Lung ultrasound score follows the chronic pulmonary insufficiency of prematurity trajectory in early infancy

Extremely preterm birth is associated with a high risk of chronic pulmonary insufficiency of prematurity (CPIP). Lung ultrasound score (LUS) proved capable to characterise CPIP progression beyond the acute setting, but still, post-discharge data remain lacking. We hypothesised a priori that LUS in both BPD and no-BPD infants declines with postnatal age from birth through early infancy. This observational retrospective cohort study included preterm infants < 32 gestational weeks, who underwent the follow-up for CPIP. LUS was assessed from birth to 8 months postnatal age, over antero-lateral (LUS) and posterior (pLUS) pulmonary areas, placing the transducer longitudinally over the midclavicular and midaxillary lines and medial to the scapular line respectively. Extended LUS (eLUS) including LUS and pLUS was calculated. The primary outcome was LUS time course. Secondary outcomes included the correlation between LUS and pLUS. Sixty-two infants were included: 22 (35.5%) in the BPD group and 40 (64.5%) in the no-BPD group. BPD group infants were smaller (weight 841 g (± 228) vs 1226 (± 328), p < 0.001) and younger (26.8 weeks (± 2.0) vs 28.9 (± 1.9), p < 0.001). LUS declined over time in the entire population (ß = − 1.75, p < 0.001) and in both no-BPD and BPD groups (ß = − 1.64, p < 0.001 and ß = − 1.93, p < 0.001, respectively). eLUS declined correspondingly (p < 0.001). LUS and likewise eLUS were significantly different between BPD and no-BPD groups over time (p < 0.001). Conclusion: LUS trajectory progressively decreased from birth to early infancy. BPD cohort tracked higher, implying a worse respiratory status. pLUS had a similar timepoint course, adding no further information to LUS. To the best of our knowledge, this is the first study that describes preterm LUS time course after discharge. LUS may help track the CPIP progression.What is Known:• Extremely preterm birth is associated with high risk of chronic pulmonary insufficiency of prematurity (CPIP).• Several studies investigated the ability of lung ultrasound score (LUS) to characterize CPIP progression beyond the acute setting, still post-discharge data remain lacking.What is New:• LUS trajectory progressively decreases from birth to early infancy; BPD cohort tracks higher, implying a worse respiratory status. pLUS has similar timepoint course, adding no further information to LUS.• The use of LUS may contribute to better characterising and monitoring CPIP in BPD and no-BPD infants.