Sepsis

Basics

Description

  • Presence of an infection with an associated host response
  • The systemic inflammatory response syndrome (SIRS) is an older sepsis definition 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, <4000/mm3, or >10% bands
  • Sepsis = suspected infection plus host response:
    • 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 host 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 manifesting as:
    • 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 or vasopressor dependent to maintain a systolic BP <90 mm Hg
  • Sepsis is the 10th leading cause of death in US:
    • In-hospital mortality for septic shock is ∼20%

Etiology

  • 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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