaction.

■ Heart rate greater than 90 beats per minute. Increased heart rate is suggestive of hemodynamic compromise.

■ Tachypnea defined as high respiratory rate with more than 20 breaths per minute either due to increased metabolic stress or inadequate perfusion.

■ Partial arterial pressure of CO₂ less than 4.3 kPa (32 mmHg).

■ White blood cell count less than 4000 cells/mm³ (4 x 10⁹ cells/L) or greater than 12,000 cells/mm³ (12 x 10⁹ cells/L) as sign of inflammation. These are signs of the acute phase reaction.

■ Presence of greater than 10% immature neutrophils (band forms).

■ Hyperglycemia (blood glucose >6.66 mmol/L [120 mg/dL]) in absence of diabetes mellitus.

■ Acutely altered mental state as evidenced during clinical examination.

The patient is positive for SIRS if at least two of the above criteria are met.

This was used between 1992 and 2016 as early detection of sepsis, however currently the criteria only helps SIRS diagnosis alongside clinical judgment because it is considered to be too sensitive and most ICU patients tend to meet it.

Another criticism received by these criteria is the fact that these are mainly unspecific and cannot offer full diagnosis or treatment recommendations.

In February 2016, these criteria have been declared as not recommended for future diagnosis of sepsis, because of a lack of sensitivity and specificity. qSOFA score comprises of the latest guidelines in early sepsis diagnosis and comes as a shortened version of the SOFA score applicable in ICU.

SIRS causes and complications

While the main classification is made between infectious and non infectious, there are also other complications leading to SIRS such as adrenal insufficiency, cardiac tamponade, pulmonary embolism or anaphylaxis.

Most frequent non infectious causes include trauma, pancreatitis, ischemia, burns and hemorrhage.

Infectious causes that lead to systemic inflammatory response syndrome are reunited under the term sepsis, meaning bacteremia within the bloodstream. Severe sepsis is accompanied by organ dysfunction, hypotension and hypoperfusion.

Left untreated SIRS leads to acute lung or kidney injury, acute respiratory distress syndrome (ARDS), shock and multiple organ dysfunction syndrome.

Complications vary depending on the underlying etiology but clinical prophylaxis is usually put in place against DVT, stress ulcer and different super infections.

References

1) Balk RA. (2014) Systemic inflammatory response syndrome (SIRS). Where did it come from and is it still relevant today? Virulence; 5(1): 20–26.

2) Bone RC, Balk RA, Cerra FB, Dellinger RP, Fein AM, Knaus WA, Schein RM, Sibbald WJ. (1992) Definitions for sepsis and organ failure and guidelines for the use of innovative therapies in sepsis. The ACCP/SCCM Consensus Conference Committee. American College of Chest Physicians/Society of Critical Care Medicine. Chest; 101(6):1644-55.

3) Kaukonen KM, Bailey M, Pilcher D, Cooper DJ, Bellomo R. (2015) Systemic inflammatory response syndrome criteria in defining severe sepsis. N Engl J Med; 372(17):1629-38.

4) Levy MM, Fink MP, Marshall JC, Abraham E, Angus D, Cook D, Cohen J, Opal SM, Vincent JL, Ramsay G. 2001 SCCM/ESICM/ACCP/ATS/SIS International Sepsis Definitions Conference. Crit Care Med; 31(4):1250-6.

5) Haeberle H, Körner A, Rosenberger P. (2015) Systemic Inflammatory Response Syndrome Criteria for Severe Sepsis. N Engl J Med; 373(9):880-1.