Neurally Adjusted Ventilatory Assist vs Pressure Support Ventilation for Noninvasive Ventilation During Acute Respiratory Failure A Crossover Physiologic Study
ABSTRACT ABSTRACT BACKGROUND:Patient-ventilator asynchrony is common during noninvasive ventilation (NIV) with pressure support ventilation (PSV). We examined the effect of neurally adjusted ventilator assist (NAVA) delivered through a facemask on synchronization in patients with acute respiratory failure (ARF). METHODS:This was a prospective physiological crossover study of 13 patients with ARF (median PaO(2)/FiO(2) 196 [IQR: 142-225]) given two 30-min trials of NIV with PSV and NAVA in random order. Diaphragm electrical activity (EAdi), neural inspiratory time (Tin), trigger delay, asynchrony index (AI), arterial blood gases (ABGs), and patient discomfort were recorded. RESULTS:There were significantly fewer asynchrony events during NAVA than PSV (10 [IQR: 5-14] events vs. 17 [IQR: 8-24] events, p = 0.017) and the occurrence of severe asynchrony (AI > 10%) was also less under NAVA (p = 0.027). Ineffective efforts and delayed cycling were significantly less with NAVA (p < 0.05 for both). NAVA was also associated with reduced trigger delay (0 [IQR: 0-30] ms vs. 90 [IQR: 30-130] ms, p < 0.001) and inspiratory time in excess (10 [IQR: 0-28] ms vs. 125 [IQR: 20-312] ms, p < 0.001), but Tin was similar under PSV and NAVA. EAdi max was higher during NAVA than PSV (p = 0.017). There were no significant differences in ABGs and patient discomfort under PSV and NAVA. CONCLUSION:In view of specific experimental conditions, our comparison of PSV and NAVA indicated that NAVA significantly reduced severe patient-ventilator asynchrony and resulted in similar improvements in gas exchange during NIV for ARF.Trial registry: ClinicalTrials.gov No. NCT01426178.
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ABSTRACT: Patient-ventilator interaction represents an important clinical challenge during non-invasive ventilation (NIV). Doorduin and colleagues' study shows that non-invasive neurally adjusted ventilatory assist (NAVA) improves patient-ventilator interaction compared with pressure support ventilation in patients with chronic obstructive pulmonary disease. There is no doubt nowadays that NAVA is the most effective mode of improving the synchrony between patient and machine, but the key question for the clinicians is whether or not this will make a difference to the patient's outcome. The results of the study still do not clarify this issue because of the very low clinically important dyssynchrony, like wasted efforts, in the population studied. Air leaks play an important role in determining patient-ventilator interaction and therefore NIV success or failure. Apart from the use of a dedicated NIV ventilator or specific modes of ventilation like NAVA, the clinicians should be aware that the choice of interface, the humidification system and the appropriate sedation are key factors in improving patient-ventilator synchrony.Critical care (London, England) 01/2014; 18(6):670. DOI:10.1186/s13054-014-0670-2 · 5.04 Impact Factor
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ABSTRACT: The need for intubation after a noninvasive ventilation (NIV) failure is frequent in the pediatric intensive care unit (PICU). One reason is patient-ventilator asynchrony during NIV. Neurally adjusted ventilatory assist (NAVA) is a mode of ventilation controlled by the patient's neural respiratory drive. The aim of this study was to assess the feasibility and tolerance of NIV-NAVA in children and to evaluate its impact on synchrony and respiratory effort. This prospective, physiologic, crossover study included 13 patients requiring NIV in the PICU of Sainte-Justine's Hospital from October 2011 to May 2013. Patients were successively ventilated in conventional NIV as prescribed by the physician in charge (30 minutes), in NIV-NAVA (60 minutes), and again in conventional NIV (30 minutes). Electrical activity of the diaphragm (EAdi) and airway pressure were simultaneously recorded to assess patient-ventilator synchrony. NIV-NAVA was feasible and well tolerated in all patients. One patient asked to stop the study because of anxiety related to the leak-free facial mask. Inspiratory trigger dys-synchrony and cycling-off dys-synchrony were significantly shorter in NIV-NAVA versus initial and final conventional NIV periods (both P <0.05). Wasted efforts were also decreased in NIV-NAVA (all values expressed as median and interquartile values) (0 (0 to 0) versus 12% (4 to 20) and 6% (2 to 22), respectively; P <0.01). As a whole, total time spent in asynchrony was reduced to 8% (6 to 10) in NIV-NAVA, versus 27% (19 to 56) and 32% (21 to 38) in conventional NIV before and after NIV-NAVA, respectively (P =0.05). NIV-NAVA is feasible and well tolerated in PICU patients and allows improved patient-ventilator synchronization. Larger controlled studies are warranted to evaluate the clinical impact of these findings. ClinicalTrials.gov NCT02163382 . Registered 9 June 2014.Critical Care 12/2015; 19(1). DOI:10.1186/s13054-015-0770-7 · 5.04 Impact Factor
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ABSTRACT: 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. 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. 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. Patient-ventilator inspiratory asynchronies and trigger delay were dramatically lower in NAVA mode than in PAC mode during NIV in infants with severe bronchiolitis. Pediatr Pulmonol. © 2014 Wiley Periodicals, Inc. © 2014 Wiley Periodicals, Inc.Pediatric Pulmonology 12/2014; DOI:10.1002/ppul.23139 · 2.38 Impact Factor