Diagnostic markers of sepsis in the emergency department

Sepsis is defined as the systemic inflammatory response to infection. However, changes in body temperature, heart and respiratory rate and white cell count (the SIRS criteria) are not specific enough to identify infected patients in the emergency department. Among many biological parameters, measurement of lactate, central venous oxygen saturation (ScvO2), C-reactive protein (CRP) and procalcitonin (PCT) are of particular interest. Early (within 6h) and goal-directed (ScvO2 > 70%) resuscitation increases survival in severe sepsis and septic shock, particularly in patients with high lactate clearances. CRP and PCT are both useful markers of sepsis but PCT increases earlier, better differentiates infective from non-infective causes of inflammation, more closely correlates with sepsis severity in terms of shock and organ dysfunction and better predicts outcome when followed in time. However, PCT measurement is more costly, time-consuming, and not widespread available. New markers for rapid diagnosis of sepsis (e.g. TREM-1) are under investigation.