Increased laryngeal lavage lipid-laden macrophage index during acute bronchiolitis

Aim: To investigate aspiration risks associated with bronchiolitis in infants using the lipid-laden macrophage index (LLMI) from laryngeal lavages. Methods: Laryngeal lavages from 29 infants with acute bronchiolitis caused by respiratory syncytial virus were evaluated (acute stage). Repeated studies were then performed at 3-4 weeks after the initial study (remission stage). Lavage cell counts and differentials were determined. The amount of lipid per single macrophage was evaluated and the LLMI was determined by evaluating 100 cells. In addition, 24-h pH monitoring (pHm) was performed in 16 patients. Results: The LLMIs in the acute stage were significantly higher than those in the remission stage (p < 0.05). The neutrophil percentage of the laryngeal lavage correlated significantly with the LLMI (r = 0.707, p < 0.0001) during the acute stage of bronchiolitis. When patients were divided into pHm-positive (n = 5) and pHm-negative (n = 11) subgroups, a significant decrease in LLMI between acute and remission stages was noted among the pHm-positive (p < 0.01) subgroup, but not in the pHm-negative subgroup. Conclusion: These findings suggest that there is a transient increased LLMI in patients with bronchiolitis, which could be caused by gastroesophageal reflux.