Objective: In intensive care settings, blood lactate level measurement proved to be an excellent predictor of outcomes. In patients requiring less urgent treatment, the arterial blood lactate is less sensitive and its usefulness remains to be proven. Capillary blood lactate dosing, an emergent point-of-care technique readily available should be more sensitive to changes in these settings.

Method: prospective, observational, monocentric study conducted in a polyvalent internal medicine ward in a French University Hospital. The inclusion criteria were the existence of new symptoms of abrupt onset in an otherwise stable patient. All the patients had a point of care measurement of baseline capillary and venous lactate levels (EDGE, ApexBio) and standardized control before any therapeutic means were initiated. A follow-up test was performed once again within 12 to 36 hours. All the patients received standard medical care adapted to their condition. The primary outcomes were considered dying within 30 days or requiring intensive care or invasive therapeutic procedures.

Results: 13 patients were analyzed. Seven patients reached the composite outcome with 3 deaths. The superimposed complication proved to be infectious in every case. The median lactate levels were at baseline (mmol/ l): capillary Mc0=5.2(2.16), venous Mv0=2.3(2.0) and arterial Ma0=1.8(1.7) and at follow-up (mmol/ l) capillary: Mc1=3.3(1.1), venous Mv1=1.8(1.8) and arterial Ma1=1.3(0.7).

In nonparametric analysis, the absence of normalization of capillary lactate at follow-up was correlated well with poor outcomes (p=.05). This was not the case of arterial or venous lactate measurements. The positive lactate clearance was present in the majority of patients (83.3%) but it did not predict the outcomes (p=.435) and there was no correlation between the baseline lactate and the clinical outcome (p>.05).

Conclusion: In non intensive care settings, capillary lactate level could be a more sensitive method than the classical lactate measurement for predicting the outcomes of acute conditions, especially infectious. A persistently high lactate level rather than its initial value or clearance seems to correlate better with poorer outcomes.

Abbreviations: SSC = Surviving sepsis campaign, ED = Emergency department, ICU = intensive care unit, , POC = Point of care, ICC = inter class coefficient