[Effect of alveolar macrophages phagocytosis on prognosis in patients with acute respiratory distress syndrome caused by abdominal infection: a multicenter study].

Objective To investigate the effects of alveolar macrophage phagocytosis on prognosis in patients with acute respiratory distress syndrome (ARDS) caused by abdominal infection. Methods ARDS patients caused by severe intra-abdominal infection admitted to intensive care unit (ICU) of Tianjin Fourth Central Hospital, Tianjin Nankai Hospital, Tianjin First Central Hospital and Tianjin Fifth Central Hospital from June 2016 to March 2018 were enrolled. The gender, age, acute physiology and chronic health evaluationⅡ(APACHEⅡ) within 24 hours of admission, neutral red phagocytosis and alkaline phosphatase activity of macrophages in bronchoalveolar lavage fluid, the length of ICU stay, total hospitalization time, hospitalization expenses, and prognosis were recorded. According to the prognosis, the patients were divided into death group and survival group, and the parameters were compared between the two groups. Pearson test was used to analyze the correlation between neutral red phagocytosis function of macrophages and alkaline phosphatase activity and other indicators. The prognosis was analyzed by binary Logistic regression combined with neutral red phagocytosis and alkaline phosphatase activity in patients, and the predictive value of both subjects on prognosis was analyzed by the receiver operating characteristic (ROC) curve. Results Twenty patients were enrolled in the study, with 8 in the death group and 12 in the survival group. Compared with the survival group, the death group was older (years old: 58.50±14.86 vs. 46.67±13.40), APACHEⅡ score was higher (21.50±3.93 vs. 13.58±4.12), neutral red phagocytosis ability and alkaline phosphatase activity of alveolar macrophages were significantly decreased (A value: 0.265±0.050 vs. 0.338±0.016; μmol/L: 12.06±1.24 vs. 17.96±3.90), and the length of ICU stay was significantly longer (days: 22.00±14.59 vs. 11.50±3.17), hospitalization cost was significantly increased (10 thousand Yuan: 24.17±11.02 vs. 13.44±3.53), the total hospitalization time was shorter (days: 25.25±15.01 vs. 35.67±8.58), and the difference was statistically significant (all P 0.05]. The neutral red phagocytosis ability of alveolar macrophages in ARDS patients caused by abdominal infection was negatively correlated with age, APACHEⅡ score and the length of ICU stay (r value was -0.328, -0.572, -0.809, respectively, all P < 0.05); alkaline phosphatase activity was negatively correlated with age, APACHEⅡ score, the length of ICU stay and hospitalization expenses (r value was -0.334, -0.583, -0.470, -0.517, respectively, all P < 0.05). Binary Logistic regression analysis showed that neutral red phagocytosis [odds ratio (OR) = 0.596, 95% confidence interval (95%CI) = 0.212-0.997] and alkaline phosphatase activity (OR = 0.573, 95%CI = 0.339-0.968) were the influencing factors of prognosis (both P < 0.05). ROC curve analysis showed that the AUC of neutral red phagocytosis ability for prognosis of ARDS patients caused by abdominal infection was 0.948, and the sensitivity and specificity were 91.7% and 87.5% when the off-cut value was 0.317. The AUC of alkaline phosphatase for the prognosis of ARDS patients caused by abdominal infection was 0.813; when the cut-off value was 19.72 μmol/L, the sensitivity was 75.0%, and the specificity was 87.5%. Conclusion The alveolar macrophage phagocytosis dysfunction in ARDS patients caused by severe abdominal infection was not only related to the severity of the disease, but also increased the medical burden of patients, and significantly affected the mortality of such patients. Key words: Abdominal infection; Acute respiratory distress syndrome; Alkaline phosphatase; Neutral red phagocytosis; Prognosis