Lactic Acidosis: Causes, Diagnosis, and Treatment

Introduction to Lactic Acidosis

Elevated lactate levels (>2 mmol/L) are associated with tissue hypoperfusion and worse outcomes, according to the World Journal of Emergency Surgery 1, 2
The presence of lactic acidosis combined with abdominal pain should prompt consideration of early computed tomography angiography (CTA) to rule out mesenteric ischemia, as recommended by the World Journal of Emergency Surgery 2

Sepsis and septic shock are medical emergencies that commonly cause lactic acidosis due to tissue hypoperfusion, as reported by the World Journal of Emergency Surgery and Critical Care Medicine 1, 3
Non-occlusive mesenteric ischemia (NOMI) can lead to lactic acidosis due to inadequate intestinal perfusion, according to the World Journal of Emergency Surgery 2
Cardiac failure and low flow states can lead to tissue hypoxia and subsequent lactate elevation, as noted by the World Journal of Emergency Surgery 2

D-dimer >0.9 mg/L has been reported as a potential marker for intestinal ischemia with specificity, sensitivity, and accuracy of 82%, 60%, and 79%, respectively, by the World Journal of Emergency Surgery 2
No laboratory studies alone are sufficiently accurate to identify the presence or absence of ischemic or necrotic bowel, although elevated lactate and D-dimer may assist in diagnosis, as stated by the World Journal of Emergency Surgery 2

Initial resuscitation should include at least 30 mL/kg of IV crystalloid fluid within the first 3 hours for sepsis-induced hypoperfusion, as recommended by Critical Care Medicine and Intensive Care Medicine 3, 4
Target mean arterial pressure of 65 mmHg in patients with septic shock requiring vasopressors, according to Intensive Care Medicine 4, 5
Guiding resuscitation to normalize lactate levels is suggested in patients with elevated lactate as a marker of tissue hypoperfusion, as reported by Critical Care Medicine and Intensive Care Medicine 3, 4

Lactate levels should be monitored during treatment as they have prognostic significance, according to Critical Care Medicine and Intensive Care Medicine 3, 4
Plain radiography has limited value in diagnosing conditions like mesenteric ischemia that may cause lactic acidosis, as noted by the World Journal of Emergency Surgery 2

The Society of Critical Care Medicine recommends assessing fluid responsiveness dynamically rather than assuming more volume is the answer, using methods such as passive leg raising with cardiac output monitoring or respiratory variation in vena cava diameter to determine if additional fluids will help 6, 7
A lactate level >4 mmol/L indicates severe tissue hypoperfusion and is associated with significantly worse outcomes, with levels of 5 mmol/L placing patients in a high-risk category 8, 7
The European Society of Intensive Care Medicine suggests that fluid responsiveness should be assessed before additional boluses, and that vasopressors should be started if MAP <65 mmHg or signs of poor perfusion persist 6

The American College of Surgeons recommends obtaining CT angiography urgently if there is any abdominal pain, peritoneal signs, or unexplained persistent lactate elevation, as this can help diagnose mesenteric ischemia 7
The World Society of Emergency Surgery suggests that right-sided abdominal pain with diarrhea and elevated lactate in a critically ill patient is highly suggestive of non-occlusive mesenteric ischemia (NOMI), which can occur in low-flow states despite aggressive resuscitation 7

The Surviving Sepsis Campaign recommends starting broad-spectrum antibiotics immediately if not already given, as sepsis is a medical emergency and bacterial translocation from gut ischemia is common 7
The Society of Critical Care Medicine suggests that vasopressors should be used to target a MAP ≥65 mmHg, and that repeat lactate levels should be checked within 6 hours to assess response to resuscitation 6

The European Society of Intensive Care Medicine warns against continuing blind fluid administration beyond initial resuscitation without assessing fluid responsiveness, as this risks abdominal compartment syndrome and worsens gut perfusion 7
The American College of Emergency Physicians advises against attributing persistent lactate elevation solely to the LR infusion, as this delays recognition of serious underlying pathology 7