Preterm Infants’ Mortality Associated with BPD-PH

Around half of preterm infants develop bronchopulmonary dysplasia, a respiratory disease that can lead to long-term breathing and health problems. Around 20% of preterm newborns develop BPD with pulmonary hypertension, the condition’s most severe form.

An estimated 40% in this group will die before reaching the age of two. However, nothing is known about what causes BPD-PH to develop.

“Current screening methods are limited in their ability to detect BPD, let alone the severity of the disease,” said Samuel Gentle, M.D., assistant professor in the University of Alabama at Birmingham Division of Neonatology. “Since both BPD and BPD-PH are common morbidities in preterm infants, we wanted to evaluate other potential methods for earlier diagnosis.”

Gentle and colleagues from the University of Alabama at Birmingham’s Marnix E. Heersink School of Medicine conducted two studies to assess the risks and predictors of preterm infants having BPD-PH. The research’ findings, published in the American Journal of Respiratory and Critical Care Medicine, identify the duration of intermittent hypoxemia episodes and the length of time the patent ductus arteriosus channel stayed open as possible predictors of BPD-PH in preterm newborns.

BPD-PH with intermittent hypoxia

Preterm newborns have difficulty controlling their breathing because their lungs are undeveloped. This can result in intermittent hypoxemia, or decreases in an infant’s oxygen saturation level below a safe level on a regular basis.

According to research, the cumulative effect of IH episodes may be harmful to a neonate’s health. The first UAB study investigated whether IH episode features such as frequency and length of IH occurrences might predict which preterm infants will develop BPD-PH later in life.

Infants with IH bouts lasting more than one minute were twice as likely to develop BPD-PH, according to the findings. The frequency of the occurrences was the same in both groups.

“If the length of IH episodes is a predictor of developing of BPD-PH, it may enable physicians to identify infants with BPD-PH earlier on,” Gentle said. “We are hopeful that earlier detection translates to earlier intervention and improved outcomes in infants with this devastating disease.”

BPD-PH with patent ductus arteriosus

A fetus does not require blood to be pumped to its lungs when in utero because the mother delivers oxygen to the fetus. Instead, the patent ductus arteriosus channel is one mechanism by which blood from the heart is diverted away from the lungs and toward the body. The PDA vessel usually fades early in the transitional circulation period after a baby is delivered. Preterm newborns’ PDA vessels remain open for prolonged periods of time, perhaps months.

Gentle’s second study looked at how the time the PDA vessel was open affected the development of BPD-PH. The findings revealed that preterm infants delivered between 22 and 28 weeks with BPD-PH were more likely to have a PDA that remained open after 28 days. A chronic PDA duration was also linked to BPD-PH-related death. This was more common in infants with BPD alone.

Observational studies have revealed that babies with a PDA that is open for a longer period of time are more likely to develop BPD. Additional research has indicated that intervention, such as the administration of acetaminophen or ibuprofen, can help seal the PDA but does not always prevent the development of BPD.

“There is considerable practice variation as to whether doctors should intervene and close persistent PDAs,” Gentle said. “Our results provide evidence that taking a conservative approach to PDA intervention beyond four weeks after birth may increase infants’ risk of developing BPD-PH.”

Gentle also points out that it is unclear whether a persistent PDA causes BPD-PH or whether developing BPD-PH leads to a chronic PDA. He believes that longterm surveillance of PDA, including echocardiograms before 28 days postpartum, could reveal new markers that can be used as development determinants.

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