Systemic inflammatory response syndrome (SIRS) is an inflammatory state affecting the whole body. 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. Presentation Complications SIRS is frequently complicated by failure of one or more organs or organ systems. The complications of SIRS include Acute kidney injury Shock Multiple organ dysfunction syndrome Causes The causes of SIRS are broadly classified as infectious or noninfectious. Causes of SIRS include: bacterial infections severe malaria trauma burns pancreatitis ischemia hemorrhage Other causes include: Complications of surgery Adrenal insufficiency Pulmonary embolism Complicated aortic aneurysm Cardiac tamponade Anaphylaxis Drug overdose Diagnosis 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. SIRS is also closely related to sepsis, in which patients satisfy criteria for SIRS and have a suspected or proven infection. 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. Adult Manifestations of SIRS include, but are not limited to: Body temperature less than 36 °C (96.8 °F) or greater than 38 °C (100.4 °F) Heart rate greater than 90 beats per minute Tachypnea (high respiratory rate), with greater than 20 breaths per minute; or, an arterial partial pressure of carbon dioxide 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); or the presence of greater than 10% immature neutrophils (band forms). Band forms greater than 3% is called bandemia or a "left-shift". 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". 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. Children The International Pediatric Sepsis Consensus has