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What is severe sepsis and septic shock ?

Severe sepsis refers to sepsis-induced tissue hypoperfusion or organ dysfunction with any of the following thought to be due to the infection.
  • Sepsis-induced hypotension
  • Serum Lactate levels above upper limits of laboratory normal
  • Urine output < 0.5 mL/kg/hr for more than two hours inspite of adequate fluid resuscitation
  • Acute lung injury with PaO 2 /FIO 2 < 250 in the absence of pneumonia as infection source
  • Acute lung injury with PaO 2 /FIO 2 < 200 in the presence of pneumonia as infection source
  • Creatinine > 2 mg/dL 
  • Bilirubin > 2 mg/dL 
  • Platelet count < 100,000 microL –1
  • Coagulopathy (INR > 1.5)
Sepsis-induced hypotension is defined as a systolic blood pressure (SBP) < 90 mmHg or mean arterial pressure (MAP) < 70 mmHg or a SBP decrease > 40 mmHg or less than two standard deviations below normal for age in the absence of other causes of hypotension.

Components of Sepsis-induced tissue hypoperfusion are

  1. Infection-induced hypotension
  2. Elevated lactate
  3. Oliguria.  
Septic shock Septic shock is defined as sepsis-induced hypotension persisting despite adequate fluid resuscitation, which may be defined as infusion of 30 mL/kg of crystalloids Septic shock is due to marked reduction in systemic vascular resistance, this is often associated with an increase in cardiac output.