Effect of Changing NAVA Levels on Tidal Ventilation in Extremely Preterm Infants Supported with NIV-NAVA

Introduction: Noninvasive neurally adjusted ventilatory assist (NIV-NAVA) is used in preterm infants as a synchronized and proportional mode of noninvasive ventilation. Finding the ideal NAVA level to support preterm infants remains challenging. Methods: A single-center prospective interventional study was conducted to study the effect of increasing NAVA levels on tidal ventilation measured with electrical impedance tomography (EIT). Preterm infants supported with NIV-NAVA were included. After a baseline registration and following a predefined titration protocol, NAVA levels were progressively increased by 0.5 cmH₂O/µV up to a NAVA level of 3 cmH₂O/µV. Before and during the titration procedure, the evolution of EIT parameters (end-expiratory lung impedance, end-inspiratory lung impedance, silent spaces, and center of ventilation) and respiratory parameters (electrical diaphragm activity [Edi] peak and minimum [Edi min] and peak inspiratory pressure [PIP]) were measured. Results: Sixteen patients with a mean (standard deviation) gestational age (GA) at birth of 26.7 (1.2) weeks and birth weight of 838 (205) g were included for analysis. EIT parameters did not change significantly with titration of NAVA levels. PIP increased significantly with each increase in NAVA level and Edi peak decreased significantly from NAVA level 1 tot 1.5 cmH₂O/µV. Edi min and transcutaneous CO₂ (TcCO₂) remained constant during the titration procedure. Conclusion: There was no effect of increasing NAVA levels on regional ventilation parameters. PIP increased with each increase in NAVA level, whereas Edi peak largely remained stable.