Admission Serum Lactate as a Predictor of Mortality in COVID-19 Pneumonia with Acute Respiratory Failure

Abstract

Rationale: Novel coronavirus-19 (COVID-19) has been observed to cause multi-organ failure and death. Lactic acid has been shown to predict worse outcomes in patients with multi-organ failure in various disease processes. During episodes of acute hypoxia there is increased conversion of pyruvate to lactic acid. In COVID-19 patients, the dysregulated inflammatory response, also known as the cytokine storm, has been known to cause acute respiratory distress syndrome (ARDS) causing refractory hypoxemia and worsening lactic acidosis. Various inflammatory markers have been studied to predict outcomes in COVID-19 patients. The objective of this study was to identify whether lactic acid at admission correlated with mortality in patients with acute respiratory failure due to COVID-19. Methods: Seventy-one patients admitted to our hospital with acute respiratory failure due to COVID-19 were studied. Medical records were reviewed to obtain demographics including age, gender, body mass index (BMI), outcome (survivor or non-survivor) and admission lactic acid levels. Pearson's correlation analysis was performed to evaluate the correlation between admission lactic acid levels and mortality. Independent t-test was performed to determine the impact of this parameter on mortality. p < 0.05 was deemed statistically significant. Results: Of the seventy-one (71) patients, admission lactic acid levels were obtained in sixty-four (64) patients. Mean age was 47.7 + 16.7 years, 73% were male, and mean BMI was 32.27 + 2.73 kg/m2. Twelve patients (18.75%) did not survive. The mean admission lactic acid for non-survivors was 2.05 + 1.032 mmol/L and for survivors was 1.16 + 0.85 mmol/L (p = 0.002, independent t-test) [Figure 1]. Pearson's correlation analysis showed a significant correlation between admission lactic acid levels and mortality (r = -0.372, p = 0.002). Conclusions: A lactic acid at admission has a significant correlation with mortality in COVID-19 patients with acute respiratory failure. Further studies are required to assess this correlation and of rise in lactic acid to risk of mortality in patients. In addition, more studies are also needed to determine if there is a specific value of lactic acid that would predict mortality in patients.