A recent study published in BMC Pediatrics shows that reliable, objective, early criteria for inhaled nitric oxide (iNO) treatment response in newborns with hypoxic respiratory failure (HRF) still needs to be established.
An estimated two percent of babies born in the U.S. are thought to need help breathing using machines. About 35,000 of these babies need assistance because of HRF — a condition in which blood oxygen levels are low and oxygen therapy is ineffective. Persistent pulmonary hypertension of the newborn (PPHN) is a common cause of respiratory failure in newborns.
HRF can be successfully treated in many newborns by inhaled nitric oxide (iNO) — a gas that helps the blood vessels in the lungs relax and widen — which can improve blood oxygen levels. Some newborns who do not respond to iNO require more advanced HRF treatment, including the need for extracorporeal membrane oxygenation (ECMO) — an invasive treatment that bypasses the heart and/or lungs of a baby to circulate blood and provide oxygen. Doctors are interested in learning whether they can improve their prediction of which newborns will require the more advanced HRF treatments like ECMO.
The study authors reviewed data collected during the Clinical Inhaled Nitric Oxide Research Group Investigation (CINRGI) published in 2000. They specifically wanted to learn whether responding to iNO quickly (within one hour) would predict which newborns would require ECMO. Many newborns in the CINRGI study were labeled “non-responders” when they did not have improved oxygen levels within one hour of iNO treatment. While most newborns (52 percent) showed improvement in oxygenation, and most showed this improvement within the first hour of treatment and were labeled treatment “responders,” nearly 20 percent had improved oxygen levels after the first hour of iNO treatment.
The study authors also showed that of the newborns who required ECMO treatment, and were thus ultimately labeled “non-responders,” 83 percent had an initial improvement to iNO treatment.
The analysis of the data suggests that simply looking at initial oxygenation improvement after iNO treatment is not a way to precisely identify full treatment “response,” and, thus, which newborns require ECMO. The CINRGI study shows a positive effect of iNO treatment on improving outcomes in newborns with PPHN and HRF, but response to iNO treatment within one hour is not a clear, objective cutoff to determine treatment responders vs. non-responders.
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