Lung ultrasound score parallels trends in systemic haemodynamics after PDA ligation: a case series

Abstract

B-lines in lung ultrasound (LU) are non-specific but highly informative sign of interstitial pulmonary oedema (iPE). Sustained exposure to a high-volume left-to-right patent ductus arteriosus (PDA) shunt is associated with iPE. Cardiorespiratory deterioration, named post-ligation cardiac syndrome (PLCS), may follow surgical ligation between 6 and 12 h post-operatively. We conducted a pilot longitudinal evaluation of peri-procedural LU score change. Infants < 32-week gestational age or < 1500-g birthweight undergoing PDA ligation, where pre-, 1 h and 6-12 h LU were performed, were included. Two independent raters evaluated LU score (LUS). Neonatologist performed echocardiography (NPE) was performed concurrently to appraise changes in left ventricular output (LVO). Milrinone was initiated if LVO was < 200 mL/kg/min 1 h after surgery, to prevent PLCS. The primary outcome was peri-procedural LUS change. Secondary outcomes included PLCS. Five infants were included (birthweight 787(88) g; gestational age 25.6(0.7) weeks). Postnatal age and weight at the intervention were 41(14) days and 1175(295) g. All infants, but one, received milrinone prophylaxis. None of the patients developed PLCS or required rescue HFOV. Post-interventional LUS were lower compared to pre-operative LUS (p = 0.041 vs 1 h, p = 0.042 vs 6-12 h). A concurrent fall post-operative LVO was noted (p < 0.05 vs pre-operative).

Conclusion: A sustained fall in LUS after PDA ligation was identified, which most likely reflects reduction in pulmonary blood flow and interstitial edema. Changes in LUS paralleled changes in LVO, suggesting physiologic linkage. These data suggest that LU may be a useful tool to guide monitoring the biologic nature of pulmonary disease after PDA ligation.

What is known: • Sustained exposure to a high-volume left-to-right patent ductus arteriosus (PDA) shunt is associated with interstitial pulmonary oedema. • In the most immature patients, cardiorespiratory deterioration, named post-ligation cardiac syndrome, presents 6-12 h post-operatively.

What is new: • An early and sustained fall in lung ultrasound score (LUS) after PDA ligation most likely reflects reduction in pulmonary blood flow and interstitial oedema. LUS changes parallel changes in left ventricular output, suggesting linkage. • LU is a promising adjunctive tool in the post-operative management of PDA ligation.

Keywords: Lung ultrasound; Neonatologist-performed echocardiography; PDA ligation; Patent ductus arteriosus; Post-ligation cardiac syndrome; Pulmonary oedema.