Infant Pulmonary Function Testing in Pediatric Diffuse Parenchymal Lung Disease.

Topic Importance: Diffuse parenchymal lung disease (DPLD) in pediatrics, also known as children's interstitial lung disease, comprises a diverse group of rare and chronic respiratory disorders affecting the pediatric population. Diagnosing and monitoring these conditions in infants pose significant challenges. Despite advances in genetic diagnostics and imaging technologies, challenges persist, particularly in infants, for whom noninvasive methods are limited, and no optimal technique exists for quantitative follow-up. Although pulmonary function testing (PFT) is an essential tool for evaluating adults and older children, its complexity limits its routine use in infants. In this review, we summarize available data on infant PFT (iPFT) in DPLD, highlight its potential to enhance our understanding of the pathophysiologic features of certain DPLDs, and elucidate its role in disease management. Review Findings: Diverse patterns of iPFT alterations have been observed across different types of DPLD in infants. Specific conditions, such as surfactant dysfunction disorders, neuroendocrine cell hyperplasia of infancy, and congenital heart disease with high pulmonary flow exhibit distinct alteration patterns. These findings enhance our understanding of the pathophysiologic characteristics of these diseases and can aid in their diagnosis and management. Summary: Understanding the nature of iPFT alterations can provide insights into the pathophysiologic features, diagnosis, and management of DPLD in infants. However, the complexity of performing comprehensive PFT in infants restricts its routine use. Advancing the development of precise and accessible techniques for evaluating pulmonary function in infants is crucial to improving management. Given the rarity of DPLD in infants, international collaboration is imperative.