What is NOT included in the criteria for Systemic Inflammatory Response Syndrome (SIRS)?

The criteria for Systemic Inflammatory Response Syndrome (SIRS) are established to help identify patients who are experiencing a severe inflammatory response, often due to infection or trauma. The condition is characterized by a combination of clinical findings that reflect a systemic response to inflammation.

Among the criteria, a heart rate greater than 90 beats per minute indicates tachycardia, which is a common physiological response to stress or inflammation. A body temperature that is less than 36°C or greater than 38°C indicates a dysregulated thermal response, linking to fever or hypothermia, both of which can occur in inflammatory situations. A respiratory rate greater than 20 breaths per minute or a partial pressure of carbon dioxide (PaCO2) less than 32 mmHg reflects hypoventilation or respiratory compensation, signaling that the body is responding to acid-base imbalances typically seen in states of stress.

In contrast, a white blood cell count less than 4,000 cells/mm³ is not included in SIRS criteria. In fact, an elevated white blood cell count (leukocytosis) is typically considered indicative of systemic inflammatory responses or infections. A low count suggests a lack of inflammatory response, which does not align with the definition of SIRS