Diagnostic value of lung ultrasonography in respiratory disorders of neonates

Abstract

Background Ionizing radiation-dependent modalities are still the mainstay investigations used in the neonatal intensive care unit (NICU). Neonates are particularly vulnerable to biohazards of ionizing radiation, a fact that renders searching for radiation-free modality a priority in the neonatal care setting.Patients and methods Patients who participated in this case–control study were classified into two groups: 127 neonates who presented to the NICU with respiratory distress manifestations were enrolled as the ‘case’ group, and 80 neonates 80 of comparable age and sex were selected and enrolled as the ‘control’ group, as they all had nonrespiratory manifestations. All participants were subjected to full history taking, thorough physical examinations, and routine investigations. Chest radiograph was performed on first presentation and as needed for follow-up as per the unit protocol; concomitantly, lung ultrasound (LUS) was performed with each radiograph. Throughout our study, if LUS interpretation in the context of clinical data reported the same diagnosis as clinical and radiography did, we considered the case as matching (positive) and vice versa.Results A total of 618 chest radiograph and concomitant LUS images were included in the study, as 207 (127 cases and 80 controls) images for initial diagnosis and 411 for follow-up of neonates presented with respiratory distress. The average number of images was 4.2 images/case during the follow-up (range, 1–22). Cases displayed lighter birth weight, with significantly higher prevalence of low birth weight and very low birth weight, than controls. Moreover, most cases (84%) were delivered by cesarean section. Among cases, transient tachypnea of newborn and respiratory distress syndrome were the most common diagnosis, whereas neonatal hyperbilirubinemia and seizures were the most frequent diagnosis among controls. Plain radiograph was the reference modality for diagnosis and follow-up (100% of cases had radiologic findings, whereas all controls had free chest radiograph). Overall, 8/127 (6%) cases of respiratory distress, clinically and radiologically, displayed normal LUS images at the initial presentation (false negative), whereas 3/80 (4%) of controls, who presented with nonrespiratory manifestations and had free chest radiograph, showed numerous B-lines on LUS (false positive). Nonsignificant differences were confirmed between chest radiograph findings and those of LUS in the initial diagnosis of different neonatal respiratory disorders, with sensitivity of 94%, specificity of 96%, positive predictive value of 97.5%, and negative predictive value of 90.5% for LUS as compared with plain chest radiograph. Similar matching between diagnosis concluded by radiographs and concomitant LUS was appreciated during follow-up of different respiratory diseases.Conclusion LUS is a suitable modality in NICU setting as it is a safe, radiation-free, dynamic, and real-time bedside assessment. It has an accepted validity in diagnosis and follow-up of different respiratory disorders in neonates with even higher abilities in detection of transient tachypnea of newborn, pleural effusion, and atelectasis.