Role of transabdominal ultrasound of lung bases and follow-up in premature neonates with respiratory distress soon after birth

Abstract

Background: Chest radiography has been the traditional method of diagnostic evaluation of patients of hyaline membrane disease (HMD). Lung sonography (USG) has been lately explored as an alternative modality.

Aims: To explore the application of transabdominal USG of lung bases (TASL) in the evaluation of HMD in premature neonates with respiratory distress soon after birth.

Settings and design: Tertiary care institutional setup. Study duration-18 months. Follow-up-variable, up to 1 month. Prospective descriptive study.

Materials and methods: Eighty-eight consecutive patients admitted in the neonatal intensive care unit (NICU) with gestational age <32 weeks having respiratory distress within 6 h of birth were enrolled. The diagnosis of HMD was made if the patient had negative gastric shake test and/or suggestive chest radiograph. TASL was performed in all patients within the first 24 h of life and biweekly subsequently. USG was interpreted as normal, HMD pattern, or broncho-pulmonary dysplasia (BPD) pattern. Biweekly follow-up was done for patients showing HMD till normalization of the sonographic HMD pattern, development of the sonographic BPD pattern, or death/discharge of the neonate from the hospital.

Results and conclusions: TASL showed 85.7% sensitivity, 75% specificity, 88.88% positive predictive value, and 69.2% negative predictive value for the diagnosis of HMD. The abnormal sonographic findings on day 14 had 94.1% accuracy for prediction of eventual occurrence of clinical BPD. TASL is complementary to chest radiograph in the diagnosis of HMD. It is also useful for the early prediction of BPD with the potential of reducing the cumulative radiation dose to these neonates.

Keywords: Hyperechogenicity; neonates; respiratory distress syndrome; transabdominal; ultrasound.

Figure 1(A-C)

TASL in newborn infants shows normal diaphragm echo (white arrow) complex-normal pattern (A), diffuse retrodiaphragmatic hyperechogenicity (white arrow) replacing the normal diaphragm echo complex-HMD pattern (B), and streaky retrodiaphragmatic hyperechogenicity (white arrow) replacing the normal diaphragm echo complex-BPD pattern (C)

Figure 2(A, B)

An 8-h-old boy born at 30 weeks of gestational age having respiratory distress soon after birth. Axial TASL (A) shows an HMD pattern. Chest radiograph (B) taken on day 1 was normal. Gastric shake test was negative. Respiratory distress was relieved within 24 h and final diagnosis of transient tachypnea of new-born was made

Figure 3(A-D)

A 6-hour-old girl born at 28+6 weeks of gestation having respiratory distress soon after birth. Axial TASL(A) ) shows an HMD pattern. Corresponding chest radiograph (B) taken on day 1 showed bilateral whiteout lungs consistent with hyaline membrane disease. Coronal TASL (C) at day 14 showed resolution of HMD pattern with corresponding chest radiograph (D) showing normalization (Group 2)

Figure 4(A-D)

A 10-hour-old newborn boy born at 28+3 weeks of gestation having respiratory distress at birth. Coronal TASL (A) shows an HMD pattern. Corresponding chest radiograph (B) taken on day 1 shows low volume lungs with granular opacities and few central air-bronchograms. Coronal TASL (C) at day 11 shows transformation to BPD pattern with corresponding chest radiograph (D) (Group 3). Child was diagnosed as BPD on day 28 of life