Regional lung function in congenital diaphragmatic hernia assessed using electrical impedance tomography

Congenital diaphragmatic hernia (CDH) is characterised by ventilation disunity due to unilateral pulmonary hypoplasia. We aimed to describe lung function in each of the ipsilateral (hypoplastic) and contralateral CDH lungs during neonatal intensive care unit (NICU) admission.

Prospective, observational study including infants with left-sided CDH. Electrical impedance tomography (EIT) images of both lungs were obtained over 20 min at three clinically distinct timepoints: pre-repair, post-repair and prior to NICU discharge. Centre of Ventilation (CoV, measure of regional distribution of tidal ventilation; <50% favours contralateral lung), aeration and time constants were calculated between the ipsilateral and contralateral lung.

Fifteen infants were included with median (range) gestational age 38 (34, 41) completed weeks, observed-to-expected lung-to-head ratio 51 (36, 67)% and 87% Type B or C lesion. Eight infants received high-frequency ventilation during admission. Ventilation was predominantly contralateral, with the ipsilateral lung ventilation increasing from pre-repair CoV 35 (31, 50)% to 42 (36, 49)% pre-discharge. Ipsilateral aeration was unchanged; 45 (38, 49)% of overall aeration pre-repair to 45 (33, 50)% pre-discharge. Time constants were 198 (143, 290) and 203 (141, 292) ms in the contra- and ipsilateral lung at discharge.

Lung function changes with time in CDH, and monitoring of each lung is possible using EIT.

Respiratory support of infants born with congenital diaphragmatic hernia (CDH) is challenging due to an inability to determine the magnitude of ventilation disunity resulting from unilateral pulmonary hypoplasia. Electrical impedance tomography (EIT) could describe the aeration and ventilation characteristics of the ipsi- and contra-lateral lungs throughout the NICU course in 15 infants with left-sided CDH. Ventilation, but not aeration, in the ipsilateral lung increased from the pre-repair state by discharge. This suggests EIT could be used to define lung function changes with time in CDH, providing a detailed understanding of each lung, which that may assist in refining care.