Changes in Respiratory Patterns From Pressure Control Ventilation to Neurally Adjusted Ventilatory Assist Assessed by Electrical Impedance Tomography

INTRODUCTION: Neurally Adjusted Ventilatory Assist (NAVA) is increasingly used as ventilatory support for preterm infants. Changes in ventilation distribution and respiratory patterns during the transition from patient-triggered time-cycled Pressure Controlled Ventilation (PCV) to NAVA have not yet been studied. This study aimed to evaluate the impact of ventilation mode (PCV and NAVA, respectively) on ventilation distribution and breathing patterns in preterm infants with Electrical Impedance Tomography. METHODS: This study included 16 premature infants at Oulu University Hospital who participated in the observational CRADL project and were on NAVA. EIT data was retrospectively assessed by choosing a 1-min stable recording before and after the change from one to the other mode. The primary endpoint was changes in global and regional ventilation parameters (ΔZ), and the secondary endpoints were Centers of Ventilation (CoVs), the amount of silent spaces, and the duration of inspiratory and respiratory cycle times. RESULTS: A larger variation in the global tidal impedance variation (p < 0.05) and the respiratory cycle time (p < 0.05) was observed on NAVA than on PCV. Sighs, which were determined as a breath impedance change twice the size of an average breath on PCV, were more frequent during NAVA than PCV (5.1% vs 0.8%, respectively). Mean global or regional impedance variations or silent spaces did not differ between PCV and NAVA. CONCLUSION: NAVA allowed more variable breathing patterns during invasive respiratory support than patient-triggered PCV. However, variability in the respiratory cycle did not lead to systematic changes in ventilation distribution or silent spaces.