Elevated Lactate & Lactate in Sepsis
The most worrisome cause of lactate elevation is an elevated lactate from tissue hypo-perfusion & shock, resulting in decreased oxygen delivery to the cells. However, the differential for lactate elevation is broader than simply “shock states.”
Patients with liver disease such cirrhotics & alcoholics will have poor lactate clearance and can have an elevated lactate level due to hepatic dysfunction. Medications can also lead to a high lactate level, such as albuterol (and other sympathomimetics), metformin, alcohol, & carbon monoxide poisoning (inability to deliver oxygen to tissues). Lastly, muscle activity in heavy exercise and seizures will also result in an elevated lactate level.
In patients with suspected sepsis, why do we get an initial lactate and repeat it in 6 hours?
There is an established link between mortality and elevated lactate. This is also a core quality measure decided by the Center of Medicare and Medicaid Services that should be met in patients presenting in sepsis. This is based off of SEP-1, which is controversial and has more or less protocoled sepsis care. The bottom line is CMS wants this measure completed and they hold the purse strings.
What does the 2021 Surviving Sepsis Campaign say about lactate?
“For adults suspected of having sepsis, we suggest measuring blood lactate. Weak recommendation, low-quality evidence ”
“For adults with sepsis or septic shock, we suggest guiding resuscitation to decrease serum lactate in patients with elevated lactate level, over not using serum lactate.
During acute resuscitation, serum lactate level should be interpreted considering the clinical context and other causes of elevated lactate
Weak recommendation, low-quality evidence”
The latest surviving sepsis guidelines do recommend measuring lactate levels and guiding resuscitation to decrease serum lactate over not using serum lactate. The panel does recognize that normal serum lactate levels are not achievable in all patients with septic shock, but many studies support resuscitative strategies that decrease lactate toward normal. Serum lactate level should be interpreted within the clinical context and other causes of elevated lactate should be considered. Also, lactate alone is neither sensitive nor specific enough to rule-in or rule-out sepsis.
In summary, remember we are concerned an elevated lactate may be due to a shock state, such as sepsis. The differential though is broader than shock/hypotension. Lactate can be useful in both diagnosing and guiding resuscitation in sepsis/septic shock, but its use is nuanced and should be interpreted in the wider clinical setting. Remember to get an initial and repeat lactate in suspected sepsis to fulfill the core quality measures set by CMS.
Sources:
Evans, L., Rhodes, A., Alhazzani, W. et al. Surviving sepsis campaign: international guidelines for management of sepsis and septic shock 2021. Intensive Care Med 47, 1181–1247 (2021). https://doi.org/10.1007/s00134-021-06506-y
https://emcrit.org/pulmcrit/acep-septic-shock/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3975915/
Moving Beyond the Centers for Medicare and Medicaid Services' "Severe Sepsis and Septic Shock Early Management Bundle" Core Quality Measure, Jeremy Faust, annals of emergency medicine