Preterm babies’ survival raised with inhaled nitric oxide rapid response

6 studies covering 400 infants were included in a meta-analysis by researchers

Patricia Inácio, PhD avatar

by Patricia Inácio, PhD |

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Inhaled nitric oxide (iNO) therapy reduces the risk of death in preterm infants with severe hypoxemic respiratory failure (HRF) — low oxygen in the blood — and suspected or confirmed pulmonary hypertension (PH), a study shows.

“The findings provide evidence supporting the prognostic value of oxygenation response and support the clinical practice and current guidelines to consider a trial of iNO therapy in preterm infants with HRF where PH is the underlying pathophysiology [disease cause], either proven or suspected,” the researchers wrote.

The study, “Association Between Immediate Oxygenation Response and Survival in Preterm Infants Receiving Rescue Inhaled Nitric Oxide Therapy for Hypoxemia from Pulmonary Hypertension: A Systematic Review and Meta-analysis,” was published in Early Human Development.

At birth, a baby’s lungs start to expand with the first breaths of air, as the umbilical cord is clamped and the baby no longer receives oxygen from the mother.

iNO, a vasodilator gas, is routinely used off-label as a first-line treatment for babies with HRF. It works by relaxing and widening blood vessels, which lowers blood pressure.

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Treating HRF in infants with inhaled nitric oxide

In developed countries, the use of iNO has become more common as an immediate treatment for HRF in preterm infants with PH, but few studies have assessed its effectiveness, leading an an international team of researchers to investigate whether immediate response to iNO is associated with lower mortality among preterm infants with severe HRF and suspected or confirmed PH. Immediate response to iNO is defined as improved oxygen in the blood within six hours of treatment. Suspicion of PH is based on clinical assessment, whereas confirmation is made with an echocardiography or an assessment of oxygen in the blood.

The scientists conducted a systematic review and meta-analysis of studies published up to last February across five databases. The ones that were included reported on the use of iNO in preterm infants born before they completed 34 weeks of gestational age, which is how far along in weeks a pregnancy has advanced since the mother’s last menstrual period. A meta-analysis is an analysis that combines the results of multiple scientific studies.

Six studies covering 400 infants — 196 responders to iNO and 204 nonresponders — were included. All were published in the last six years.

Results showed that immediate response to iNO was associated with a reduced risk of infant mortality, including in infants who received iNO therapy within the first 72 hours (three days) after birth.

No analysis was conducted for infants with preterm premature rupture of membranes (PPROM) due to a lack of data and inconsistencies in defining PPROM across the studies. PPROM occurs when the amniotic sac surrounding the baby breaks before the 37th week of pregnancy.

The findings suggest “immediate improvement in oxygenation following iNO therapy is associated with reduced odds of mortality before [hospital] discharge in preterm infants with HRF and clinically suspected or confirmed PH.”

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