Background: The triage nurse is involved in the early identification of the most severe patients at emergency department (ED) presentation. However, clinical criteria alone may be insufficient to identify them correctly. Measurement of capillary lactate concentration at ED presentation may help to discriminate these patients. The primary objective of this study was to identify the prognostic value of capillary lactate concentration measured by the triage nurse among patients presenting to the ED.

Methods: This was a prospective observational study, performed in the ED of a university hospital. At ED presentation, capillary lactate measurement was performed by the triage nurse among patients presenting with a clinical criteria of systemic inflammatory response syndrome (SIRS). Clinical variables usually used to determine severity were collected at presentation. Twenty-eight-day mortality and MEDS score were recorded.

Results: One hundred seventy-six patients with clinical SIRS presented to the ED. Median age was 72 years, and 28-day mortality was 16%. Capillary lactate at ED presentation was significantly higher among 28-day non-survivors than among survivors (5.7 mmol.L(-1) [3.2 to 7.4] vs 2.9 mmol.L(-1) [1.9 to 5.2], p = 0.003). A score based on mottling and capillary lactate concentration >3.6 mmol.L(-1) was significantly associated with 28-day mortality (area under curve, AUC = 0.75), independently of the MEDS score (AUC = 0.79) for the prediction of 28-day mortality (AUC global model 0.87).

Conclusions: A high capillary lactate concentration measured by the triage nurse among patients presenting to the ED with clinical SIRS is associated with a high risk of death. A score calculated by the triage nurse, based on mottling and capillary lactate concentration, appears to be useful for identifying the most severe patients.