Semi-quantitative lung ultrasound score during ground transportation of outborn neonates with respiratory failure

Lung ultrasound score (LUS) is increasingly diffused in neonatal critical care but scanty data are available about its use during transfer of severely ill neonates. We aimed to clarify the effect of ground transportation on LUS evolution, conformity of interpretation, and relationships with oxygenation and clinical severity. This is a single-center, blinded, observational, cross-sectional study. Neonates of any gestational age with respiratory distress appearing within 24 h from birth were transferred by a mobile unit towards neonatal intensive care unit (NICU) of a tertiary referral center. Calculation of LUS prior to the transportation (T1), in the mobile unit (T2), at the end of transportation (T3), and finally upon NICU admission. LUS in the mobile unit and in the NICU was performed by different physicians blinded to each other's results. LUS did not change overtime (T1: 6.3 (3.5), T2: 6.1 (3.5), T3: 5.8 (3.4); p = 0.479; adjusted for gestational or postnatal age or transport duration: p = 0.951, p = 0.424, and 0.266, respectively) but reliably predicted surfactant need (AUC at T1: 0.833 (95%CI: 0.72-0.92); AUC at T2: 0.82 (95%CI: 0.70-0.91); AUC at T3: 0.82 (95%CI: 0.70-0.90); p always < 0.0001). There were significant agreement (ICC = 0.912 (95%CI: 0.83-0.95); p < 0.001) and correlation (r = 0.905, p < 0.001) between LUS calculated during transportation and in the NICU. LUS during transportation was also significantly correlated with oxygenation index (r = 0.321, p = 0.026; standardized B = 0.397 (95%CI: 0.03-0.76), p = 0.048) and TRIPS-II score (r = 0.302, p = 0.008; standardized B = 0.568 (95%CI: 0.04-1.1), p = 0.037).

Conclusion: LUS during ground transportation of neonates with respiratory failure is suitable and not influenced by the transportation itself. It has a high agreement with that calculated in the NICU and correlates with patients' oxygenation and severity.

What is known: • Lung ultrasound is a part of the point-of-care ultrasound, which is becoming an essential tool, to manage critically ill neonates and children in an accurate, non-invasive and quick way.

What is new: • Lung ultrasound score (LUS) is suitable during transportation of critically ill neonates with respiratory failure and is not influenced by the transportation itself. • LUS has a high agreement with that calculated in the NICU and correlates with patients' oxygenation and severity of respiratory failure.