Diagnosis of Severe Sepsis and Septic Shock
(from the Surviving Sepsis Guidelines)
Sepsis is defined as an infection (definite or suspected) with systemic manifestations (any 2 from a list). This definition may seem overly broad -- it means that many people with colds and self-limited viral syndromes have sepsis -- but that's by design.
Sepsis can present in subtle and surprising ways, with minimal abnormalities in vital signs and laboratory testing. For this reason, sepsis often goes unrecognized in its earliest, most treatable phase. The criteria for definition of sepsis were chosen in order not to miss anyone with an impending severe illness -- in other words, to be sensitive, but not specific.
Severe sepsis results when sepsis progresses to include impaired blood flow to body tissues (hypoperfusion), or detectable organ dysfunction. This usually includes low blood pressure (hypotension), but severe sepsis can occur with a normal blood pressure (e.g., with patchy hypoperfusion to certain organs, or toxin-induced encephalopathy).
Septic shock is severe sepsis with systolic blood pressure < 90 mm Hg (or a drop of > 40 mm Hg from baseline) or mean arterial pressure < 70 mm Hg, that persists after adequate fluid resuscitation. "Adequate" might be 2 liters of crystalloid in the previously healthy, or 10 liters in someone severely dehydrated after days of illness.
When sepsis is present or suspected, the Surviving Sepsis Campaign's Surviving Sepsis Guidelines advise rapid action be taken to establish a sepsis diagnosis and to diagnose its cause.
Surviving Sepsis Guidelines: Initial Tests for Sepsis Diagnosis
For patients suspected to be in severe sepsis or septic shock, body fluid cultures should be obtained as quickly as is feasible. The Surviving Sepsis Campaign strongly recommends collecting at least 2 sets of aerobic and anaerobic blood cultures; these should be drawn before giving antibiotics -- as long as cultures can be collected without delaying antimicrobial therapy by >45 minutes.
At least one blood culture bottle set should be collected percutaneously (through a needle stick), and one drawn from each venous or arterial catheter (IVs, dialysis access, central line, surgical port, arterial line, etc). If a line or device has been placed in the last 48 hours, it can be considered non-infected and no culture drawn.
Other cultures (e.g., urine) should be collected, if clinically indicated, with the same imperative to avoid undue delay of antibiotics.
Strength: Grade 1C, strong recommendation based on low-quality evidence.
In the uncommon situation in which invasive candidiasis is being considered as a cause of sepsis, collect blood for the 1,3 beta-D-glucan assay, and/or the mannan and anti-mannan antibody assays, which can help diagnose invasive candida infections.
Strength: Grade 2B - 2C, weak recommendation based on evidence of low quality (for mannan/anti-mannan antibodies) and moderate quality (for 1,3 beta-D glucan).
The Surviving Sepsis Campaign also recommends that appropriate imaging studies be performed quickly, to help confirm potential sources of infection. Strength: not graded.
Guide to Recommendations’ Strengths and Supporting Evidence in the Surviving Sepsis Guidelines:
- 1 = strong recommendation;
- 2 = weak recommendation or suggestion;
- A = good evidence from randomized trials;
- B = moderate strength evidence from small randomized trial(s) or upgraded observational trials;
- C = low strength evidence, well-done observational trials with control randomized controlled trials
- D = very low strength evidence, downgraded controlled studies or expert opinion.
PulmCCM is not affiliated with the Surviving Sepsis Campaign or the Surviving Sepsis Guidelines.