|Year : 2020 | Volume
| Issue : 6 | Page : 307-308
Lactate clearance - Is it an alarm for escalation or an endpoint of resuscitation?
Department of Pediatrics, Division of Pediatric Critical Care, Gleneagles Global Heath City, Chennai, Tamil Nadu, India
|Date of Submission||09-Sep-2020|
|Date of Acceptance||21-Sep-2020|
|Date of Web Publication||11-Nov-2020|
Dr. Vijai Williams
Department of Pediatrics, Division of Pediatric Critical Care, Gleneagles Global Heath City, Chennai, Tamil Nadu
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Williams V. Lactate clearance - Is it an alarm for escalation or an endpoint of resuscitation?. J Pediatr Crit Care 2020;7:307-8
Lactate has been a molecule of interest in septic shock since its description in 1843 by Johann Scherer. Lactate is produced when pyruvate cannot enter the mitochondria to participate in Krebs cycle in anaerobic conditions. This is an adaptive mechanism to produce energy in a stressed state through shuttle mechanisms. Sepsis elicits a cytokine response that increases glycolysis and impairs pyruvate dehydrogenase activity causing excess lactate formation even in aerobic conditions. Lactate produced gets metabolized predominantly through liver and kidneys. Hepatic or renal dysfunction can impair lactate clearance. Thus, in critically ill children, both excess production and hampered clearance result in hyperlactatemia. In this issue, Gulla et al. have tried to elucidate the role of serial lactate measurement and its clearance as a predictor of early intensive care unit and in hospital mortality.
In this small prospective observational study, (n = 43), the authors. have chosen early mortality (within 72 h) as their primary outcome with a rationale to identify patients who are at an increased risk of mortality or need of organ support. Observational studies have demonstrated an association of hyperlactatemia (>4 mmol/L) with unfavorable outcomes in the form of multiorgan dysfunction syndrome (MODS) and mortality in septic shock., This study shows a similar trend of higher lactate among nonsurvivors over the initial 24 h. The median value at various time points among survivors lies between 1 and 1.9 mmol/L and among nonsurvivors between 1.8 and 3 mmol/L. Lactate clearance was 15.1% in survivors and 33.2% in nonsurvivors. This may imply that an absolute value of >2 mmol/L or failure of lactate clearance may act as alarms for re-evaluation of ongoing therapy and need for escalation of support.
The key components of the management of septic shock include fluids, inotropy, antibiotics, and source control. Lactate clearance during management can be a sign of improvement in circulatory dysfunction with studies demonstrating better clinical outcomes., However, there are several confounders that one has to consider before escalating fluid or inotropic support in those with impaired lactate clearance. Appropriate use of antibiotics and source control are essential in those with impaired lactate clearance. Quantification of organ dysfunctions (MODS score) along with individual organ dysfunction especially liver that clears about 60% of lactate is important to understand lactate clearance. Factors that determine systemic oxygen delivery (anemia, oxygen saturation, and cardiac output), use of catecholamines in septic shock patients, and lactate buffered fluid in continuous hemofiltration can contribute to hyperlactatemia. In this study, a good correlation of lactate beyond 24 h with pediatric logistic organ dysfunction score suggests that organ dysfunction rather than inadequate resuscitation could have contributed to hyperlactatemia. Data on other confounders are needed before attributing hyperlactatemia to mortality. Thus, children with hyperlactatemia and failure of lactate clearance need close monitoring with the assessment of correctable factors and ensuing organ dysfunction.
Lactate-guided resuscitation has been suggested to significantly reduced hospital mortality in adult trials. However, in resource poor settings where lactate measurement is not routinely available, clinicians may need to be dependent on other parameters while resuscitating these children. This was explored in the ANDROMEDA-SHOCK trial where the exclusive use of capillary refill time compared to lactate was equally good as a resuscitation target in septic shock. Owing to lack of pediatric trials on lactate-guided resuscitation, there are no recommendations on using lactate values to guide therapy in children with septic shock or MODS. The surviving sepsis guidelines suggests using trends in lactate levels, in addition to clinical assessment, to guide resuscitation of children with septic shock and other sepsis-associated organ dysfunction. This study does not demonstrate any association of lactate levels beyond 24 h in predicting hospital mortality. Having said this, multiple limitations including small sample size, low event rate, failure to quantify, and adjust for confounders may have altered the results. To summarize, factors regulating blood lactate levels can be complex and optimizing circulatory dysfunction is just a spoke in the wheel. Lactate may act as an alarm during resuscitation but not as a standalone endpoint for resuscitation.
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