Development of Bronchopulmonary Dysplasia and the Peripheral and Tracheal Aspirate Neutrophil Counts and Cytokine Concentrations of Tracheal Aspirate in Preterm Infants with Acute Respiratory Failure

ABSTRACT

PURPOSE: The purposes of this study were to analyze the association of peripheral and tracheal aspirate neutrophil counts and tracheal aspirate cytokines [interleukin (IL)-8, IL-6, IL-10] concentrations with the development of bronchopulmonary dysplasia (BPD) in preterm infants intubated due to acute respiratory failure, and to speculate the causal relationship between the prenatal or early postnatal inflammation of the lung and the development of BPD. METHODS: A prospective study was conducted from April 1997 to March 1998 in 27 preterm infants, who were admitted to the neonatal intensive care unit of Seoul National University Children's Hospital and intubated due to acute respiratory failure. Tracheal aspirates were collected via endotracheal tube immediately after intubation. Tracheal aspirate neutrophil counts were measured by cytospin method and, cytokine concentrations were measured by ELISA method in the supernatant after centrifugation. RESULTS: BPD was diagnosed in 59.3% (16/27) of preterm infants. Compare to the non-BPD group, the BPD group had lower gestational age (27.6+/-1.3 weeks versus 32.0+/- 1.2 weeks), lower birth weight (1,112+/-228 g versus 1,666+/-334 g), higher incidence of patent ductus arteriosus (27.3% versus 81.3%), increased number of neutrophils (80,337+/-133,993/mL versus 2,672+/-6,600/mL), and increased IL-8 concentration (1,045.4+/-1,346.5 pg/mL vs 106.9+/-151.0 pg/mL) of tracheal aspirate. After control of compounding variables, increased IL-8 concentration of tracheal aspirate was found to be an independent risk factor for BPD (odds ratio; 27.7, 95% confidence interval; 1.8-436.2). CONCLUSION: Prenatal or immediate postnatal lung inflammation is an important risk factor for the development of the BPD, and the lung injuries responsible for the development of BPD might begin at the prenatal or immediate postnatal period.