Non-invasive ventilation with neurally adjusted ventilatory assist improves patient-ventilator interaction

Neurally adjusted ventilatory assist (NAVA) is a mode of partial ventilatory support in which neural inspiratory activity is monitored and cycled through the continuous esophageal recording of the diaphragmatic electromyogram (EAdi). In non invasive ventilation (NIV), leaks can lead to patient-ventilator asynchronies which are source of failure. Then, using NAVA in NIV could, like in invasive ventilation, improve patient-ventilator interaction. We analyzed whether, in comparison with pressure support (PS) with or without NIV algorithm (PS-NIV+ or PS-NIV0), NAVA with or without NIV algorithm (NAVA-NIV+ or NAVA-NIV0) could reduce inspiratory trigger delay, improve expiratory synchrony, and reduce the number of patient-ventilator asynchronies in NIV post-extubation patients. Randomly, the patients were ventilated during ten minutes in these four modes. Ventilatory breathing pattern and asynchronies (inspiratory and expiratory trigger delay, ineffective effort, autotriggering, double triggering, premature and late cycling) were compared between the four groups. Seventeen patients were observed. Switching from PS-NIV+ to NAVA-NIV+ and from PS-NIV0 to NAVA-NIV0 did not appear to significantly modify the pattern of breathing. Leaks were significantly higher between NIV+ and NIV0. Inspiratory trigger delay was significantly shorter in NAVA-NIV+ than in PS-NIV+ (20 vs. 980ms, p < 000.1) and in NAVA-NIV0 than PS-NIV0 (10 vs 590ms, p <0.001). The asynchrony index significantly decreased when PS was switched to NAVA in both conditions (21.7 vs 8.1% and 43.1 vs 6.2%; p <0.0001). Compared to PS, NIV with NAVA improves patient-ventilator interaction which did not depend of the leaks level.