Systemic Inflammatory Response Syndrome

Pathophysiology

Proinflammatory cytokines (IL-1, IL-6, TNF-α) are released in response to tissue injury or infection, leading to an upregulated innate immune response in patients with systemic inflammatory response syndrome 1
Activation of neutrophils, macrophages, and natural killer cells leads to an upregulated innate immune response in patients with systemic inflammatory response syndrome 2
Metabolic, neuroendocrine, hematologic, and hepatic changes occur in patients with systemic inflammatory response syndrome, including loss of muscle mass, increased lipolysis, and production of acute phase proteins (e.g., C-reactive protein) 1, 2

Surgical trauma and cardiopulmonary bypass during cardiac surgery can lead to the release of stress hormones and inflammatory mediators in patients undergoing surgery 1, 3
Bacterial, viral, fungal, and parasitic infections, as well as tissue injury from surgery, trauma, hematoma, venous thrombosis, myocardial or pulmonary infarction, and burns can lead to SIRS 4

The presence of SIRS criteria helps identify patients at risk for poor outcomes, with criteria including:

C-reactive protein (CRP) is a valuable marker for quantifying the magnitude of the postoperative systemic inflammatory response in patients undergoing surgery 1
CT scan and MRI are diagnostic tests with high sensitivity and specificity for diagnosing conditions associated with SIRS, such as splenic infarction 7

Minimizing surgical trauma, appropriate perioperative nutrition, and maintaining near-zero fluid balance during major procedures can help reduce the risk of SIRS 3, 1
The American College of Critical Care Medicine recommends tracking vital signs and laboratory markers, including WBC count, lactate, and organ function tests, for patients with SIRS 8
Administering empiric broad-spectrum antibiotics, beginning fluid resuscitation, and identifying and controlling the source of infection are recommended treatments for patients with SIRS 9
Monitoring vital signs and organ function regularly, reassessing response to treatment, and adjusting antibiotics based on culture results are essential for managing patients with SIRS 9
Consider specialized care for patients with SIRS associated with liver disease, including avoidance of nephrotoxins and early treatment with intravenous albumin and vasoconstrictors for hepatorenal syndrome, as recommended by the American Association for the Study of Liver Diseases 8

Age, malnutrition, diabetes, smoking, obesity, prolonged hospitalization, shock, hypoxemia, and hypothermia increase the risk of developing SIRS 4, 10
Mortality risk increases with the number of SIRS criteria present and with progression to organ dysfunction 9, 1
SIRS represents a dysregulated host response, and its progression can lead to severe conditions such as severe sepsis, septic shock, Multiple Organ Dysfunction Syndrome (MODS), Acute Respiratory Distress Syndrome (ARDS), and Disseminated Intravascular Coagulation (DIC) 5