To study the pulmonary ultrasonic manifestations in neonatal respiratory distress syndrome (NRDS), and to explore the value of pulmonary ultrasound on disease assessment and diagnosis of NRDS.

From January 2015 to December 2016, a total of 69 preterm infants with NRDS who were hospitalized in Chengdu Women′s & Children′s Central Hospital, and 55 preterm infants without pulmonary diseases who were hospitalized during the same period in the same hospital were chosen as research subjects, and they were enrolled into NRDS group and control group, respectively. All preterm infants were examined for pulmonary ultrasound before treatment, and preterm infants in NRDS group were re-examined with pulmonary ultrasound at 72 h after treatment. The characteristics of pulmonary ultrasound imaging of preterm infants in NRDS group were summarized and analyzed. Fisher′s exact test was used to compare the results of pulmonary ultrasound before treatment between two groups. The paired-chi-square test was used to compare the pulmonary ultrasound results of preterm infants in NRDS group between before treatment and 72 h after treatment. There were no statistical differences between two groups in the gender ratio, gestational age, birth weight and so on (P>0.05). This study was approved by the Ethics Committee of Chengdu Women′s & Children′s Central Hospital (Approval No. 2014 [5]), and all guardians of preterm infants signed the informed consents.

①The pulmonary ultrasonic manifestations of preterm infants in NRDS group mainly included pulmonary consolidation, abnormal pleura lines, A-line disappearance, pleural effusion, white lung and lung pulsation. The pulmonary ultrasound results showed that the range of pulmonary consolidation was gradually narrowing down, air bronchogram was relieved, pleura lines returned to normal and A-line appeared gradually with the improvement of NRDS preterm infants′ conditions. ②The incidence rates of pulmonary consolidation, abnormal pleural lines, A-line disappearance, pleural effusion, white lung and lung pulsation of preterm infants in NRDS group were 100.0% (69/69), 100.0% (69/69), 100.0% (69/69), 14.5% (10/69), 91.3% (63/69) and 76.8% (53/69), respectively, which were significantly higher than those of 0 (0/55), 0 (0/55), 0 (0/55), 5.5% (3/55), 0 (0/55), 9.1% (5/55), respectively in control group, and all the differences were statistically significant (all P<0.001). There was no significant difference between two groups in the ratio of B-line existence (P>0.05). ③In NRDS group, the incidence rates of pulmonary consolidation, abnormal pleural lines, A-line disappearance, white lung and lung pulsation of preterm infants at 72 h after treatment were 40.6% (28/69), 36.2% (25/69), 26.1% (18/69), 17.4% (12/69) and 20.3% (14/69), respectively, which were significantly lower than those before treatment, while the ratio of B-line existence (30.4%, 21/69) was significantly higher than that of 13.0% (9/69) before treatment, and these differences were statistically significant (χ²=39.024, 42.023, 49.020, 49.020, 37.026, 10.083; all P<0.001). There was no significant difference between before treatment and 72 h after treatment in the incidence rate of pleural effusion (P>0.05).

Pulmonary ultrasonic manifestations of preterm infants with NRDS can reflect their conditions. And there are advantages of timeliness, non-invasiveness, repeatability and without space limitation of pulmonary ultrasound on assesment of lung conditions of preterm infants with NRDS.