Background: This study aimed to evaluate the BAL fluids findings in children with chronic unexplained cough (Group 1). Children without pulmonary or systemic disease, with normal physical examination and normal chest radiographs who underwent elective surgery, served as the control group (Group 2).
Methods: Bronchoscopy with BAL was performed in all subjects. In Group 1, 24-hour multichannel intraluminal impedance-pH monitoring (24h MII-pH) was performed as a part of diagnostic work-up of chronic unexplained cough.
Results: A total of 50 children (F/M 27/23) participated in the study, 34(68%) in Group 1, and 16(32%) in Group 2. A significant difference was found between the groups in the total number of cells in BAL fluid cytology [191(range 24-12747 cells/?L), and 105(range 41-233 cells/?L), p=0.043], and in the percentage of lipid-laden macrophages expressed as a ratio to the total amount of alveolar macrophages (ratio(%) LLM/AM) (5.5(range 0-45%), and 0(range 0-4), p < 0.001). In addition, the number of children with positive microbiological findings of BAL was significantly higher in group 1 compared to group 2 [8(24%), and 0(0%) (p=0.034)].

GERD based on MII was found in 18 (53%) children with chronic cough. In children with GERD only the percentage of lipidophages in BAL was significantly higher than in children without GERD [median 7.5% (4-45) in GERD+ vs median 5% (0-30) in GERD-; p=0.022].
Conclusion: Bronchoscopy with BAL fluid cytology and MII-pH monitoring can provide valuable information in the evaluation of children with chronic unexplained cough.