What is the clinical utility of lactic acid (lactate) testing?

From the Guidelines

Lactic acid testing is a crucial tool in clinical practice, particularly in critically ill patients, as it provides a more objective surrogate for tissue perfusion and has been shown to reduce mortality when used to guide resuscitation efforts in septic shock patients. The clinical utility of lactic acid testing is well-established, with evidence from five randomized controlled trials (647 patients) demonstrating a significant reduction in mortality when lactate-guided resuscitation is compared to resuscitation without lactate monitoring (RR 0.67; 95% CI 0.53–0.84; low quality) 1. Key benefits of lactic acid testing include:

• Assessing tissue oxygenation and perfusion in critically ill patients
• Guiding resuscitation efforts in septic shock patients
• Evaluating treatment effectiveness through serial lactate measurements
• Providing a biomarker for tissue hypoxia, as lactic acid is produced during anaerobic metabolism when oxygen delivery to tissues is insufficient. The use of lactic acid testing is especially important in emergency settings, such as in patients with suspected sepsis, cardiac arrest, severe trauma, or shock, as elevated lactate levels in these conditions correlate with increased mortality 1. Overall, the evidence supports the use of lactic acid testing as a valuable tool in clinical practice, particularly in critically ill patients, to improve outcomes and reduce mortality.

From the Research

Clinical Utility of Lactic Acid (Lactate) Testing

• Lactate testing has been studied in various disease states, including sepsis and septic shock, and is associated with increased mortality 2.
• Elevations in blood lactate concentrations have been used as a prognostic indicator, and serial lactate levels have been suggested as a useful therapeutic target for resuscitation 2.
• Lactate measurements have gained a prominent role in sepsis definitions, screening protocols, management guidelines, and quality measures over the past two decades 2.

Diagnostic and Prognostic Uses of Lactate Monitoring

• Lactate monitoring has been used to diagnose and monitor sepsis, with elevated lactate levels associated with poor outcomes 3, 4.
• The diagnostic characteristics of a clinical screening tool in combination with measuring bedside lactate levels in emergency department patients with suspected sepsis have been evaluated, with moderate to good specificity but low sensitivity reported 4.
• Lactate levels have been associated with sepsis severity, ICU admission, and need for vasopressors 4.

Therapeutic Uses of Lactate Monitoring

• Lactate monitoring has been used to guide resuscitation strategies, with some studies suggesting that lactate clearance may be a useful therapeutic target 2.
• However, the use of lactate-guided therapy has been controversial, with some studies showing no benefit and potential harm 2.
• Therapy for lactic acidosis is designed to maximize oxygen delivery and reduce tissue hypoxia, with buffering agents not shown to materially affect outcome 5.

Lactate as a Biomarker

• Lactate levels are frequently elevated in critically ill patients and correlate well with disease severity 6.
• Elevated lactate levels are prognostic in prehospital, emergency department, and intensive care unit settings 6.
• Lactate has been discussed as a biomarker in diagnosing and assessing the severity of systemic hypoperfusion, as well as guiding clinical care and enabling prognosis in critically ill patients 6.