Tidal Breathing Measurements in Former Preterm Infants : A Retrospective Longitudinal Study

Objectives: To investigate, in infants born preterm with or without bronchopulmonary dysplasia (BPD), the trajectory of tidal breathing flow-volume (TBFV) parameters in the first 2 years of life; the association between TBFV parameters and perinatal risk factors; and the predictive value of TBFV parameters for rehospitalizations due to respiratory infections and wheeze. Study design: We retrospectively analyzed TBFV measurements performed at 0-6, 6-12, and 12-24 months of corrected age in 97 infants <32 weeks of gestation and <1500 g. We assessed the association between TBFV parameters and perinatal risk-factors using linear regressions and the predictive capacity for subsequent respiratory morbidity using logistic regressions. We used the area under the curve and likelihood ratio test (LRT) to compare nested models. Results: Time to peak tidal expiratory flow/expiratory time ratio (tPTEF/tE) was lower than normal for the first 2 years of corrected age. Longer duration of oxygen supplementation, intubation, and respiratory support were associated with reduced tPTEF/tE at all time points. For each z-score increase in tPTEF/tE, the OR for rehospitalizations decreased by 0.70. tPTEF/tE added significantly to BPD classifications alone in predicting rehospitalizations (area under the receiver operating characteristic curve = 0.81 vs 0.76, P value for LRT = .0012), and wheeze (area under the receiver operating characteristic curve = 0.76 vs 0.71, P value for LRT <.001). Conclusions: Infants born preterm, with and without BPD, display persistent airway obstruction during the first 2 years of life. tPTEF/tE may identify infants at greater risk of severe respiratory morbidity.