Evolution of diaphragmatic thickness and function in preterm infants on non-invasive neurally adjusted ventilatory assist

Abstract Purpose Non-invasive neurally adjusted ventilatory assist (NIV-NAVA) is respiratory support that is synchronized with the electrical activity of the diaphragm (Edi) and uses the Edi to proportionally assist breathing by unloading the diaphragm. The aim of the study was to evaluate the effect of this diaphragm-triggered ventilation on the diaphragmatic structure and function . Methods This observational cohort study aimed to track changes in diaphragm thickness (DT), measured with ultrasound, and function in preterm infants receiving NIV-NAVA. Diaphragmatic ultrasound was performed to determine diaphragm inspiratory (DTI) and expiratory thickness (DTE) and diaphragmatic thickening fraction (DTF) during and after NIV-NAVA. Lung ultrasound score was assessed and Edi was recorded. Results 36 preterm infants were included, 20 had primary and 16 post-extubation NIV-NAVA. Mean gestational age at birth and birth weight were 27.4 weeks and 1004 grams. DTI and DTE remained stable during NIV-NAVA, but increased after stopping, whereas Edi remained stable. DTF was highly variable and did not change. DTF/Edi peak did not change over time on or after NIV-NAVA. LUS decreased gradually during the study period. No significant differences were found between infants on primary or post-extubation support except for DTF at inclusion. Conclusion In preterm infants supported with NIV-NAVA, DT and diaphragm function remained stable during the study period, after stopping DT increased. No differences between primary and post-extubation NIV-NAVA were found.