Can neonatal lung ultrasound monitor fluid clearance and predict the need of respiratory support?

Introduction: At birth, lung fluid is rapidly cleared to allow gas exchange. As pulmonary sonography discriminates between liquid and air content, we have used it to monitor extrauterine fluid clearance and respiratory adaptation in term and late preterm neonates. Ultrasound data were also related to the need for respiratory support.

Methods: Consecutive infants at 60 to 120 minutes after birth underwent lung echography. Images were classified using a standardized protocol of adult emergency medicine with minor modifications. Neonates were assigned to type 1 (white lung image), type 2 (prevalence of comet-tail artifacts or B-lines) or type 3 profiles (prevalence of horizontal or A lines). Scans were repeated at 12, 24 and 36 hours. The primary endpoint was the number of infants admitted to the neonatal ICU (NICU) by attending staff who were unaware of the ultrasound. Mode of respiratory support was also recorded.

Results: A total of 154 infants were enrolled in the study. Fourteen neonates were assigned to the type 1, 46 to the type 2 and 94 to the type 3 profile. Within 36 hours there was a gradual shift from types 1 and 2 to type 3. All 14 type 1 and 4 type 2 neonates were admitted to the NICU. Sensitivity was 77.7%, specificity was 100%, positive predictive value was 100%, negative predictive value was 97%. Four type 1 infants were mechanically ventilated.

Conclusions: In the late preterm and term neonate, the lung ultrasound scan follows a reproducible pattern that parallels the respiratory status and can be used as a predictor of respiratory support.