Pulmonary Function Testing using Tidal Breath Flow-Volume Loops in Healthy Children 1-24 months of age in semi-rural Nepal: Feasibility Study

Background and objective: Early-life insults affect lung function trajectories throughout life. In Nepal there is a high burden of disease from lower respiratory tract infections, and high levels of exposures to household and environmental pollution. To enable assessment of these factors on lung development we aimed to assess the feasibility of establishing a pulmonary function laboratory for tidal breath flow-volume loops (TBFVL) in infants and children in Dhulikhel, Nepal. Methods: A pulmonary function laboratory was established and TBFVL testing, meeting international quality standards, were performed on healthy children 1-24 months of age, between October 2024 and May 2025, in Dhulikhel, Nepal. Results were interpreted by local staff after initial training and ongoing oversight by international experts. TBFVL indices with coefficient of variation (CoV) were reported and inter-interpreter level of agreement evaluated using Bland-Altman plots. Results: Eighty-six children were included, of which 80 (93%) had successful tests. Fifty-five (69%) 0-<4 months, 12 (15%) 4-<12 months and 13 (16%) 12-24 months of age. The CoV ranged from 4.7 (4.4, 5,2) for tidal volume to 19.5 (15.8, 24.1) for the ratio of the proportion of time to reach peak tidal expiratory flow to total expiratory time (T _PTEF /TE), with CoV being similar across age groups. Agreement between local and expert international assessors was good, with the largest mean inter-interpreter difference observed for T _PTEF /TE. Conclusion: Establishing a pulmonary function laboratory and achieving high-quality TBFVL measurements with expert-level interpretation is feasible in Nepal and contributes to the knowledge of normal pulmonary function values in Nepali children.