Materials and Methods
Patients :
This prospective cohort study was conducted at the neonatal intensive care unit of Kasr El Aini Hospital, a referral tertiary care university hospital. The study was approved by the Institutional Research Ethics Board and informed parental consents were obtained for all subjects before recruitment. Infants were included in the study if they fulfilled the following criteria: a) gestational age <34 weeks, b) postnatal age <48 hours, and c) supported with invasive mechanical ventilation for initial presentation with RDS. Infants were excluded if they were extubated before 3 days of life or if they had any of the following: a) major congenital anomalies, b) perinatal asphyxia, or c) hemodynamic instability managed by inotropic administration at the time of screening.
Demographic and clinical data were collected from the chart. Those data included the use of antenatal steroids, infant’s sex, gestational age (GA), birth weight (BW), small for gestational age status, Apgar scores at 5 and 10 minutes, perinatal confirmed infections, and intraventricular hemorrhage. Clinical parameters of hemodynamic stability including systolic and diastolic blood pressures, heart rate, urine output, and lactic acid at the time of assessment were collected. Data on respiratory outcomes were collected; bronchopulmonary dysplasia (BPD) was defined by the use of respiratory support or supplemental oxygen to maintain oxygen saturation >90 by pulse oximeter at 36 weeks of postmenstrual age for infants born ≤ 32 weeks of gestation and the use of supplemental O2 at 28 days for infants born at 33-34 weeks of gestation 10.
LUS and transthoracic focused cardiac ultrasound (FCUS) were performed on postnatal days 3 and 7 for all recruited infants. The radiologist who performed the studies (R.H.) was masked to the clinical details of infants; likewise, the managing team was blinded to the ultrasound results. If an infant was extubated after 3 days and before 7 days, he/she would have only one study at 3 days of life.