From the Guidelines
Elevated lactate levels of 8 mmol/L, despite a normal pH, indicate tissue hypoperfusion and require immediate medical attention to address the underlying cause and support vital functions. A normal pH in the human body is typically around 7.35 to 7.45, which represents a slightly alkaline state [ 1 ]. This narrow range is crucial for proper cellular function and enzyme activity. A normal lactate level in the blood is generally less than 2 mmol/L (or less than 18 mg/dL) when at rest.
Key Points to Consider
- A lactate level of 8 mmol/L is significantly elevated and indicates lactic acidosis, which is a serious condition requiring immediate medical attention.
- This elevation typically occurs when tissues receive insufficient oxygen, causing cells to switch to anaerobic metabolism, which produces lactate as a byproduct.
- Common causes include severe infection (sepsis), shock, cardiac arrest, severe trauma, or certain medications and toxins.
- Treatment focuses on addressing the underlying cause while supporting vital functions, which may include fluid resuscitation, antibiotics for infection, vasopressors for shock, mechanical ventilation for respiratory failure, and in some cases, bicarbonate therapy for severe acidosis [ 1 ].
Recommendations for Management
- Guiding resuscitation to normalize lactate in patients with elevated lactate levels as a marker of tissue hypoperfusion is suggested [ 1 ].
- Elevated lactate is associated with increased mortality, so prompt recognition and intervention are essential for improving outcomes.
- The Surviving Sepsis Campaign recommends protocolized, quantitative resuscitation of patients with sepsis-induced tissue hypoperfusion, defined as hypotension persisting after initial fluid challenge or blood lactate concentration >4 mmol/L [ 1 ].
From the Research
Significance of Normal pH and Elevated Lactate Levels
- Elevated lactate levels, such as 8 mmol/L, can be an indicator of tissue hypoperfusion or hypoxia, but it is not a specific marker and can have other causes 2, 3.
- Lactate levels can be elevated due to increased aerobic glycolysis during the stress response, and it may represent an important energy source for patients in critical condition 2.
- Hyperlactatemia is common among critically ill patients, and lactate levels and their trend may be reliable markers of illness severity and mortality 2, 4.
- The relationship between lactate levels and tissue hypoxia/hypoperfusion is complex, and lactate may not always reflect fluid-responsive hypoperfusion 4, 5.
- Elevated lactate levels can be associated with increased mortality, length of ICU stay, mechanical ventilation, and shock 6.
- Initial elevated lactate levels can be a factor of poor prognosis, and the cut-off point that best predicts mortality may need to be adjusted based on the severity of the patient's condition 6.
Clinical Implications
- Measuring blood lactate is recommended to stratify patients based on the need for fluid resuscitation and the risks of multiple organ dysfunction syndrome and death 2.
- Lactate clearance may be a useful therapeutic target for resuscitation, but it is not a reliable marker of tissue hypoxia/hypoperfusion 4, 5.
- Monitoring lactate can ensure adequate peripheral perfusion during resuscitation, but it should be used in conjunction with other markers of tissue hypoperfusion 5, 6.
- The use of lactate levels to guide resuscitation in critically burned patients is controversial, and its usefulness and limitations need to be considered 6.