The association between pulmonary vascular disease and respiratory improvement in infants with type I severe bronchopulmonary dysplasia.

Objective: To describe the association between echocardiographic measures of pulmonary vascular disease and time to respiratory improvement among infants with Type I severe bronchopulmonary dysplasia (sBPD).

Study Design: We measured the pulmonary artery acceleration time indexed to the right ventricular ejection time (PAAT/RVET) and right ventricular free wall longitudinal strain (RVFWLS) at 34-41 weeks' postmenstrual age. Cox-proportional hazards models were used to estimate the relationship between the PAAT/RVET, RVFWLS, and the outcome: days from 36 weeks' postmenstrual age to room-air or discharge with oxygen (≤0.