Effects of Neurally Adjusted Ventilatory Assist on Lung Ultrasound Aeration and Diaphragmatic Function in Extremely Preterm Infants With Evolving or Established Bronchopulmonary Dysplasia.

BACKGROUND

Neurally adjusted ventilatory assist (NAVA) delivers ventilatory support proportional to diaphragmatic electrical activity, improving patient-ventilator synchrony. Its effects on lung aeration and diaphragmatic workload in extremely preterm infants have not been well characterized.

OBJECTIVES

We hypothesized that initiation of NAVA in preterm infants born at < 32 weeks' gestation would result in improved lung recruitment while allowing effective ventilation at lower airway pressures without increasing diaphragmatic workload.

METHODS

This prospective observational pilot study was conducted in a tertiary neonatal intensive care unit. Nineteen preterm infants (median gestational age 24 + 5 weeks; median birth weight 700 g, range 380-1352 g) were transitioned to NAVA at a median postnatal age of 30 + 5 days according to a pre-specified unit protocol. Lung ultrasound aeration scores (LUS), diaphragmatic excursion and thickness, peak electrical diaphragmatic activity (EAdi peak), mean airway pressure (MAP), and FiO2 were measured immediately before and 1 h after NAVA initiation. Paired statistical analyses were performed.

RESULTS

LUS decreased markedly following NAVA initiation (mean 15.21 ± 3.26 vs. 7.11 ± 2.47; p < 0.001; Cohen's d = 3.02), with the effect observed in both invasive and non-invasive NAVA groups. MAP decreased significantly (11.82 ± 1.63 vs. 9.56 ± 1.64 cmH2O; p < 0.001) and FiO2 showed a non-significant trend towards improvement (0.35 vs. 0.32; p = 0.020). Diaphragmatic excursion (7.05 ± 2.1 vs. 6.7 ± 2.2 mm; p = 0.650) and EAdi peak (8.4 vs. 8.3 mV; p = 0.839) were unchanged.

CONCLUSIONS

In this pilot cohort, initiation of NAVA in extremely preterm infants was associated with rapid improvement in lung ultrasound aeration scores and reduced ventilatory pressures, without evidence of increased diaphragmatic loading. These findings are hypothesis-generating and larger controlled studies are needed to confirm them.