Question 27 from the first paper of 2007 stumped the candidates by asking them why it might be difficult to make the clinical or laboratory diagnosis of sepsis in the critically ill patient. One might surmise that many of them have never experienced any difficulty in making that diagnosis. LITFL has an excellent page on this topic which is enough for most people. If one were in need of a literature reference, the one best article would probably be this 2006 Belgian paper by Vandijck Decruyenaere and Blot.
In brief, the aforementioned difficulties can be summarised thus:
- Old diagnostic SIRS/sepsis criteria were non-specific for infection
- New "Sepsis 3" criteria also have methodological flaws, eg. they rely on SOFA scoring
- Infectious and non-infectious causes of shock may coexist
- Source of infection is hard to find (no history in the comatose patient, clinical findings obscured by critical illness)
- There are no specific clinical signs in sepsis
- Critically ill malnourished elderly or immunocomromised patients do not manifest typical signs of sepsis
- The laboratory markers of sepsis are non-specific (eg. CRP, WCC, even procalcitonin)
- Serology, PCRs and cultures take many hours to process
- Antibiotics obscure culture results
- Imaging may be non-specific (eg. infected vs. sterile collection)
In other words, our definitions are crap, our tests suck, and our patients are too complex to be pidgeonholed into narrow diagnostic categories.
More detail and specific criticims of the disgnostic criteria can be found in these specific chapters:
The purpose of this chapter is to help candidates answer questions along the line of "discuss the difficulty in making the diagnosis of sepsis", which requires three major sections:
Why would these criteria be difficult to apply to the diagnosis of sepsis in the ICU?
To go through them systematically:
The savvy candidate will have ignored much of this, as it is a discussion of outdated parameters, a definition which has now been rendered obsolete.
Oh's Manual is listed as one of the references; however the sepsis chapter never answers this actual question, unhelpfully remarking that "the initial presentation of severe sepsis and septic shock is often non-specific and ‘cryptic’..."
Levy, Mitchell M., et al. "2001 sccm/esicm/accp/ats/sis international sepsis definitions conference." Intensive care medicine 29.4 (2003): 530-538.
Vandijck, D. M., J. M. Decruyenaere, and S. I. Blot. "The value of sepsis definitions in daily ICU-practice." Acta Clinica Belgica 61.5 (2006): 220-226.