Causes and Consequences of Bronchopulmonary Dysplasia

Sullivan K, et al. The Association between Positive Tracheal Aspirate Cultures and Adverse Pulmonary Outcomes in Preterm Infants with Severe Bronchopulmonary Dysplasia. American journal of perinatology. 2016(EFirst).  This is an interesting study, with many limitations. 121 intubated VLBW preterm infants who had at least one Endotracheal bacterial culture are included. Outcomes of the babies and relationship with the results of the cultures were studied. The cultures were not performed as a routine, but whenever the treating team felt that they needed one. Which is the first problem with the study, we don’t know why the team wanted to have an endotracheal culture. 80% of the cultures were positive for potential pathogens, 30% had more than one. 30% had Pseudomonas and another 14% Klebsiella. Babies who had Gram negative rods in the cultures were more likely to have the adverse outcome, which was death or going home on oxygen.  Babies who had gram positive cocci in the cultures, in contrast, were not more likely to have severe BPD or death.

Previous data has shown a correlation between Ureaplasma cultures and BPD, but I don’t think there are many data about other bacteria in the endotracheal tube. In order to know whether these data are really showing a causative relationship, I think you would need firstly a study with all intubated babies having routine cultures at the same postnatal age, and then redo this sort of analysis. Then a randomized trial of treating the positive cultures with effective antibiotics would be needed to confirm that any association may be causative, and that you can do something about it.

Sanchez-Solis M, et al. Lung function gain in preterm infants with and without bronchopulmonary dysplasia. Pediatr Pulmonol. 2016. 71 VLBW infants were studied at 6 months corrected age, and again a year later. The VLBW babies with BPD had significantly lower FVC and FEF25-75 (an indicator of small airways function). When they restudied them, the trajectory of changes in both groups was similar, as they babies length increased, the lungs grew, but the differences between the BPD and non-BPD groups remained about the same; there was no catch-up in lung function.

Poon CY, et al. Pulmonary arterial response to hypoxia in survivors of chronic lung disease of prematurity. Archives of Disease in Childhood – Fetal and Neonatal Edition. 2016;101(4):F309-F13. In this study the pulmonary vascular reactivity to 12% oxygen inhalation (compared to 21%) of former preterm infants with and without BPD and controls was examined, there were 13 with BPD, 21 preterm without BPD, and 25 term born children examined at 9 to 12 years of age.

The technique that was used is completely new to me, using MRI, they measured the cross-sectional area of the pulmonary artery and the blood flow through the measured segment. They plot the changes in the 2 measurements during early systole,  and the slope of the regression is referred to as the pulse wave velocity (PWV). They then redo the PWV after exposing the children to hypoxia. Normal children, previously studied by this group have an increase in PWV with hypoxia. In this study the preterm born children with BPD had a greater increase in their PWV than the controls. The children were all healthy, but still have what appears to be an increase in pulmonary vascular reactivity (assuming that this technique is indeed reliable), even 10 years later.

Van Hus JWP, et al. Early intervention leads to long-term developmental improvements in very preterm infants, especially infants with bronchopulmonary dysplasia. Acta Paediatrica. 2016;105(7):773-81. This is a report of an RCT in a 176 infants who were either VLBW or less than 32 weeks. Infants were either enrolled in an Early Infant Behaviour and Intervention Program. and then followed at 6, 12 and 24 months with Bayley version 2, and at 5.5 years with the WPPSI IQ test and the Movement Assessment Battery for Children. Overall the motor scores were better in the group with the early intervention, and remained so throughout the follow up, The cognitive scores were a bit better with early intervention, but that may have been due to chance (“not significant”). In a subgroup analysis, of just the babies with BPD, both cognitive scores and motor function was improved with early intervention.

About Keith Barrington

I am a neonatologist and clinical researcher at Sainte Justine University Health Center in Montréal
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