Systemic inflammatory response syndrome

Systemic Inflammatory Response Syndrome (SIRS) is a condition that arises as a response to severe clinical insults. This syndrome is characterized by changes in temperature, heart rate, respiration rate, and blood cell count.

Definition

The American College of Chest Physicians and the Society of Critical Care Medicine introduced the concept of SIRS in 1992. According to their definition, SIRS is identified when two or more of the following conditions are present:

• Body temperature greater than 38°C or less than 36°C
• Heart rate greater than 90 beats per minute
• Respiratory rate greater than 20 breaths per minute or PaCO2 less than 32 mm Hg
• White blood cell count greater than 12,000/mm³, less than 4,000/mm³, or greater than 10% immature (band) forms

Causes

SIRS can be caused by a variety of conditions, including infection, trauma, ischemia, inflammation, and sepsis. It is important to note that SIRS can occur without the presence of infection, particularly in cases of severe trauma or inflammation.

Pathophysiology

The pathophysiology of SIRS involves a complex interaction between the immune system, coagulation system, and vascular system. The body's response to a severe insult involves the release of pro-inflammatory and anti-inflammatory mediators, leading to systemic inflammation. This can result in changes to the vascular system, including increased vascular permeability and vasodilation, which can lead to shock.

Treatment

Treatment of SIRS is primarily supportive and depends on the underlying cause. This may include antibiotics for infection, fluid resuscitation for shock, and mechanical ventilation for respiratory failure. Early recognition and treatment of SIRS is crucial to prevent progression to severe sepsis and septic shock.

See also

• Sepsis
• Septic shock
• Multiple organ dysfunction syndrome