What is the efficacy of lactate levels as a predictor of sepsis (Systemic Inflammatory Response Syndrome)?

From the Guidelines

Lactate is a valuable predictor of sepsis severity and mortality, and its measurement should be prioritized in the initial assessment and ongoing management of septic patients. The most recent and highest quality study, published in 2017 in Critical Care Medicine 1, supports the use of lactate as a predictor of sepsis. Elevated lactate levels (>2 mmol/L) should prompt clinicians to consider sepsis, with levels >4 mmol/L indicating severe disease requiring immediate intervention.

Key Points

• Serial lactate measurements are particularly valuable, as failure to clear lactate (decrease by at least 10-20% within 2-6 hours) correlates with higher mortality.
• Lactate should be measured immediately when sepsis is suspected and repeated every 2-6 hours to monitor treatment response.
• The Surviving Sepsis Campaign recommends lactate measurement within one hour of sepsis recognition.
• Lactate elevation in sepsis occurs due to tissue hypoperfusion, increased glycolysis from stress response, and decreased lactate clearance from organ dysfunction.

Clinical Considerations

• While lactate is valuable, it must be interpreted alongside other clinical parameters including vital signs, organ function markers, and clinical presentation.
• False elevations can occur with seizures, strenuous exercise, liver dysfunction, and certain medications, so clinical context remains essential for proper interpretation.
• A significant reduction in mortality was seen in lactate-guided resuscitation compared to resuscitation without lactate monitoring, as reported in a meta-analysis of five randomized controlled trials (647 patients) 1.
• The use of lactate as a predictor of sepsis is supported by multiple studies, including those published in Intensive Care Medicine 1 and Critical Care Medicine 1.

Recommendation

Lactate measurement should be a priority in the initial assessment and ongoing management of septic patients, and its results should be used to guide resuscitation efforts. This approach is supported by the Surviving Sepsis Campaign and is consistent with the principles of evidence-based medicine. By prioritizing lactate measurement and using its results to guide treatment, clinicians can improve outcomes for patients with sepsis.

From the Research

Efficacy of Lactate Levels as a Predictor of Sepsis

• Lactate levels have been shown to be a useful predictor of sepsis, with elevated levels associated with poor outcomes 2, 3, 4, 5, 6.
• A study published in 2018 found that lactate levels at 6 hours after septic shock recognition were associated with 28-day mortality, with a higher prognostic value than lactate clearance 2.
• Another study published in 2014 found that bedside lactate levels were associated with sepsis severity, ICU admission, and need for vasopressors 3.
• A systematic review published in 2020 found that early lactate area scores and serial blood lactate levels were prognostic markers for patients with septic shock 4.
• A retrospective cohort study published in 2021 found that 6-hour lactate levels had better prognostic value than 6-hour lactate clearance in predicting 30-day mortality in patients with sepsis and septic shock 6.

Diagnostic Characteristics of Lactate Levels

• The diagnostic characteristics of lactate levels in combination with a clinical screening tool were found to have moderate to good specificity but low sensitivity in adult ED patients with suspected sepsis 3.
• The sensitivity and specificity of lactate levels in predicting sepsis and septic shock have been found to vary depending on the cut-off value used, with a cut-off value of ≥2 mmol/L having the highest sensitivity 2, 6.

Prognostic Value of Lactate Levels

• Lactate levels have been found to be a useful prognostic marker for patients with sepsis and septic shock, with elevated levels associated with increased mortality 2, 4, 6.
• The prognostic value of lactate levels has been found to be independent of other factors, such as age and comorbidities 2, 6.
• Lactate clearance has also been found to be a useful prognostic marker, with lower clearance rates associated with increased mortality 2, 6.