A recent study has suggested that infectious states, which are extremely heterogeneous and rapidly evolving clinical conditions, are responsible for about one-fifth of daily admissions to Western emergency departments (EDs).1 Of these, a minor but not insignificant proportion of patients (between 15% and 20%) present a clear organic alteration from the very beginning, allowing the infectious state to be immediately classified as a septic condition responsible for 30% of in-hospital deaths.1, 2, 3 Considering patients with suspected infection in the ED, previous studies have reported an in-hospital mortality rate of 4.5% and an intensive care unit admission rate of 8.1%. These figures demonstrate the relevance and severity of this patient category.4

The prognostic assessment of an infectious state remains a clinical challenge.1,5 While only a small percentage of infectious states present in the ED with a clear state of hemodynamic instability or clear signs of organ dysfunction, a significant proportion of patients may seem stable at the first clinical evaluation, while they could have underlying organ damage and initial tissue dysfunction. If not promptly identified, such conditions may evolve into severe septic states with unfavourable prognoses.1,3,5 Therefore, the early identification of potential infectious states that may rapidly develop into multi-systemic conditions is crucial for improving short- to medium-term outcomes in these complex patients.6,7 However, the currently available clinical tools such as blood samples, prognostic scores, and instrumental examinations seem unable to adequately predict infectious states. Moreover, there are no markers that can identify early microvascular alterations underlying septic processes.6,7

A recent study showed that assessing estimated plasma volume status (ePVS) in patients evaluated in the ED for fever may provide a good indication of both the severity of the febrile process and the 30-day prognosis.8 Although there is no conclusive evidence, ePVS, derived simply from haemoglobin and haematocrit values, seems to be an early, rapid and reproducible prognostic tool in conditions where blood volume plays a key pathophysiological role, such as acute heart failure and septic states.8, 9, 10

For this reason, the ePVS upon arrival in the ED could help identify the most severe and critical patients within this heterogeneous category. It could distinguish patients with a serious underlying infection among apparently stable subjects.8 ePVS could, therefore, appear as a marker of mortality risk in patients with infection.

For these reasons, this study aimed to investigate the ability of ePVS in predicting 30-day mortality in ED patients with infections.