Systemic inflammatory response syndrome

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Systemic inflammatory response syndrome
ComplicationsAcute kidney injury, shock, septic shock, sepsis, multiple organ failure

In immunology, systemic inflammatory response syndrome (SIRS) is an inflammatory state affecting the whole body.[1] It is the body's response to an infectious or noninfectious insult. Although the definition of SIRS refers to it as an "inflammatory" response, it actually has pro- and anti-inflammatory components.



SIRS is frequently complicated by failure of one or more organs or organ systems.[2][3][4] The complications of SIRS include


The causes of SIRS are broadly classified as infectious or noninfectious. Causes of SIRS include:[citation needed]

Other causes include:[2][3][4]


Systemic inflammatory response syndrome[5]
Finding Value
Temperature <36 °C (96.8 °F) or >38 °C (100.4 °F)
Heart rate >90/min
Respiratory rate >20/min or PaCO2<32 mmHg (4.3 kPa)
WBC <4x109/L (<4000/mm3), >12x109/L (>12,000/mm3), or ≥10% bands

SIRS is a serious condition related to systemic inflammation, organ dysfunction, and organ failure. It is a subset of cytokine storm, in which there is abnormal regulation of various cytokines.[6] SIRS is also closely related to sepsis, in which patients satisfy criteria for SIRS and have a suspected or proven infection.[2][3][4][7]

Many experts consider the current criteria for a SIRS diagnosis to be overly sensitive, as nearly all (>90%) of patients admitted to the ICU meet the SIRS criteria.[8]


Manifestations of SIRS include, but are not limited to:[9]

When two or more of these criteria are met with or without evidence of infection, patients may be diagnosed with "SIRS". Patients with SIRS and acute organ dysfunction may be termed "severe SIRS".[3][4][10] Note: Fever and an increased white blood cell count are features of the acute-phase reaction, while an increased heart rate is often the initial sign of hemodynamic compromise. An increased rate of breathing may be related to the increased metabolic stress due to infection and inflammation, but may also be an ominous sign of inadequate perfusion resulting in the onset of anaerobic cellular metabolism.[citation needed]


The International Pediatric Sepsis Consensus has proposed some changes to adapt these criteria to the pediatric population.[11]

In children, the SIRS criteria are modified in the following fashion:[11]

Temperature or white blood cell count must be abnormal to qualify as SIRS in pediatric patients.[11]


Generally, the treatment for SIRS is directed towards the underlying problem or inciting cause (i.e. adequate fluid replacement for hypovolemia, IVF/NPO for pancreatitis, epinephrine/steroids/diphenhydramine for anaphylaxis).[12] Selenium, glutamine, and eicosapentaenoic acid have shown effectiveness in improving symptoms in clinical trials.[13][14] Other antioxidants such as vitamin E may be helpful as well.[15]

Septic treatment protocol and diagnostic tools have been created due to the potentially severe outcome septic shock. For example, the SIRS criteria were created as mentioned above to be extremely sensitive in suggesting which patients may have sepsis. However, these rules lack specificity, i.e. not a true diagnosis of the condition, but rather a suggestion to take necessary precautions. The SIRS criteria are guidelines set in place to ensure septic patients receive care as early as possible.[5]

In cases caused by an implanted mesh, removal (explantation) of the polypropylene surgical mesh implant may be indicated.[16]


The concept of SIRS was first conceived of and presented by William R. Nelson, of the Department of Surgery of the University of Toronto. SIRS was more broadly adopted in 1991 at the American College of Chest Physicians/Society of Critical Care Medicine Consensus Conference with the goal of aiding in the early detection of sepsis.[17]

Criteria for SIRS were established in 1992 as part of the American College of Chest Physicians/Society of Critical Care Medicine Consensus Conference.[2] The conference concluded that the manifestations of SIRS include, but are not limited to the first four described above under adult SIRS criteria.[citation needed]

In septic patients, these clinical signs can also be seen in other proinflammatory conditions, such as trauma, burns, pancreatitis, etc. A follow-up conference, therefore, decided to define the patients with a documented or highly suspicious infection that results in a systemic inflammatory response as having sepsis.[18] Note that SIRS criteria are non-specific,[18] and must be interpreted carefully within the clinical context. These criteria exist primarily for the purpose of more objectively classifying critically ill patients so that future clinical studies may be more rigorous and more easily reproducible.[citation needed]


  1. ^ Jaffer U, Wade RG, Gourlay T (2010). "Cytokines in the systemic inflammatory response syndrome: a review". HSR Proc Intensive Care Cardiovasc Anesth. 2 (3): 161–75. ISSN 2037-0504. PMC 3484588. PMID 23441054.
  2. ^ a b c d "American College of Chest Physicians/Society of Critical Care Medicine Consensus Conference: definitions for sepsis and organ failure and guidelines for the use of innovative therapies in sepsis" (PDF). Crit. Care Med. 20 (6): 864–74. 1992. doi:10.1097/00003246-199206000-00025. PMID 1597042. S2CID 20057097. Archived from the original (PDF) on 2013-10-17.
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  4. ^ a b c d Marino PL (1998). The ICU book. Baltimore: Williams & Wilkins. ISBN 0-683-05565-8.
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  6. ^ Parsons M (2010). "Cytokine storm in the pediatric oncology patient" (PDF). J Pediatr Oncol Nurs. 27 (5): 253–8. doi:10.1177/1043454210368533. PMID 20736486.
  7. ^ Kalil A (2020-10-07). "Septic Shock". Medscape.updated
  8. ^ Lord JM, Midwinter MJ, Chen YF, Belli A, Brohi K, Kovacs EJ, Koenderman L, Kubes P, Lilford RJ (October 2014). "The systemic immune response to trauma: an overview of pathophysiology and treatment". Lancet. 384 (9952): 1455–65. doi:10.1016/S0140-6736(14)60687-5. PMC 4729362. PMID 25390327.
  9. ^ Comstedt P, Storgaard M, Lassen AT (December 2009). "The Systemic Inflammatory Response Syndrome (SIRS) in acutely hospitalised medical patients: a cohort study". Scand J Trauma Resusc Emerg Med. 17: 67. doi:10.1186/1757-7241-17-67. PMC 2806258. PMID 20035633.
  10. ^ Tsiotou AG, Sakorafas GH, Anagnostopoulos G, Bramis J (March 2005). "Septic shock; current pathogenetic concepts from a clinical perspective". Med Sci Monit. 11 (3): RA76–85. PMID 15735579.
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  12. ^ Boka K (2019-06-26). "Systemic Inflammatory Response Syndrome Treatment & Management". Medscape.
  13. ^ Berger MM, Chioléro RL (September 2007). "Antioxidant supplementation in sepsis and systemic inflammatory response syndrome". Crit Care Med. 35 (9 Suppl): S584–90. doi:10.1097/01.CCM.0000279189.81529.C4. PMID 17713413. S2CID 21329654.
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  15. ^ Bulger EM, Maier RV (February 2003). "An argument for Vitamin E supplementation in the management of systemic inflammatory response syndrome". Shock. 19 (2): 99–103. doi:10.1097/00024382-200302000-00001. PMID 12578114. S2CID 35863434.
  16. ^ Voyles CR, Richardson JD, Bland KI, Tobin GR, Flint LM, Polk HC (August 1981). "Emergency abdominal wall reconstruction with polypropylene mesh: short-term benefits versus long-term complications". Ann Surg. 194 (2): 219–23. doi:10.1097/00000658-198108000-00017. PMC 1345243. PMID 6455099.
  17. ^ "CHEST Home".
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