Comparison of differential cytology between bronchoscopic bronchoalveolar lavage and non-bronchoscopic bronchoalveolar lavage in healthy children

Abstract

Introduction: Bronchoalveolar lavage (BAL), an important tool in the assessment of the lower respiratory tract, can be obtained during flexible bronchoscopy as well as non-bronchoscopically. There are relatively little data in healthy children and no data that compared these techniques. In 100 children without respiratory disease, we described (i) the BAL differential cellular count and its correlation with age, and (ii) compared the differential cytology between non-bronchoscopic BAL (NB-BAL) and bronchoscopic BAL (B-BAL). Methods: Children who underwent B-BAL or NB-BAL, with no history of chronic cough and no acute respiratory infection in the preceding 4 weeks were included. BAL was obtained according to European Respiratory Society guidelines. For B-BAL, a sterile normal saline solution in three aliquots of 1 ml/kg (maximum 20 ml) was instilled into the right middle lobe (first and third aliquots) and lingula (second aliquot) and the return was suctioned into a mucus trap. The first and second aliquots were pooled for microbiological examination, while the third aliquot was used for cytology. For NB-BAL, with the child's head turned to the left, an 8F catheter was inserted through the endotracheal tube until it was wedged. Sterile normal saline (1 ml/kg, maximum 20 ml) was instilled and collected for microbiology examination. A further 1 ml/kg (maximum 20 ml) was instilled and the second collection was utilized for cytology. Results: The median age of the total cohort (42 B-BAL and 58 NB-BAL) was 7.4 years (range 8 days to 16.6 years). However, the NB-BAL group was significantly older (8.2 years, IQR 5.4-12.5 years, vs. B-BAL 3.3 years, IQR 0.9-9 years). In the pooled grouped, the median total cell count was 10.4 x104 per milliliter (IQR 5.7- 18.2x104), macrophage (89.5%, IQR 82.3-93%), lymphocytes (5%, IQR 3-10%) and neutrophils (4%, IQR 2-7%). The total cell count and lymphocyte percentage were inversely correlated with age while the macrophage percentage was positively correlated with age. In univariate analysis, macrophage percentage was significantly higher in NB-BAL (91%, IQR 87-94%) compared to B-BAL (85%, IQR 78- 90%) with lower lymphocyte percentage (NB-BAL (4%, IQR 2-6%) versus B-BAL (10%, IQR 4-13%)). However, when adjusted for age using regression statistics, these differences were not significant. There was no significant difference in the total cell count (NB-BAL 9.3x104/mL, IQR 4.5-15.3x104/mL versus B-BAL 11.8x104/mL, IQR 8-22.1x104/mL) and neutrophil percentage (NB-BAL 4.5%, IQR 2.8%- 7% versus B-BAL 3.5%, IQR 1.8-8%) between the two groups. There was no significant difference in the differential cytology with age in both B-BAL and NB-BAL. Conclusion: NB-BAL provides comparable information on the cellularity components of BAL when compared to B-BAL and should be considered an alternative. As age influences cellular differential count, age-matched data are required for comparative studies on BAL in children.L6287107862019-08-05 <br />