INTRODUCTION
Lung ultrasound (LU) is proving very useful in Neonatal Intensive Care Units (NICU): it is diagnostic for respiratory diseases with a higher accuracy than X-ray 1–3, predicts the need for admission of neonatal patients 4, non-invasive ventilation failure 5,6, or even the need for surfactant in preterm 7 and very low birth weight infants 8. It also predicts bronchopulmonary dysplasia (BPD) in very low birth weight infants in the first week of life9,10. Therefore, it is a harmless, and easy to learn technique, rendering high intraobserver and interobserver agreement11. For all these reasons, it is becoming widely extended in NICUs around the world.
LU score is a semiquantitative value that correlates well with the oxygenation status of neonatal patients 7, and the severity of respiratory diseases 12. It can be used to monitor progression of lung diseases, and to compare LUs in the same patient. LU detects pulmonary edema better than X-ray13, and it is helpful to evaluate lung edema in neonates, according to the guidelines on Point of Care Ultrasound for critically ill neonates and children by the European Society of Paediatric and Neonatal Intensive Care 14. LU score is a real time indicator of extravascular lung water 15, and it also correlates with lung inflammation in preterm neonates16. On the other hand, LU scores remain high since birth until 36 weeks’ postmenstrual age (PMA) in very low birth weight infants with BPD 10.
Diuretics are often prescribed in preterm infants with established BPD, although there is little evidence to support their long-term efficacy and safety 17. Different studies have demonstrated that furosemide may improve respiratory function in preterm infants, due to fluid removal from lung tissue 18–20. Anyway, some studies in BPD patients have failed to show real benefits in these subgroup of preterm infants 21,22, but a more recent one shows a decrease in BPD or death in preterm infants on furosemide23. On the other hand, secondary effects due to their long-term use have been described in terms of decreased bone mineralization, hearing loss or nephrotoxicity.
Therefore, we conducted a study with the aim to describe if weekly determined LU scores in preterm infants born before 32 weeks (PTB32W) change with diuretic therapy.