Non-invasive neurally adjusted ventilatory assist in preterm infants with RDS: effect of changing NAVA levels.

Filip Cools,Michel Vervoort,Brenda Van Delft,Wilfried Cools,Julie Lefevere

doi:10.1007/s00431-021-04244-3

Abstract

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 cmH2O/µV and with increments of 0.5 cmH2O/µV every 3 min, up to a maximum level of 4.0 cmH2O/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) 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.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.Supplementary informationThe online version contains supplementary material available at 10.1007/s00431-021-04244-3.

Highlights

Adjusted ventilatory assist (NAVA) is a diaphragmtriggered ventilation that uses the electrical signal from the diaphragm (Edi) to proportionally assist the patient’s respiration
Preterm neonates with respiratory distress syndrome (RDS) supported with NIV-Neurally adjusted ventilatory assist (NAVA) display a biphasic response to changing NAVA levels with an identifiable breakpoint
Immature neural feedback mechanisms warrant careful monitoring of preterm infants when supported with NIV-NAVA

Summary

Introduction

Adjusted ventilatory assist (NAVA) is a diaphragmtriggered ventilation that uses the electrical signal from the diaphragm (Edi) to proportionally assist the patient’s respiration. As the NAVA level increases, the workload is shifted from the patient to the ventilator. This allows the work of breathing to be unloaded from the patient to the ventilator. The breakpoint is the point at which the NAVA support is at a level where the patient’s diaphragm is adequately unloaded. With a given Edi, increasing NAVA levels will result in increasing Peak inspiratory pressures (PIP). Once the breakpoint is reached, the respiratory muscle unloading is sufficient and further increase in NAVA level will not result in a higher PIP, because there will be a suppression of the patient’s inspiratory drive and the Edi will decrease [7]

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