From the Guidelines
Lactic acid levels should be checked before administering a fluid bolus, not after, as this provides a baseline measurement of the patient's metabolic state and helps guide initial treatment decisions 1. When evaluating a patient for conditions like sepsis or shock, obtaining a baseline lactic acid measurement is crucial, as it can help identify tissue hypoperfusion and guide resuscitation efforts 1. The Surviving Sepsis Campaign guidelines suggest guiding resuscitation to normalize lactate in patients with elevated lactate levels as a marker of tissue hypoperfusion, although this is a weak recommendation with low quality of evidence 1.
In clinical practice, checking lactic acid levels before administering a fluid bolus allows for a more accurate assessment of the patient's response to treatment, as the bolus itself can temporarily alter lactic acid levels, potentially masking the true metabolic state. After starting treatment, subsequent lactic acid measurements should be taken at appropriate intervals (typically 2-6 hours later) to assess clearance and treatment effectiveness 1. This sequential monitoring helps determine if perfusion is improving and if the underlying cause of lactic acidosis is being adequately addressed.
Key points to consider when evaluating lactic acid levels in patients with sepsis or shock include:
- Obtaining a baseline lactic acid measurement before administering a fluid bolus
- Using lactate levels to guide resuscitation efforts and monitor response to treatment
- Checking lactate levels at regular intervals (typically 2-6 hours) after starting treatment
- Being aware that rising or persistently elevated lactate levels despite treatment may indicate ongoing tissue hypoperfusion requiring escalation of care 1.
From the FDA Drug Label
In metabolic acidosis associated with shock, therapy should be monitored by measuring blood gases, plasma osmolarity, arterial blood lactate, hemodynamics and cardiac rhythm. The answer to when to check lactic acid is: after bolus and during therapy, as indicated by the need to monitor arterial blood lactate during the treatment of metabolic acidosis associated with shock 2.
- Monitoring should be done to assess the response to therapy and adjust the treatment plan accordingly.
- The timing of lactate checks is not explicitly stated to be only before or only after the bolus, but rather as part of the ongoing monitoring of the patient's condition during therapy.
From the Research
Lactic Acid Measurement Timing
- The optimal timing for checking lactic acid levels in relation to bolus administration is not explicitly stated in the provided studies 3, 4, 5, 6, 7.
- However, the studies suggest that lactate clearance and changes in lactate levels over time are important prognostic indicators in critically ill patients 3, 6.
- It is implied that lactate levels should be monitored regularly, but the specific timing in relation to bolus administration is not clearly defined 3, 4, 5, 6, 7.
Importance of Lactate Clearance
- Lactate clearance is a significant predictor of mortality in severe sepsis patients with lactic acidosis 3.
- A decrement in lactate clearance of at least 10% for the first 6 hours, 24 hours, and 48 hours of treatment was more dominant among survivors than non-survivors 3.
- Lactate clearance at a discrete time point seems to be a more reliable prognostic index than initial lactate value in severe sepsis patients with lactic acidosis 3.
Clinical Significance of Lactate Measurement
- Lactate is one of the most crucial intermediates in carbohydrate and nonessential amino acid metabolism 4.
- Elevated lactate levels in critically ill patients have important implications for morbidity and mortality 4, 6, 7.
- Lactate measurement can be used to guide resuscitation in patients with increased lactate levels, but its use is more complex than suggested by some guidelines 6.