Neurally adjusted ventilatory assist improves patient–ventilator interaction
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To determine if, compared with pressure support (PS), neurally adjusted ventilatory assist (NAVA) reduces trigger delay, inspiratory time in excess, and the number of patient–ventilator asynchronies in intubated patients.
Prospective interventional study in spontaneously breathing patients intubated for acute respiratory failure. Three consecutive periods of ventilation were applied: (1) PS1, (2) NAVA, (3) PS2. Airway pressure, flow, and transesophageal diaphragmatic electromyography were continuously recorded.
All results are reported as median (interquartile range, IQR). Twenty-two patients were included, 36.4% (8/22) having obstructive pulmonary disease. NAVA reduced trigger delay (ms): NAVA, 69 (57–85); PS1, 178 (139–245); PS2, 199 (135–256). NAVA improved expiratory synchrony: inspiratory time in excess (ms): NAVA, 126 (111–136); PS1, 204 (117–345); PS2, 220 (127–366). Total asynchrony events were reduced with NAVA (events/min): NAVA, 1.21 (0.54–3.36); PS1, 3.15 (1.18–6.40); PS2, 3.04 (1.22–5.31). The number of patients with asynchrony index (AI) >10% was reduced by 50% with NAVA. In contrast to PS, no ineffective effort or late cycling was observed with NAVA. There was less premature cycling with NAVA (events/min): NAVA, 0.00 (0.00–0.00); PS1, 0.14 (0.00–0.41); PS2, 0.00 (0.00–0.48). More double triggering was seen with NAVA, 0.78 (0.46–2.42); PS1, 0.00 (0.00–0.04); PS2, 0.00 (0.00–0.00).
Compared with standard PS, NAVA can improve patient–ventilator synchrony in intubated spontaneously breathing intensive care patients. Further studies should aim to determine the clinical impact of this improved synchrony.
KeywordsMechanical ventilation Patient–ventilator interaction Neurally adjusted ventilatory assist Pressure support Partial ventilatory assist
The authors wish to thank the Lancardis Foundation for its financial support, and Dr. Angèle Gayet-Ageron, Division of Clinical Epidemiology, University Hospital and Faculty of Medicine of Geneva, University of Geneva, Switzerland for her invaluable help with statistics.
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