Echocardiographic Measurements of Right Ventricular Mechanics in Infants with Bronchopulmonary Dysplasia at 36 Weeks Postmenstrual Age.

OBJECTIVE: To test the hypothesis that specific echocardiographic measurements of right ventricular (RV) mechanics at 36 weeks postmenstrual age (PMA) are associated with the severity of bronchopulmonary dysplasia (BPD). STUDY DESIGN: A subset of 93 preterm infants (born between 27 and 29 weeks of gestation) was selected retrospectively from a prospectively enrolled cohort. BPD was defined using the National Institutes of Health workshop definition, with modifications for oxygen reduction testing and altitude. The cohort was divided into no-BPD and BPD groups using previously published methodology for analyses. Echocardiographic measurements of RV function (ie, tricuspid annular plane systolic excursion, fractional area of change, systolic-to-diastolic ratio, tissue Doppler myocardial performance index, and RV strain), RV remodeling/morphology (end-systolic left ventricular eccentricity index), and RV afterload (pulmonary artery acceleration time measure) were evaluated at 36 weeks PMA. Multivariable logistic regression determined associations between RV measurements and BPD severity. RESULTS: Compared with the no-BPD cohort, the BPD group had lower birth weight z-scores (P = .04) and trended toward a male predominance (P = .08). After adjusting for birth weight z-score, gestational age, and sex, there were no between-group differences in echocardiographic measurements except for the eccentricity index (scaled OR [0.1-unit increase], 1.49; 95% CI, 1.13-2.12; P = .01). CONCLUSIONS: Among conventional and emerging echocardiographic measurements of RV mechanics, eccentricity index was the sole variable independently associated with BPD severity in this study. The eccentricity index may be a useful echocardiographic measurement for characterizing RV mechanics in patients with BPD at 36 weeks PMA.

Antenatal Determinants of Bronchopulmonary Dysplasia and Late Respiratory Disease in Preterm Infants.

RATIONALE: Mechanisms contributing to chronic lung disease after preterm birth are incompletely understood. OBJECTIVES: To identify antenatal risk factors associated with increased risk for bronchopulmonary dysplasia (BPD) and respiratory disease during early childhood after preterm birth, we performed a prospective, longitudinal study of 587 preterm infants with gestational age less than 34 weeks and birth weights between 500 and 1,250 g. METHODS: Data collected included perinatal information and assessments during the neonatal intensive care unit admission and longitudinal follow-up by questionnaire until 2 years of age. MEASUREMENTS AND MAIN RESULTS: After adjusting for covariates, we found that maternal smoking prior to preterm birth increased the odds of having an infant with BPD by twofold (P = 0.02). Maternal smoking was associated with prolonged mechanical ventilation and respiratory support during the neonatal intensive care unit admission. Preexisting hypertension was associated with a twofold (P = 0.04) increase in odds for BPD. Lower gestational age and birth weight z-scores were associated with BPD. Preterm infants who were exposed to maternal smoking had higher rates of late respiratory disease during childhood. Twenty-two percent of infants diagnosed with BPD and 34% of preterm infants without BPD had no clinical signs of late respiratory disease during early childhood. CONCLUSIONS: We conclude that maternal smoking and hypertension increase the odds for developing BPD after preterm birth, and that maternal smoking is strongly associated with increased odds for late respiratory morbidities during early childhood. These findings suggest that in addition to the BPD diagnosis at 36 weeks, other factors modulate late respiratory outcomes during childhood. We speculate that measures to reduce maternal smoking not only will lower the risk for preterm birth but also will improve late respiratory morbidities after preterm birth.