What is systemic inflammatory response syndrome (SIRS)?

Systemic inflammatory response syndrome (SIRS)

SIRS is defined as a systemic response to a non-specific infectious or non-infectious insults such as from burns, pancreatitis, an autoimmune disorder, ischemia, or trauma. 

The presence of two or more of the following clinical criteria help establish the diagnosis of SIRS: 

  • Body temperature higher than 38°C (100.4°F) or lower than 36°C (96.8°F) 
  • Heart rate faster than 90 beats per minute
  • Respiratory rate more than 20 breaths per minute or hyperventilation with an arterial carbon dioxide tension (PaCo2) less than 32 mm Hg
  • Abnormal white blood cell count (greater than 12,000/ mcL or less than 4000/mcL or greater than 10% immature [band] forms)

N.B: When a source of infection is confirmed, SIRS is categorized as sepsis

general features and causes of inflammation


  • CURRENT Medical Diagnosis & Treatment 2018; page 502
  • Robbins Basic Pathology 10th Edition; page: 58 (Fig 3.1) & 60 

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