A retrospective analysis of tidal breathing pulmonary function characteristics in infants and young children with recurrent wheezing

Background Recurrent wheezing is common in infants and young children, but objective lung function assessment is limited because conventional spirometry is often not feasible. Tidal breathing pulmonary function testing may help characterize expiratory flow abnormalities in this age group. Objective To evaluate tidal breathing pulmonary function characteristics in infants and young children with recurrent wheezing. Methods This retrospective study included 178 children who underwent tidal breathing pulmonary function testing from March 2025 to March 2026, including 120 with recurrent wheezing and 58 non-wheezing controls. Core indices, abnormality patterns, multivariable logistic regression, sensitivity analyses, and exploratory ROC analysis were evaluated. Results Children with recurrent wheezing had a lower ratio of time to peak tidal expiratory flow to total expiratory time (tPTEF/tE) than non-wheezing controls, with a mean difference of −0.041 and P < 0.001. The ratio of volume to peak tidal expiratory flow to total expiratory volume (VPTEF/VE) was also lower in the recurrent wheezing group, with a mean difference of −0.045 and P < 0.001. Any tidal breathing pulmonary function abnormality was more frequent in the recurrent wheezing group than in controls, at 75.8% and 27.6%, respectively, P < 0.001. In a combined multivariable model including both core indices, higher tPTEF/tE and VPTEF/VE were independently associated with lower odds of recurrent wheezing, with adjusted ORs of 0.746 and 0.746 per 0.01 increase, respectively, both P < 0.001. Sensitivity analyses excluding premature infants, pneumonia cases, oxygen therapy, bronchodilator exposure, and lower-quality but analyzable tests showed consistent results. Exploratory ROC analysis showed moderate discriminatory ability, with AUCs of 0.779 for tPTEF/tE and 0.792 for VPTEF/VE. Conclusion Infants and young children with recurrent wheezing showed lower tPTEF/tE and VPTEF/VE, suggesting altered tidal expiratory breathing mechanics. These indices may provide supportive objective information for evaluating recurrent wheezing, but they should not be used as standalone diagnostic markers.