Neurally Adjusted Ventilator Assist (NAVA) Reduces Asynchrony During Non-Invasive Ventilation for Severe Bronchiolitis

Background: To determine the prevalence of main inspiratory asynchrony events during non-invasive intermittent positive-pressure ventilation (NIV) for severe bronchiolitis. Ventilator response time and asynchrony were compared in neurally adjusted ventilator assist (NAVA) and in pressure assist/control (PAC) modes. Methods: This prospective physiological study was performed in a university hospital's paediatric intensive care unit and included 11 children (aged 35.2 +/- 23 days) with respiratory syncytial virus bronchiolitis with failure of nCPAP. Patients received NIV for 2 hr in PAC mode followed by 2 hr in NAVA mode. Electrical activity of the diaphragm and pressure curves were recorded for 10 min. Trigger delay, main asynchronies (auto-triggering, double triggering, or non-triggered breaths) were analyzed, and the asynchrony index was calculated for each period. Results: The asynchrony index was lower during NAVA than during PAC (3 + 3% vs. 38 + 21%, P < 0.0001), and the trigger delay was shorter (43.9 + 7.2 vs. 116.0 +/- 38.9 ms, P < 0.0001). Ineffective efforts were significantly less frequent in NAVA mode (0.54 +/- 1.5 vs. 21.8 +/- 16.5 events/min, P = 0.01). Patient respiratory rates were similar, but the ventilator rate was higher in NAVA than in PAC mode (59.5 +/- 17.9 vs. 49.8 +/- 8.5/min, P = 0.03). The TcPCO2 baselines values (64 +/- 12 mmHg vs. 62 +/- 9 mmHg during NAVA, P = 0.30) were the same and their evolution over the 2 hr study period (-6 + 10 mmHg vs. -12 + 17 mmHg during NAVA, P = 0.36) did not differ. Conclusion: Patient-ventilator inspiratory asynchronies and trigger delay were dramatically lower in NAVA mode than in PAC mode during NIV in infants with severe bronchiolitis. (C) 2014 Wiley Periodicals, Inc.