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I don't understand Sepsis?

  1. May 20, 2014 #1
    Hello everyone,

    I don't understand sepsis. Ok I know Sepsis is SIRS (Systemic inflammatory response syndrome) to an infection. But I'm confused with these scenarios.

    1) Lets say I have a UTI in kidney. The immune system localises the infection to kidney and causes massive inflammation in that area and fights the disease, with out allowing it to spread to otherarea. Now is this Sepsis? If it is not what do you call it? Here also inflammation towards infection occurs so why is it not called sepsis? Does CRP increase in this scenario?

    2) Lets say I have a UTI in kidney. It spreads to all areas in body. Massive systemic inflammation occurs towards the infection. I'm assuming this is sepsis?, then what do you call scenario 1 I described. What happens to CRP in this condition.

    3) You want inflammation and immune response against infections to fight them. So why is sepsis bad?

    Thanks :smile:
  2. jcsd
  3. May 20, 2014 #2


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    Too much inflammatory response by the body can damage vital organs and cause death. That's why sepsis is bad. If a fever produces a body temp. > 106 F for extended periods, this can also cause damage to vital organs, including the brain. A little sepsis is OK, too much can be deadly.
  4. May 20, 2014 #3


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    Close. Sepsis is SIRS + a source infection. SIRS criteria are 2+ of the following:
    -temp >101 or <96.8
    -tachycardia >90 bpm
    -tachypnea >20
    -PCO2 <32
    -Hyperglycemia >120 (w/o DM)
    -WBC >12000 or <4000

    Thus SIRS is, itself nonspecific and can be caused by non-infectious pathology. When it is caused by infectious pathology and you have a source SIRS is sepsis. Vs consider, bacteremia which is just a +blood culture without necessarily meeting the conditions of SIRS.

    Further sepsis is divided into sepsis, severe sepsis and septic shock.

    Severe sepsis is defined by acute circulatory failure (SBP <90 or reduced >40 from baseline or lactate >2 which is evidence of severe hypoperfusion). Shock is when you meet the above and the patient fails to respond to adequate fluid resuscitation.

    Kind of on the end of the SIRS spectrum would be Multiple organ dysfunction syndrome where you have the above +evidence of >2 organ systems failing.

    You have a source, it depends on if you meet 2+ of the SIRS criteria listed above. If they don't have the criteria met above a "UTI in the kidney" would be called pyelonephritis.

    Same as above. If they meet 2+ SIRS criteria and you know the source (the kidney infection in this case) then you meet criteria for sepsis. If its a massive spread of the infection and they have end organ failure, it would likely be severe sepsis or MOD syndrome.

    On CRP: it is an acute phase reactant that becomes elevated with inflammation. When you have systemic inflammation it usually trends very high (>10).

    In a clinical setting sepsis indicates an infection that has grown beyond the body's control. Acutely a patient can rapidly progress to shock or MODS and it has a high mortality rate if left untreated.

    Yes you do want inflammation and a immune response locally, but this can get out of control. Local cytokines ideally activate an immune response to do with the insult. However, if that doesn't clear the infection, cytokines end up in the blood stream to try and improve the local response (growth factors, better white cell recruitment, B-cell activation etc). Normally the body decreases proinflammatory agents at this point and the infection gets resolved and homeostasis is restored. If it doesn't the immune response (cytokines, interluekins etc) can get "carried away" and you can have a runaway inflammatory response. This is dangerous to the patient and requires intervention normally for a patient to survive.
  5. May 25, 2014 #4
    Thanks :smile: I get it now
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