Intercenter variability and factors associated with survival without bronchopulmonary dysplasia in extremely preterm newborns

[Epidemiology and risk factors for bronchopulmonary dysplasia in prematures infants born at or less than 32 weeks of gestation]

OBJECTIVES

To describe risk factors of bronchopulmonary dysplasia in very preterm infants in the first weeks of life.

MATERIAL AND METHODS

Retrospective cohort study of preterm infants ≤ 32 weeks of gestational age and birth weight ≤ 1500 g. A multivariate logistic regression analysis was performed to identify independent risk factors for bronchopulmonary dysplasia in the first weeks of life.

RESULTS

A total of 202 newborns were included in the study (mean gestational age 29.5 ± 2.1 weeks), 61.4% never received invasive mechanical ventilation. The incidence of bronchopulmonary dysplasia was 28.7%, and 10.4% of the patients were diagnosed with moderate-severe bronchopulmonary dysplasia. Bronchopulmonary dysplasia was independently associated with gestational age at birth (p < 0.001; OR = 0.44 [95% CI = 0.30-0.65]), the need for mechanical ventilation on the first day of life (p = 0.001; OR = 8.13 [95% CI = 2.41-27.42]), nosocomial sepsis (p < 0.001; OR = 9.51 [95% CI = 2.99-30.28]) and FiO2 on day 14 (p < 0.001; OR = 1.39 [95% CI = 1.16-1.66]). Receiving mechanical ventilation at the first day of life (p = 0.008; OR = 5.39 [95% CI = 1.54-18.89]) and at the third day of life (p = 0.001; OR = 9.99 [95% CI = 2.47-40.44]) and nosocomial sepsis (p = 0.001; OR = 9.87 [95% CI = 2.58-37.80]) were independent risk factors for moderate-severe bronchopulmonary dysplasia.

CONCLUSIONS

Gestational age at birth, mechanical ventilation in the first days of life and nosocomial sepsis are early risk factors for bronchopulmonary dysplasia. The analysis of simple and objective clinical data, allows us to select a group of patients at high risk of bronchopulmonary dysplasia in whom it could be justified to act more aggressively, and shows areas for improvement to prevent its development or reduce its severity.

Interactive and independent effects of early lipopolysaccharide and hyperoxia exposure on developing murine lungs

Bronchopulmonary dysplasia (BPD)-associated pulmonary hypertension (PH) is a chronic infantile lung disease that lacks curative therapies. Infants with BPD-associated PH are often exposed to hyperoxia and additional insults such as sepsis that contribute to disease pathogenesis. Animal models that simulate these scenarios are necessary to develop effective therapies; therefore, we investigated whether lipopolysaccharide (LPS) and hyperoxia exposure during saccular lung development cooperatively induce experimental BPD-PH in mice. C57BL/6J mice were exposed to normoxia or 70% O₂ (hyperoxia) during postnatal days (PNDs) 1-5 and intraperitoneally injected with varying LPS doses or a vehicle on PNDs 3-5. On PND 14, we performed morphometry, echocardiography, and gene and protein expression studies to determine the effects of hyperoxia and LPS on lung development, vascular remodeling and function, inflammation, oxidative stress, cell proliferation, and apoptosis. LPS and hyperoxia independently and cooperatively affected lung development, inflammation, and apoptosis. Growth rate and antioxidant enzyme expression were predominantly affected by LPS and hyperoxia, respectively, while cell proliferation and vascular remodeling and function were mainly affected by combined exposure to LPS and hyperoxia. Mice treated with lower LPS doses developed adaptive responses and hyperoxia exposure did not worsen their BPD phenotype, whereas those mice treated with higher LPS doses displayed the most severe BPD phenotype when exposed to hyperoxia and were the only group that developed PH. Collectively, our data suggest that an additional insult such as LPS may be necessary for models utilizing short-term exposure to moderate hyperoxia to recapitulate human BPD-PH.