• Presence of an infection with an associated systemic inflammatory response
  • The systemic inflammatory response syndrome (SIRS) is composed of 4 criteria:
    • Temperature >38°C or <36°C
    • Heart rate >90 bpm
    • Respiratory rate >20/min or PaCO2 <32 mm Hg
    • WBC >12,000/mm3, <4,000/mm3, or >10% bands
  • Sepsis = suspected infection with ≥2 SIRS criteria:
    • Release of chemical messengers by the inflammatory response
    • Macrocirculatory failure through decreased cardiac output or decreased perfusion pressure
    • Microcirculatory failure through impaired vascular autoregulatory mechanisms and functional shunting of oxygen
    • Cytopathic hypoxia and mitochondrial dysfunction
  • Hemodynamic changes result from the inflammatory response:
    • Elevated cardiac output in response to vasodilatation
    • Later myocardial depression
  • Multiple organ dysfunction syndrome (MODS):
    • Acute respiratory distress syndrome (ARDS)
    • Acute tubular necrosis and kidney failure
    • Hepatic injury and failure
    • Disseminated intravascular coagulation
  • Sepsis should be viewed as a continuum of severity from a proinflammatory response to organ dysfunction and tissue hypoperfusion:
    • Severe sepsis: Sepsis with at least 1 of the following organ dysfunctions:
      • Acidosis
      • Renal dysfunction
      • Acute change in mental status
      • Pulmonary dysfunction
      • Hypotension
      • Thrombocytopenia or coagulopathy
      • Liver dysfunction
    • Septic shock: Sepsis-induced hypotension despite fluid resuscitation:
      • Systolic BP <90 mm Hg or reduction of >40 mm Hg from baseline
  • Sepsis is the tenth leading cause of death in the U.S.:
    • In-hospital mortality for septic shock is ∼20%


  • Gram-negative bacteria most common:
    • Escherichia coli
    • Pseudomonas aeruginosa
    • Rickettsiae
    • Legionella spp.
  • Gram-positive bacteria:
    • Enterococcus spp.
    • Staphylococcus aureus
    • Streptococcus pneumoniae
  • Fungi (Candida species)
  • Viruses

Pediatric Considerations
  • Children with a minor infection may have many of the findings of SIRS
  • Major causes of pediatric bacterial sepsis:
    • Neisseria meningitidis
    • Streptococcal pneumonia
    • Haemophilus influenzae

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