No abstract

Pulmonary hypertension in the neonate requires treatment with oxygen and positive pressure ventilation, both known to induce lung injury. The direct response of pulmonary artery smooth muscle cells, the most abundant cells in the artery wall, to the stress of positive pressure and hyperoxia has not been previously studied. Pulmonary artery smooth muscle cells were cultured in temperature- and pressure-controlled air-tight chambers under conditions of positive pressure or hyperoxia for 24 h. Control cells were cultured in room air under atmospheric pressure. After the exposure period, culture medium was collected and samples were analyzed by ELISA, Human Cytokine 25-Plex Panel using a Luminex 200 analyzer and Western blot. Secretion of various inflammatory mediators, specifically IL-6, IL-8, IL-2R, MIP-1β, MCP-1, IP-10, IL-7, IL-1RA, and IFN-α, was higher in the positive pressure and hyperoxia groups compared with control. The level of cyclin D1 was decreased in the hyperoxia and positive pressure group compared with control. Levels of fibronectin and α-smooth muscle actin were not different among the groups. Pulmonary artery smooth muscle cells directly produce multiple inflammatory mediators in response to oxidative and biophysical stress in vitro, which may be part of a cascade that leads to the vascular and perivascular changes in pulmonary hypertension.

Our aim for this study was to report pulmonary mechanics in a neonate with a severe case of Barnes syndrome, a rare form of thoracolaryngopelvic dysplasia, and to use these data to guide ventilatory support and serve as a presurgical screening tool. A comprehensive pulmonary function evaluation was performed on a 36-day-old patient with Barnes syndrome who was being mechanically ventilated because of severe pulmonary distress secondary to thoracic dystrophy. The measurements consisted of respiratory volumes including functional residual capacity, ventilatory mechanics including compliance and resistance, and thoracoabdominal synchrony. Chest wall compliance was 64% below normal, and the thoracoabdominal motion was indicative of predominantly abdominal displacement during inspiratory breaths. The lungs were functioning at a low functional residual capacity, resulting in low lung compliance and increased pulmonary resistance. As a result of the evaluation, the patient was recommended for lateral thoracic expansion surgery and the ventilatory management was adjusted to focus on end-distending pressure support.