Aim of the study is to find out early diagnostic markers of chronic lung disease (CLD) in the tracheal lavage fluid (TLF) of high-risk neonates using the cytologic examination.
Material and methods: TLF from forty newborn infants treated by conventional ventilation (CV) and oxygen were studied. The infants were divided into three groups: I--12 term and 11 premature infants without signs of CLD on the 28th day of birth; II group--15 premature infants with persistent respiratory distress and oxygen dependence till the 28th day of life without signs of CLD after 36 weeks of gestation and III group--5 premature infants treated by CV more than 14 days with signs of CLD after 36 weeks of gestation. The diagnostic tracheal lavage (TL) was performed between the 4th and 10th day from the beginning of CV. A standart method for TL of neonates was used. The cytologic samples were prepared from filtrated TLF and examined by light microscopy. The percentage count of blood cell elements and the ratio between normal and metaplastic bronchoepithelial cells were determined and compared between the three groups.
Results: We found similar mean values of the cellular elements and the ratioes of the term and the preterm babies from I group: alveolar macrophages (AM)--75.8 +/- 11.35%; neutrophils (Neu)--22.78 +/-10.8%; lymphocytes (Ly)--1.1 +/- 0.32% and ratio between normal and metaplastic (N/M ratio) epithelial cells = 3,17:1. In the II group the mean value of Neu was 31.57 +/- 9.2%, which is higher than the Neu mean value of the I group, but the difference is not significant (p = 0.2). The mean value of AM was 65.7 +/- 9.8% and the of as well as between I and II group (p < 0,05) and between II and III group (p < 0.05).
Conclusion: The percentage of the metaplastic respiratory cells in TLF has an early diagnostic value for CLD in high-risk newborn infants: metaplasia in less than 40% of the epithelial cells can be accepted as transitional, since it is reversible; mataplasia between 40% and 80% of the cells is associated with a risk of broncho-obstructive syndrome in early infancy. Squamous metaplasia of more than 80% of the cells in TLF has a diagnostic importance for CLD.