[Lung Ultrasonography for the Diagnosis of Neonatal Respiratory Distress Syndrome: a Pilot Study]

Objective: The diagnosis of respiratory distress syndrome (RDS) is usually based on clinical manifestations, arterial blood gas analysis and chest x-ray. Lung ultrasounds are typically not included in the diagnostic work-up of neonatal RDS. Recently, ultrasounds have been used extensively and successfully in the diagnosis of many kinds of lung diseases, but few studies have addressed neonatal RDS. This study aimed to evaluate the value of lung ultrasound in the diagnosis of neonatal RDS.

Method: From May, 2012 to September, 2012, 45 newborn infants with RDS and 30 neonates without lung disease were enrolled into this study. Lung ultrasound was performed at bedside by a single expert physician in the first 24 h of life before exogenous pulmonary surfactant administration. The transthoracic approach was performed with longitudinal scans of the anterior, lateral and posterior chest walls. A conventional antero-posterior chest X rag was performed at bedside in the patients immediately when lung ultrasound was finished.

Result: The ultrasound signs of lung consolidation, pleural line abnormalities, bilateral "white lung" and A-line disappearance were seen in 100% of RDS patients while they were not found in any of the controls (P < 0.001). Lung pulse was 80% in RDS patients and in 0% of controls, respectively (P = 0.001). The pleural effusion were 13.3% in RDS patients and 0% in controls, respectively (P < 0.001). B-lines existed in 4.4% of RDS patients and in 26.7% of controls (P = 0.012). Both the sensitivity and specificity were 100% when ultrasonic signs of lung consolidation, pleural line abnormalities and bilateral "white lung" coexisted or when lung consolidation, pleural line abnormalities and A-line disappearance coexisted. The presence of lung pulse demonstrated a sensitivity of 80% and a specificity of 100% in diagnosis of RDS.

Conclusion: The main ultrasound imaging features of neonatal RDS include lung consolidation with air bronchograms, pleural line abnormalities, lung pulse and bilateral "white lung" or alveolar-interstitial syndrome. It is accurate and reliable that using ultrasound to diagnose neonatal RDS, which also has many other advantages including non-ionizing, can be performed at bedside, easy-operatinng, can be repeated several times in a day without hazards to the operators and the patients. Therefore, it deserves to be carried out in the neonatal ward.