Lung ultrasound in neonates under cardiac surgery: feasible and predictive

Purpose: To determine whether pre- and postoperative follow-up based on lung ultrasound is associated with the respiratory and clinical evolution of patients undergoing cardiac surgery in the neonatal period.

Methods: Prospective observational unicentric study from December 2020 to October 2023 in a neonatal intensive care unit, a referral center for congenital heart diseases (CHD). Neonates with CHD exposed to heart surgery or percutaneous catheterization in their first 28 days of life were included. LU follow-up was performed before surgery (LUSpre) and on days 1 (LUS_1), 3 (LUS_3), and 7 (LUS_7) afterwards by mean of a dedicated score (LUS) ranging from 0 to 3 points in 8 areas (total score 0-24).

Results: Fifty-five neonates were included. Median gestational age was 39.1 weeks (37.8-40.1), birth weight 3088 g (IQR 2910-3400). Forty-nine received surgery and 6 only percutaneous catheterization. Median LUSpre score was associated with total respiratory support in the first 30 postoperative days (p = 0.034). Median postoperative LUS was significantly higher than LUSpre in the surgery cohort at all time points (p < 0.05). LUS_1 was associated with respiratory and several clinical outcomes: for each point increase in the ultrasound score, the days on invasive mechanical ventilation, the need for any respiratory support within the first 30 postoperative days, and the length of NICU stay increased significantly (p < 0.05). The presence of consolidations in any area in the postoperative lung ultrasounds was associated with worse respiratory outcomes: higher invasive mechanical ventilation duration (6.84 days), longer total respiratory support (6.07 days), and NICU admission (21.61 days). The presence of consolidations in LUS_7 was significantly associated with the occurrence of ipsilateral diaphragmatic paralysis (odds ratio of 10.25 (95% CI 2.05-51.26, p = 0.006).

Conclusion: Performance of lung ultrasound follow-up in CHD in the NICU is feasible and predictive of the respiratory evolution of the patient. LUS_1 presented the highest predictive values. The presence of consolidations is associated with a worse respiratory evolution and if they persist for a week after the procedure, it may raise suspicion of ipsilateral diaphragmatic paralysis.