Clinical question: Are high plasma lactate levels associated with mortality and clinical deterioration among patients with acute pulmonary embolism (PE)?
Background: Prognostic clinical markers are limited in patients presenting with acute PE, especially among normotensive individuals. Plasma lactate concentration is a marker of tissue hypoperfusion that has been used to risk-stratify patients with sepsis and trauma. It is unknown whether elevated lactate levels predict poor outcomes in acute PE.
Study design: Prospective cohort.
Setting: ED in a large teaching hospital in Italy.
Synopsis: Consecutive adult patients with acute PE diagnosed by spiral computed tomography or lung scan were included. Plasma lactate levels were tested in all patients at presentation, and levels of ≥2 mmol/L were considered abnormal. The primary endpoint was all-cause death within 30 days, and the secondary endpoint was the composite of all-cause death and PE-related clinical deterioration and death.
Of the 270 patients, 81 (30%) had abnormal lactate levels, though only 12 (4.4%) had shock or hypotension. Patients with elevated lactate had higher mortality compared with patients with lower levels (17.3% vs. 1.6%, OR 12.95, 95% CI 3.43-58.73). Plasma lactate ≥2 mmol/L was associated with higher all-cause mortality (HR 11.67, 95% CI 3.32-41.03) and the composite endpoint (HR 8.14, 95% CI 3.83-17.34). This association was independent of the presence of hypotension, right ventricular dysfunction, or elevated troponin.
Limitations include the single study site (which limits generalizability of the findings) and that lactate levels were only checked once (which might not have fully reflected each patient’s clinical picture). The authors suggest that plasma lactate levels might have utility in determining which patients should be treated more aggressively for PE.
Bottom line: In patients presenting with acute PE, elevated plasma lactate levels are associated with increased risk of short-term mortality and morbidity, independent of the presence of hypotension or markers of right ventricular injury.
Citation: Vanni S, Viviani G, Baioni M, et al. Prognostic value of plasma lactate levels among patients with acute pulmonary embolism: the thrombo-embolism lactate outcome study. Ann Emerg Med. 2013;61:330-338.