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

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. 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 aeration score was assessed and Edi was recorded. Thirty-six 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 g. DTI remained stable during the study period, whereas DTE increased after stopping NIV-NAVA. Edi remained stable during and after NIV-NAVA. DTF was highly variable and did not change. Ultrasound-derived neuromechanical efficiency (= DTF/Edi

conclusionIn 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. WHAT IS KNOWN: • The diaphragm is the main respiratory muscle and can be assessed reliably through diaphragmatic ultrasound in preterm infants. • Non-invasive neurally adjusted ventilatory assist (NIV-NAVA) relies on the function of the diaphragm for delivering synchronized and proportional respiratory support. WHAT IS NEW: • Diaphragmatic thickness did not change during NIV-NAVA but increased after stopping. • Diaphragmatic function remained stable during and after NIV-NAVA.