The Use of Infant Pulmonary Function Testing in the Diagnosis of Neuroendocrine Cell Hyperplasia of Infancy.

Background Infant pulmonary function tests (iPFTs) in subjects with neuroendocrine cell hyperplasia of infancy (NEHI) have demonstrated significant expiratory airflow obstruction and air trapping. Research Question Can indexes from iPFTs be used in the diagnosis of NEHI? Study Design and Methods This is an observational case-control study evaluating iPFT results from a registry of patients assessed at the Hadassah Hebrew University Medical Center between 2008 and 2018. We used the Kruskal-Wallis H test to compare iPFT results in infants with NEHI with those in two infants in a disease control group (infants evaluated for recurrent wheezing and infants evaluated owing to prematurity) and those in a spirometry control group of infants with normal expiratory airflow. Receiver operating characteristic (ROC) curves were used to assess the diagnostic accuracy of the iPFT indexes. Results We evaluated iPFT data in 481 infants (15, NEHI; 292, wheezing; 128, premature; and 46, control group). Infants with NEHI had significantly increased trapped air volumes (median functional residual capacity measured with baby-body plethysmograph [FRCpleth] was 199% predicted; median ratio of residual volume to total lung capacity was 59% predicted) when compared with results in all evaluated groups of infants (P  Interpretation Findings on iPFTs of markedly increased air trapping, out of proportion to the degree of airflow limitation, are characteristic of infants with NEHI. iPFT results demonstrating an FRCpleth ≥ 150% predicted are highly specific for NEHI and may aid in early diagnosis. Further research is required to confirm these findings in a prospective cohort and to understand the pathophysiologic explanation for these findings.