Three-dimensional ultrasound fetal lung volumes and infant respiratory outcome: a prospective observational study

OBJECTIVE: To determine if fetal lung volumes (FLVs), determined by three-dimensional rotational ultrasound and virtual organ computer-aided analysis software (vocal), correlated with neonatal respiratory outcomes in surviving infants who had a high risk [fetuses with congenital diaphragmatic hernia (CDH)], lower risk [fetuses with anterior wall defects (AWDs)] and no risk (controls) of abnormal antenatal lung growth. DESIGN: Prospective observational study. SETTING: Tertiary fetal medicine and neonatal intensive care units. POPULATION: Sixty fetuses (25 with CDH, 25 with AWDs and ten controls). METHODS: FLVs were measured and expressed as the percentage of the observed compared with the expected for gestational age. MAIN OUTCOME MEASURES: Neonatal respiratory outcome was determined by the duration of supplemental oxygen, mechanical ventilation and dependencies, and assessment of lung volume using a gas dilution technique to measure functional residual capacity (FRC). RESULTS: The infants with CDH had lower FLV results than both the infants with AWDs (P=0.05) and the controls (P<0.05). The infants with CDH had longer durations of mechanical ventilation (P<0.001) and supplementary oxygen (P<0.001) dependence, compared with infants with AWDs. The infants with CDH had a lower median FRC than both the infants with AWDs (P<0.001) and the controls (P<0.001). FLV results correlated significantly with the durations of dependency on ventilation (r= -0.744, P<0.01) and oxygen (r= -0.788, P<0.001), and with FRC results (r=0.429, P=0.001). CONCLUSIONS: These results suggest that FLVs obtained using three-dimensional rotational ultrasound might be useful in predicting neonatal respiratory outcome in surviving infants who had varying risks of abnormal lung growth. Larger and more comprehensive studies are needed to clarify the role that lung volume measurements have in assessing lung function and growth.