Early prediction of chronic lung disease by tracheal aspirate cytology in ventilated newborns

We assessed the specificity of squamous metaplasia in tracheal aspirates of 69 ventilated newborns (gestational age 25-41 weeks) between days 3 and 7 of life for prediction of chronic lung disease (CLD). CLD was diagnosed when the patient was still requiring ventilation or supplementary oxygen at the postconceptional age of 36 weeks (or postnatal age of 28 days for babies born after 32 weeks gestation) and showed X-ray changes compatible with CLD. In the total population the presence of squamous metaplasia had a sensitivity of 59% and a specificity of 74% for the early diagnosis of CLD. The combination of squamous metaplasia and very low birth weight (VLBW) had a much higher specificity (94%), but a lower sensitivity (45%). Our results show that the presence of squamous metaplasia in VLBW babies during the 1st week of life predicts development of CLD with a specificity of 94% and may be helpful for entering patients into early treatment protocols or trials when a high risk population needs to be identified. As sensitivity of this approach is only 45%, further studies are needed to evaluate the predictive value of the combination of cytology with other markers in tracheal aspirate specimens. The presence of squamous metaplasia in tracheal aspirates of VLBW babies between days 3 and 7 of life is significantly associated with the development of chronic lung disease. Simple microscopic evaluation of fresh tracheal aspirates enables us to identify patients at high risk of CLD at a very early stage.