[Efficacy of bronchoalveolar lavage and its influence factors in the treatment of Mycoplasma pneumoniae pneumonia with atelectasis].

Objective: To investigate the efficacy of bronchoalveolar lavage (BAL) and its influence factors in the treatment of Mycoplasma pneumoniae pneumonia (MPP) with atelectasis. Methods: A retrospective case control study was performed on hospitalized MPP patients with atelectasis and received BAL in the Department of Pulmonology, Children's Hospital Zhejiang University School of Medicine from January 1, 2015 to July 31, 2017. Fever relieved in 48 hours and chest imaging improved in one week after BAL were considered effective. Clinical data, including age, sex, blood routine tests, lactate dehydrogenase (LDH), cytokines, complications, fever duration before BAL, course of disease before BAL, sputum plug, atelectasis area and its CT values of atelectasis site were collected. Student's t test, Mann-Whitney U test, or chi square test were used. Results: (1) A total of 163 patients were enrolled, including 69 boys and 94 girls, with the ratio of 1∶1.36. Their ages ranged from 6 months to 12.6 years. (2) On the day of bronchoscope, 113 patients still had fever. They were divided into effective group ( n= 66) and ineffective group ( n= 47) according to whether fever was relieved in 48 hours after BAL. The effective group were found to have less sputum plug compared with the ineffective group (33% (22/66) vs . 57% (27/47), χ(2)=6.499, P= 0.011). The other factors such as sex, age, fever duration before BAL, course of disease before BAL, C reactive protein (CRP), LDH, IL-2, IL-4, IL-6, IL-10, TNF, IFN-γ, atelectasis area and CT value showed no significant difference between the two groups (all P >0.05). (3)A total of 122 cases had chest imaging after BAL. According to chest imaging improvement, they were divided into effective group ( n= 81) and ineffective group ( n= 41). The effective group showed lower CT value ((58±9) vs. (63±8) HU, t= -2.436, P= 0.017), IL-6 and IL-10 ( M ( Q (1), Q (3))) (21.0 (1.9, 48.4) vs . 36.4(21.8, 93.6), 4.9 (3.7, 9.6) vs . 7.7 (4.4, 12.0) ng/L, Z= -2.387,-2.009, P= 0.017, 0.045). Sex, age, fever duration before BAL, course of disease before BAL, CRP, LDH, IL-2, IL-4, TNF, IFN-γ, atelectasis area showed no significant differences between the two groups (all P >0.05). (4) Patients were divided into sputum plug group (57 cases) and non sputum plug group (106 cases) according to bronchoscopic findings. The sputum plug group showed higher LDH, CRP, IL-6, IFN-γ, incidence of pleural effusion and extrapulmonary complications (585(433, 833) vs . 369 (312, 588) U/L, 42 (19, 103) vs. 25 (12, 45) mg/L, 38.8 (22.1, 71.3) vs . 20.7 (9.2, 48.3) ng/L, 33.1 (13.5, 89.3) vs. 12.7 (6.5, 33.6) ng/L, 73.7% (42/57) vs. 52.8% (56/106), 40.4% (23/57) vs. 17.0% (18/106)), with statistically significant differences ( Z= -4.865,-3.435,-3.098,-3.704, χ(2)= 0.010, 0.001, all P <0.01) . Additionally, fewer patients showed fever relief within 48 hours after BAL in the cases with sputum plug cases compared those without sputum plug (44.9% (22/49) vs . 68.8% (44/64), χ(2)= 0.011, P= 0.009). Fewer patients showed chest imaging improvement within one week after BAL in the cases with sputum plug compared with those without sputum plug, but did not show significant difference (56.5% (26/46) vs . 72.4% (55/76), χ(2)=0.073, P= 0.056). Conclusions: BAL has some therapeutic effect on fever or atelectasis in MPP children complicated with atelectasis. Chest imaging improvement or fever relief may be hampered by sputum plug, increased IL-6 or IL-10.