Abstract Rationale Primary ciliary dyskinesia (PCD) is a genetically heterogeneous disorder of motile cilia, causing chronic sinopulmonary disease and systemic complications. Early diagnosis is challenging due to variable presentation and overlap with other respiratory conditions. Nasal nitric oxide (nNO) measurement is a non-invasive, sensitive screening tool, but young children may struggle with technically adequate maneuvers. The Exhalation Against Resistance (EAR) maneuver has been the preferred collection maneuver to ensure velum closure. More recently, the Single Breath Hold (SBH) technique has been suggested as an alternative method for patients who fail to optimally exhale against resistance. Validating alternative testing methods could benefit patients, particularly young children, who are unable to sustain exhalation. Objective To assess whether the SBH maneuver provides comparable diagnostic performance to EAR for nNO measurement in pediatric PCD screening. Methods This study was approved by the IRB at the Children’s Hospital of Philadelphia (IRB #014568) and all subjects and/or guardians provided informed consent and assent where applicable. Starting in September 2024, we performed a method-comparison study in which both EAR and SBH were evaluated in subjects undergoing PCD evaluation, with each subject performing both techniques in the same testing session. nNO was measured using the EcoMedics CLD 88sp analyzer according to ATS/ERS standards. Clinical data included age, sex, genetic testing, ciliary biopsy, and PCD diagnosis. Linear regression and Bland-Altman analysis were used to assess correlation and agreement between EAR and SBH values. Results Forty-four subjects (24 males, 20 females; median age 10 years, range 4-25) underwent 56 paired nNO measurements, including eight with confirmed PCD. SBH and EAR were strongly correlated (R² = 0.94). Bland-Altman analysis showed minimal bias (−3%) and limits of agreement of − 22% to 16%, confirming reasonable agreement between the two methods. Conclusion In this cohort, the SBH maneuver demonstrated strong comparability to the EAR technique for nNO measurement, supporting its potential as a practical alternative for pediatric patients unable to perform EAR. Although nNO is a valuable screening tool, it is not a stand-alone diagnostic test and should be interpreted alongside clinical history, genetic testing, and ciliary electron microscopy. Further validation in larger cohorts is needed to confirm reproducibility, clinical utility, and establish standardized protocols. This abstract is funded by: none
Bergman-Sieger et al. (Fri,) studied this question.