Relative Hyperlactatemia in the Emergency Department

Area of Science:

• Emergency Medicine
• Clinical Chemistry
• Critical Care

Background:

• The interpretation of lactate levels within the normal range in emergency department (ED) patients requires further clarification.
• Lactate is a key biomarker for assessing tissue hypoperfusion and cellular metabolism.

Purpose of the Study:

• To determine the optimal lactate cutoff value within the reference range (<2.00 mmol/L) for predicting in-hospital mortality in ED patients.
• To investigate the association between relative hyperlactatemia and mortality in this population.

Main Methods:

• Retrospective analysis of adult patients presenting to a tertiary ED with initial serum lactate <2.00 mmol/L.
• Utilized Youden's index to identify the optimal lactate threshold for mortality prediction.
• Assessed in-hospital mortality as the primary outcome.

Main Results:

• A lactate cutoff of 1.33 mmol/L was identified as optimal for discriminating between survivors and non-survivors.
• Relative hyperlactatemia (lactate > 1.33 mmol/L) was an independent predictor of in-hospital mortality (OR 1.78).
• This association was more pronounced in patients without comorbidities like hypertension, diabetes, or COPD.

Conclusions:

• The optimal initial serum lactate cutoff for predicting mortality in ED patients is 1.33 mmol/L.
• Relative hyperlactatemia is a significant predictor of increased mortality in ED patients.
• The prognostic value of relative hyperlactatemia is particularly relevant in patients without significant comorbidities.