ANALYSIS OF THE CORRELATION BETWEEN FRACTIONAL CONCENTRATION OF EXHALED NO, CLEARANCE RATE OF BLOOD LACTIC ACID AND LACTIC ACID AND THE SEVERITY OF PATIENTS WITH ACUTE RESPIRATORY DISTRESS SYNDROME

Wei Zhao, Panxin Hu^*

Emergency Department, Taizhou First People's Hospital

Objective: To study the correlation between the fractional concentration of exhaled nitric oxide (FENO), clearance rate of blood lactic acid, and lactic acid and the severity of patients with acute respiratory distress syndrome. 

Methods: Seventy-six patients with acute respiratory distress syndrome admitted to the intensive care unit of our hospital from June 2017 to August 2019 were selected as the study group. The patients were divided into mild (36 cases), moderate (26 cases), and severe (14 cases) groups according to the difference of oxygenation index (OI) and were placed into survival (60 cases) and death (16 cases) groups according to the different prognosis of patients. Twenty-five healthy subjects who underwent a physical examination in our hospital during the same period were selected as the normal group. The severity of the patients was evaluated by their APACHE II score. The FENO of each group using an exhaled nitric oxide (NO) analyzer was determined. The levels of blood lactate at 0 and 24 h in each group were determined with a blood gas analyzer. Pearson correlation analysis was used to determine the relationship between FENO, clearance rate of blood lactic acid, and lactic acid and the severity of patients with acute respiratory distress syndrome. 

Results: Compared with the normal group, the FENO, blood lactic acid at 0 and 24 h, and APACHE II scores in the study group were significantly increased, and the lactic acid clearance rate was significantly reduced (P<0.01). With the increase of disease severity, the FENO, blood lactic acid at 0 and 24 h, and APACHE II scores were significantly increased, and the lactic acid clearance rate was significantly reduced (P<0.01). Compared with the survival group, the FENO, blood lactic acid at 0 and 24 h, and APACHE II scores in the death group were significantly increased, and the lactate clearance rate was significantly reduced (P<0.01). Pearson correlation analysis showed that FENO and blood lactate were positively correlated with the severity of the patients (P<0.05); lactic acid clearance rate was negatively correlated with the severity of the patients (P<0.05). 

Conclusion: The FENO and blood lactate levels of patients with acute respiratory distress syndrome were significantly higher than those of healthy subjects, and the lactate clearance rate was significantly lower, which can be used as important indicators for evaluating patients’ severity and prognosis.