What is Systemic Inflammatory Response Syndrome (SIRS)?

Instructor: Tara Schickel

Tara has taught staff nursing courses and has a master's degree in public health.

This lesson will define Systemic Inflammatory Response Syndrome (SIRS). The clinical signs of the syndrome and possible causes will be described. The need to recognize this syndrome will also be discovered.

Systemic Inflammatory Response Syndrome

Jane is a third year nursing student who is trying to learn about the body's immune system. Jane went to her clinical site today and cared for a patient who had an elevated temperature and an elevated heart rate. Jane assumed that he must have had an infection in his body, but was told that he did not. The nurse who was caring for the patient told Jane that he is exhibiting signs of Systemic Inflammatory Response Syndrome (SIRS).

Jane decided to go home and read more about this syndrome referred to as SIRS. Jane discovered that SIRS is the clinical signs of the body's immune system activating. Patients are considered to display SIRS criteria if they have any two or more of the following symptoms:

  • Temperature above 100.4F or below 96.8F
  • Heart rate above 90 beats per minute
  • Respiratory rate above 20 breaths per minute
  • Arterial Carbon Dioxide level (PaCO2) of less than 32
  • White Blood Cell count of more than 12,000 or less than 4,000

Could Be Infection, Maybe Not

Jane thinks about what she has read and remembers her patient. Her patient had a temperature of 101F and a heart rate of 98. However, the nurse said there was no infection present in the body. Jane is confused. It would seem that a patient who exhibited these symptoms would have an infection present.

Upon further reading, Jane discovers that SIRS is a common inflammatory response that could be caused by infection. However, infection is not the only cause of these symptoms. Some of the most common causes of SIRS are burns, trauma, cardiovascular disease, cardiac arrest, lung disease, and the body's peri-operative response, especially in cardiovascular surgeries. Jane reflects on her patient and realizes that he was admitted for an exacerbation of a chronic lung condition. As she thinks about these symptoms, she realizes the lung condition must be causing him to exhibit SIRS.

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