systemic inflammatory response syndrome
ABBR: SIRS
Any severe illness characterized by a heart rate > 90 beats per min, respirations exceeding 20 breaths per minute, a PaCO 2 of less than 32 mm Hg, and a white blood count greater than 12,000 cells/mL or less than 4000 cells/mL (or the presence of more than 10% immature (band ) white blood cells). SIRS can begin with any serious illness or injury involving inflammation but is most often associated with systemic infection (sepsis) caused by gram-negative bacteria.
SEE: sepsis; septic shock .
Etiology: Lipopolysaccharide endotoxins released by gram-negative and gram-positive bacteria bind with lymphocytes and endothelial cells, stimulating a cascade of cytokine release, which produces systemic inflammation of blood vessels, tissues, and organs. Shock develops when cytokines cause vasodilation and increased vascular permeability; SIRS is one of the main causes of multiple organ dysfunction syndrome.
Treatment: Treatment for SIRS is focused on treating the primary cause. Multiple antibiotic therapy is required in sepsis. Supportive measures include the use of intravenous fluids and pressors, to support blood pressure, and intensive monitoring and optimization of oxygenation, ventilation, blood pressure, cardiac rhythms, serum electrolytes, and renal function.