Magentic Resonance Imaging Evaluation of Regional Lung Vts in Severe Neonatal Bronchopulmonary Dysplasia.

Rationale: Bronchopulmonary dysplasia is a heterogeneous lung disease characterized by regions of cysts and fibrosis, but methods for evaluating lung function are limited to whole lung rather than specific regions of interest.Objectives: Respiratory-gated, ultrashort echo time magnetic resonance imaging was used to test the hypothesis that cystic regions of the lung will exhibit a quantifiable Vt that will correlate with ventilator settings and clinical outcomes.Methods: Magnetic resonance images of 17 nonsedated, quiet-breathing infants with severe bronchopulmonary dysplasia were reconstructed into end-inspiration and end-expiration images. Cysts were identified and measured by using density threshold combined with manual identification and segmentation. Regional Vts were calculated by subtracting end-expiration from end-inspiration volumes in total lung, noncystic lung, total-cystic lung, and individual large cysts.Measurements and Main Results: Cystic lung areas averaged larger Vts than noncystic lung when normalized by volume (0.8 ml Vt/ml lung vs. 0.1 ml Vt/ml lung, P < 0.002). Cyst Vt correlates with cyst size (P = 0.012 for total lung cyst and P < 0.002 for large cysts), although there was variability between individual cyst Vt, with 22% of cysts demonstrating negative Vt. Peak inspiratory pressure positively correlated with total lung Vt (P = 0.027) and noncystic Vt (P = 0.015) but not total lung cyst Vt (P = 0.8). Inspiratory time and respiratory rate did not improve Vt of any analyzed lung region.Conclusions: Cystic lung has greater normalized Vt when compared with noncystic lung. Ventilator pressure increases noncystic lung Vt, but inspiratory time does not correlate with Vt of normal or cystic lung.

Evaluation of Lung Injury in Infants with Congenital Diaphragmatic Hernia.

BACKGROUND/PURPOSE: The presence of lung injury and the factors that contribute to it in infants with congenital diaphragmatic hernia (CDH) have not been objectively measured during their clinical course. In adults with acute respiratory distress syndrome, higher serum levels of surfactant protein D (SP-D) are linked to lung injury and worse outcomes. We hypothesized that serum SP-D levels would be elevated in CDH infants and that the levels would correlate to the amount of lung injury present. METHODS: In this retrospective cohort study, serum SP-D levels were analyzed in 37 CDH infants and 5 control infants using a commercially available enzyme-linked immunosorbent assay kit. RESULTS: Infants with more severe CDH had a statistically significant increase (p < 0.001) in serum SP-D over their first month of life. SP-D levels in CDH infants were similar to control infants while on extracorporeal membrane oxygenation (ECMO) but were 2.5-fold higher (p = 0.03) than controls following ECMO termination. SP-D levels increased 1.6-fold following surgical repair of the diaphragm and were significantly higher in the second week following surgery when compared to pre-operative levels (p < 0.03). CONCLUSIONS: These results demonstrate that CDH infants experience lung injury during the first week of life, around the time of surgery, and at the time of ECMO termination. Level II prognosis study.