Lung ultrasound score (LUS) is an effective means of predicting whether extremely preterm neonates undergoing continuous positive airway pressure (CPAP) treatment for respiratory distress syndrome (RDS) require surfactant, according to results of study published in Pediatrics.
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Lucia De Martino, MD, of the division of pediatrics and neonatal critical care at the A. Béclère Medical Centre of the South Paris University Hospital and her associates enrolled 133 neonates of 30 weeks’ gestation or less born between 2015 and 2016. They designed the prospective diagnostic accuracy cohort study, which was conducted in an academic tertiary care referral neonatal ICU.
The first dose of surfactant was administered at a mean 4 hours of life. Those that required further treatment received a second dose of surfactant at a mean 28 hours of life. Each patient received a single lung ultrasound lasting an average of 3 minutes. In each case, the procedure was well tolerated.
In particular, the study demonstrated that LUS is able to accurately predict the need for a first dose and “reveals fair accuracy when it comes to predicting surfactant retreatment,” they observed. The authors speculate that using LUS to predict retreatment is somewhat less reliable because of either the lower number of patients requiring retreatment or reasons related to the biology of surfactant.
“A LUS cutoff value between 6 and 8 provides optimal sensitivity and specificity for predicting the need for the first surfactant dose, whereas a cutoff value of 10 predicts the need for surfactant retreatment,” Dr. De Martino and her colleagues advised.
Of key importance was the finding that LUS is of greatest value to preterm infants less than 34 weeks’ gestation; the authors observed that LUS had significantly lower diagnostic accuracy in infants who were either late term or term. They offered that this outcome was likely attributable to the homogeneous nature of preterm neonates, who are commonly affected by RDS and tend to present with a variety of respiratory disorders and surfactant injury to differing degrees.
At present, international guidelines only recommend surfactant replacement in cases where CPAP has failed, but administering surfactant within the first 2-3 hours of life is key to reducing bronchopulmonary dysplasia as well as the risk of death, they said.
Current surfactant replacement is determined solely by fraction of inspired oxygen cutoff levels, which can result in delayed or even unnecessary treatment. Because neonates who are extremely preterm benefit the most from treatment, “both situations are potentially harmful because late surfactant replacement is less efficacious and giving surfactant when it is not needed may be invasive and seems to increase lung inflammation in animal models,” Dr. De Martino and her associates cautioned.
The authors had no relevant financial disclosures.
SOURCE: De Martino L et al. Pediatrics. 2018. doi: 10.1542/peds.2018-0463.