We aimed to examine the effect of changing levels of support (NAVA level) during non-invasive neurally adjusted ventilatory assist (NIV-NAVA) in preterm infants with respiratory distress syndrome (RDS) on electrical diaphragm activity. This is a prospective, single-centre, interventional, exploratory study in a convenience sample. Clinically stable preterm infants supported with NIV-NAVA for RDS were eligible. Patients were recruited in the first 24 h after the start of NIV-NAVA. Following a predefined titration protocol, NAVA levels were progressively increased starting from a level of 0.5 cmH 2 O/µV and with increments of 0.5 cmH 2 O/µV every 3 min, up to a maximum level of 4.0 cmH 2 O/µV. We measured the evolution of peak inspiratory pressure and the electrical signal of the diaphragm (Edi) during NAVA level titration. Twelve infants with a mean (SD) gestational age at birth of 30.6 (3.5) weeks and birth weight of 1454 (667) g were enrolled. For all patients a breakpoint could be identified during the titration study. The breakpoint was on average (SD) at a level of 2.33 (0.58) cmH 2 O/µV. With increasing NAVA levels, the respiratory rate decreased significantly. No severe complications occurred.Conclusions: Preterm neonates with RDS supported with NIV-NAVA display a biphasic response to changing NAVA levels with an identifiable breakpoint. This breakpoint was at a higher NAVA level than commonly used in this clinical situation. Immature neural feedback mechanisms warrant careful monitoring of preterm infants when supported with NIV-NAVA.Trial registration: clinicaltrials.gov NCT03780842. Date of registration December 12, 2018. What is Known:• Non-invasive neurally adjusted ventilatory assist (NIV-NAVA) is a safe, feasible and effective way to support respiration in preterm infants.• Intact neural feedback mechanisms are needed to protect the lung from overdistension in neurally adjusted ventilatory assist. What is New:• Preterm infants with acute RDS have a similar pattern of respiratory unloading as previously described.• Neural feedback mechanisms seem to be immature with the risk of insufficient support and lung injury due to overdistension of the lung.

Objective: to examine the effect of changing levels of support (NAVA-level) during neurally adjusted ventilatory assist (NAVA) in preterm infant with respiratory distress syndrome (RDS) on electrical diaphragm activity. Methods: we included preterm infants admitted to the NICU, who were clinically stable and supported with NAVA, either via an endotracheal tube or via a nasal interface. Patients were recruited in the first 24 hours after the start of NAVA. Following a predefined titration protocol, NAVA levels were progressively increased starting from a level of 0,5 cmH2O/µV and with increments of 0,5 cmH2O/µV every 3 minutes, up to a maximum level of 4,0 cmH2O/µV. Respiratory and ventilation parameters were continuously recorded. Results: Ten patients were studied on NIV-NAVA and three on invasive NAVA. The NIV-NAVA patients had an average gestational age at birth of 31,4 + 3,2 weeks and an average birth weight of 1615 + 609 g. For all patients a breakpoint could be identified during the titration study. The breakpoint was on average at a level of 2,35 + 0,63 cmH2O/µV in the NIV-NAVA group. With increasing NAVA levels, the respiratory rate decreased significantly. For the other parameters no clear trend was observed. No severe complications occurred. Conclusion: Preterm neonates with RDS supported with NAVA display a typical biphasic response to changing NAVA-levels with an identifiable breakpoint. This breakpoint was at a higher NAVA-level than commonly used in this clinical situation, suggesting that higher levels might be needed to optimally support preterm neonates with RDS.

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We aimed to examine the effect of changing levels of support (NAVA level) during non-invasive neurally adjusted ventilatory assist (NIV-NAVA) in preterm infants with respiratory distress syndrome (RDS) on electrical diaphragm activity. This is a prospective, single-centre, interventional, exploratory study in a convenience sample. Clinically stable preterm infants supported with NIV-NAVA for RDS were eligible. Patients were recruited in the first 24 hours after the start of NIV-NAVA. Following a predefined titration protocol, NAVA levels were progressively increased starting from a level of 0,5 cmH2O/µV and with increments of 0,5 cmH2O/µV every 3 minutes, up to a maximum level of 4,0 cmH2O/µV. We measured the evolution of peak inspiratory pressure (PIP) and the electrical signal of the diaphragm (Edi) during NAVA level titration. Twelve infants with a mean (SD) gestational age at birth of 30,6 (3,5) weeks and birth weight of 1454 (667) g were enrolled. For all patients a breakpoint could be identified during the titration study. The breakpoint was on average (SD) at a level of 2,33 (0,58) cmH2O/µV. With increasing NAVA levels, the respiratory rate decreased significantly. No severe complications occurred.Conclusions: Preterm neonates with RDS supported with NIV-NAVA display a biphasic response to changing NAVA levels with an identifiable breakpoint. This breakpoint was at a higher NAVA level than commonly used in this clinical situation. Immature neural feedback mechanisms warrant careful monitoring of preterm infants when supported with NIV-NAVA.Clinical trial registration: clinicaltrials.gov NCT03780842. Date of registration December 12, 2018.