Neurally adjusted ventilator assist versus pressure support ventilation for noninvasive ventilation during acute respiratory failure: a cross-over physiological 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: After the institution of positive-pressure ventilation, the use of noninvasive ventilation (NIV) through an interface substantially increased. The first technique was continuous positive airway pressure; but, after the introduction of pressure support ventilation at the end of the 20th century, this became the main modality. Both techniques, and some others that have been recently introduced and which integrate some technological innovations, have extensively demonstrated a faster improvement of acute respiratory failure in different patient populations, avoiding endotracheal intubation and facilitating the release of conventional invasive mechanical ventilation. In acute settings, NIV is currently the first-line treatment for moderate-to-severe chronic obstructive pulmonary disease exacerbation as well as for acute cardiogenic pulmonary edema and should be considered in immunocompromised patients with acute respiratory insufficiency, in difficult weaning, and in the prevention of postextubation failure. Alternatively, it can also be used in the postoperative period and in cases of pneumonia and asthma or as a palliative treatment. NIV is currently used in a wide range of acute settings, such as critical care and emergency departments, hospital wards, palliative or pediatric units, and in pre-hospital care. It is also used as a home care therapy in patients with chronic pulmonary or sleep disorders. The appropriate selection of patients and the adaptation to the technique are the keys to success. This review essentially analyzes the evidence of benefits of NIV in different populations with acute respiratory failure and describes the main modalities, new devices, and some practical aspects of the use of this technique.International journal of chronic obstructive pulmonary disease. 01/2014; 9:837-852.
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ABSTRACT: IntroductionDelivering synchronous assist during non-invasive ventilation (NIV) is challenging with flow or pressure controlled ventilators, especially in patients with chronic obstructive pulmonary disease (COPD). Neurally adjusted ventilatory assist (NAVA) uses diaphragm electrical activity (EAdi) to control the ventilator. We evaluated patient-ventilator interaction in patients with COPD during NIV with pressure support ventilation (PSV) and NAVA using a recently introduced automated analysis.Methods Twelve COPD patients underwent three 30-minute trials: 1) PSV with dedicated NIV ventilator (NIV-PSVVision), 2) PSV with intensive care unit (ICU) ventilator (NIV-PSVServo-I), and 3) with NIV-NAVA. EAdi, flow, and airway pressure were recorded. Patient-ventilator interaction was evaluated by comparing airway pressure and EAdi waveforms with automated computer algorithms. The NeuroSync index was calculated as the percentage of timing errors between airway pressure and EAdi.ResultsThe NeuroSync index was higher (larger error) for NIV-PSVVision (24 [IQR 15-30] %) and NIV-PSVServo-I (21 [IQR 15-26] %) compared to NIV-NAVA (5 [IQR 4-7] %; P <0.001). Wasted efforts, trigger delays and cycling-off errors were less with NAVA (P <0.05 for all). The NeuroSync index and the number of wasted efforts were strongly correlated (r2¿=¿0.84), with a drastic increase in wasted efforts after timing errors reach 20%.Conclusions In COPD patients, non-invasive NAVA improves patient-ventilator interaction compared to PSV, delivered either by a dedicated or ICU ventilator. The automated analysis of patient-ventilator interaction allowed for an objective detection of patient-ventilator interaction during NIV. In addition, we found that progressive mismatch between neural effort and pneumatic timing is associated with wasted efforts.Critical care (London, England) 10/2014; 18(5):550. · 4.72 Impact Factor
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ABSTRACT: Los mayores avances en ventilación mecánica de los últimos años se han producido en el desarrollo de nuevos modos de ventilación asistida. En comparación con los modos tradicionales como la ventilación controlada-asistida o la presión de soporte, ofrecen una serie de ventajas fisiológicas así como un mayor control sobre el ventilador por parte del paciente. Basados en la utilización de algoritmos de control de asa cerrada que incorporan información de la mecánica, la actividad de la musculatura respiratoria y del estímulo respiratorio, estos modos están diseñados específicamente para mejorar la sincronía paciente-ventilador y reducir el trabajo respiratorio. Dependiendo de las características de funcionamiento específicas de cada modo, estos pueden ayudar en los esfuerzos respiratorios espontáneos del paciente de forma sincronizada en tiempo y magnitud, adaptarse a sus demandas, realizar protocolos automatizados de reducción del soporte y devolver al patrón respiratorio una variabilidad más fisiológica. El clínico tiene ahora a su disposición modos que permiten individualizar y optimizar la asistencia ventilatoria mecánica en la compleja transición de la ventilación controlada a la ventilación espontánea-asistida. La creciente evidencia de las ventajas fisiológicas y clínicas de estos nuevos modos así como las nuevas posibilidades de monitorización que ofrecen, están llevando a su paulatina introducción en la práctica diaria. Futuros estudios permitirán aumentar nuestro conocimiento acerca de estos modos y deberán determinar si sus beneficios se traducen en mejores resultados clínicos.Medicina Intensiva (English Edition). 05/2014;