Objective: In addition to the previous classification of chronic lung disease (CLD) O2 dependency at 36 weeks of postmenstrual age, a new definition of CLD has recently been proposed: new bronchopulmonary-dysplasia (BPD). This uses total duration of O2 supplementation and positive pressure requirements to delineate three degrees of severity (mild, moderate, and severe) according to the respiratory status at 36 weeks postmenstrual age. We analyzed the balance of serum proinflammatory and profibrotic/angiogenic cytokine concentrations in relation to CLD and the new BPD definition.
Design and setting: Descriptive study in a third-level neonatal ICU.
Patients: Thirty-one preterm neonates with a gestational age of 24-29 weeks were studied to evaluate their serum cytokine concentration; they were previously enrolled in a randomized clinical trial to compare the effects of high-frequency oscillatory ventilation vs. intermittent mandatory ventilation in terms of pulmonary mechanics and lung cytokines. Serum samples were collected on days 1, 3, and 5 after birth until extubation to detect the levels of three proinflammatory cytokines plus four profibrotic/angiogenic cytokines, and correlations were examined to old CLD and new BPD. Ventilation treatments were distributed homogeneously between the groups and did not interfere with the results presented here.
Results and conclusions: Old CLD development, mainly corresponding to the moderate/severe forms of new BPD, was associated with increased proinflammatory and profibrotic/angiogenic cytokines, while mild forms of new BPD were characterized only by increases in profibrotic/angiogenic cytokines, suggesting a different balance of two pathogenic mechanisms in different phases of the disease.