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You are called to the emergency department to see a 67-year-old male for a suspected diverticular abscess. The EM resident tells you that “he’s starting to look sick” and you go immediately to see him. Vitals reveal a temperature of 102.7°F (39.3°C), pulse 102, blood pressure 90/50, a respiratory rate of 22, and an oxygen saturation of 96%. Physical exam reveals a somnolent male who grimaces when you palpate his abdomen. The nurse reports a clear mental status 1 hour prior. Stat labs reveal normal electrolytes and a leukocytosis of 17,000 WBC.


1. Does this patient meet the diagnostic criteria for systemic inflammatory response syndrome (SIRS)?


2. Does he meet the diagnostic criteria for sepsis?




Sepsis is a clinical syndrome characterized by a massive inflammatory response to infection. Over 650,000 cases of sepsis are diagnosed each year in the United States. Mortality is high and estimates range from 20% to 50% with rates increasing proportional to the severity of sepsis. Sepsis is thought to result from an overreaction of the immune response—a massive and uncontrolled release of proinflammatory mediators that leads to cardiovascular collapse and tissue injury. In its most severe form, sepsis can lead to multiorgan dysfunction syndrome (MODS) and subsequent death.


As sepsis is a clinical entity with a full spectrum of stages, much work has been done to codify and define its features.


  1. SIRS is the clinical syndrome that results from a dysregulated inflammatory response to an insult. It is nonspecific and can be caused by ischemia, inflammation, trauma, infection, or a combination of several insults.

    This patient has SIRS. To establish the diagnosis of SIRS, 2 of the following criteria must be met:

    • High or low WBC (>12,000 cells/mm3, <4000 cells/mm3, or >10% bands)
    • High or low temperature (>38.5°C or <35°C)
    • Heart rate >90
    • Respiratory rate >20 (or Paco2 <32 mm Hg)

  2. Sepsis is the clinical syndrome that results from the body’s abnormal inflammatory reaction to infection. Very simply:

    Sepsis = SIRS + documented infection

    This patient, in the absence of a documented infection, does not therefore have sepsis. Keep in mind that sepsis and bacteremia (bacteria in the bloodstream) are 2 different things. Patients can be bacteremic without being septic if they don’t meet diagnostic criteria for SIRS.

  3. Severe sepsis is defined by sepsis plus organ dysfunction (see Figure 8-1). This can be:

    • Areas of mottled skin
    • Capillary refill ≥3 seconds
    • UOP <0.5 mL/kg for at least 1 hour
    • Lactate >2 mmol/L
    • Change in mental status
    • Platelet count of <100,000 cells/mL or DIC
    • Acute lung injury/ARDS

  4. Septic shock is severe sepsis plus hypotension, which can include the following (see Figure 8-1):

    • MAP <60 mm Hg after fluid resuscitation
    • Pulmonary capillary wedge pressure between 12 and 20 mm Hg and need for vasopressors

  5. From the above definitions, for a patient to have sepsis there must be a source for the infection. This source can ...

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