Thoracic ultrasound accuracy for the investigation of initial neonatal respiratory distress

Thoracic ultrasound (TUS) is increasingly studied in neonatal respiratory distress but chest x-ray (CXR) remains the first-line exam. We aimed to evaluate its diagnostic performance for the investigation of unselected causes of neonatal respiratory distress in daily practice. We conducted a descriptive, prospective, and single-center diagnostic accuracy study in a tertiary hospital, including term and preterm newborns who needed a CXR because of respiratory conditions occurring at birth or during the first 24h of life. TUS was compared to the reference diagnosis, which was the association between the CXR results, the clinical initial context, and the patient's outcome. Fifty-two newborns were included and 104 hemi-thorax ultrasounds were analyzed. Sensitivity, specificity, positive and negative predictive values (PPV, NPV), diagnosis accuracy, as well as the positive and negative likelihood ratio of TUSs were 100% for respiratory distress syndrome (RDS), transient tachypnea of newborn (TTN), pneumomediastinum, meconium aspiration syndrome, and absence of pulmonary disease. TUS also showed 100% sensitivity and NPV for pneumothorax, but specificity was 97% and PPV was 50%. Kappa concordance between TUS and either CXR alone or the radiological/clinical gold standard was 0.79 and 0.95, respectively. TUS at the newborn's bedside is efficient for investigating the main neonatal respiratory diseases, especially for the confirmation of RDS or TTN and for the exclusion of differential diagnosis or complications.