Neurally adjusted ventilatory assist

Paolo Navalesi, Federico Longhini, Paolo Navalesi, Federico Longhini

Abstract

Purpose of review: Compared with the conventional forms of partial support, neurally adjusted ventilatory assist was repeatedly shown to improve patient-ventilator synchrony and reduce the risk of overassistance, while guaranteeing adequate inspiratory effort and gas exchange. A few animal studies also suggested the potential of neurally adjusted ventilatory assist in averting the risk of ventilator-induced lung injury. Recent work adds new information on the physiological effects of neurally adjusted ventilatory assist.

Recent findings: Compared with pressure support, neurally adjusted ventilatory assist has been shown to improve patient-ventilator interaction and synchrony in patients with the most challenging respiratory system mechanics, such as very low compliance consequent to severe acute respiratory distress syndrome and high resistance and air trapping due to chronic airflow obstruction; enhance redistribution of the ventilation in the dependent lung regions; avert the risk of patient-ventilator asynchrony due to sedation; avoid central apneas; limit the risk of high (injurious) tidal volumes in patients with acute respiratory distress syndrome of varied severity; and improve patient-ventilator interaction and synchrony during noninvasive ventilation, irrespective of the interface utilized.

Summary: Several studies nowadays prove the physiological benefits of neurally adjusted ventilatory assist, as opposed to the conventional modes of partial support. Whether these advantages translate into improvement of clinical outcomes remains to be determined.

Figures

FIGURE 1
FIGURE 1
Publications on neurally adjusted ventilatory assist (NAVA) from 1999 to 2013. The studies related to NAVA yearly published from 1999 (first description of the technique) to 2013 are shown as a whole and divided according to the type of study: animal (black), adult (light gray) and pediatric patients (dark gray), and others (white), including reviews, editorials, and investigations on healthy individuals. After the introduction of NAVA in clinical use in 2008, the studies related to this mode progressively increased every year, either overall or considering the studies performed on adult and pediatric patients.
Box 1
Box 1
no caption available
FIGURE 2
FIGURE 2
Relation between patient's demand and ventilator support with different modes of partial assistance. The figure depicts the composite interplay among respiratory drive, pressure generated by the respiratory muscles (Pmus), and ventilatory output (i.e., volume and flow) during partial ventilator assist with different modes of ventilation. The output of the respiratory centers is modulated by stimuli from mechanoreceptors and chemoreceptors, and the cortical or limbic system. Sedatives also affect, directly or indirectly, the output of the respiratory centers. The amount of assistance delivered by the ventilator with the conventional modes (single dotted line), such as pressure support (PSV), assist control (A/C), and synchronized intermittent mandatory ventilation (SIMV), is not influenced by either drive or effort or ventilator output, which exposes this mode to the risk of overassistance. In contrast, with the proportional modes, the delivered support is affected by patient's demand indirectly, by the ventilatory output in proportional assist ventilation (PAV) (dashed-dotted line), or directly, by the neural output of the respiratory centers, as obtained by the electrical activity of the diaphragm (EAdi), in neurally adjusted ventilatory assist (NAVA) (dashed line). With NAVA, moreover, a changed neuromechanical coupling, changes in respiratory mechanics, or air leaks may not disturb the relation between neural output and mechanical support. See text for further explanations. Modified with permission from [2].

References

    1. Sinderby C, Navalesi P, Beck J, et al. Neural control of mechanical ventilation in respiratory failure. Nat Med 1999; 5:1433–1436.
    1. Navalesi P, Costa R. New modes of mechanical ventilation: proportional assist ventilation, neurally adjusted ventilatory assist, and fractal ventilation. Curr Opin Crit Care 2003; 9:51–58.
    1. Bellani G, Mauri T, Coppadoro A, et al. Estimation of patient's inspiratory effort from the electrical activity of the diaphragm. Crit Care Med 2013; 41:1483–1491.
    1. Colombo D, Cammarota G, Bergamaschi V, et al. Physiologic response to varying levels of pressure support and neurally adjusted ventilatory assist in patients with acute respiratory failure. Intensive Care Med 2008; 34:2010–2018.
    1. Vaschetto R, Cammarota G, Colombo D, et al. Effects of propofol on patient–ventilator synchrony and interaction during pressure support ventilation and neurally adjusted ventilatory assist. Crit Care Med 2014; 42:74–82.

    2. In patients receiving partial ventilatory assistance for ARF of varied causes, propofol affects gas exchange and breathing pattern to an extent that varies with the depth of sedation and the mode of ventilation. EAdi is decreased at increasing levels of sedation with both pressure support and NAVA, although to varying extent. Deep propofol sedation deteriorates patient–ventilator interaction and may cause asynchrony during pressure support, but not in NAVA.

    1. Berger KI, Sorkin IB, Norman RG, et al. Mechanism of relief of tachypnea during pressure support ventilation. Chest 1996; 109:1320–1327.
    1. Colombo D, Cammarota G, Alemani M, et al. Efficacy of ventilator waveforms observation in detecting patient–ventilator asynchrony. Crit Care Med 2011; 39:2452–2457.
    1. Terzi N, Pelieu I, Guittet L, et al. Neurally adjusted ventilatory assist in patients recovering spontaneous breathing after acute respiratory distress syndrome: physiological evaluation. Crit Care Med 2010; 38:1830–1837.
    1. Schmidt M, Demoule A, Cracco C, et al. Neurally adjusted ventilatory assist increases respiratory variability and complexity in acute respiratory failure. Anesthesiology 2010; 112:670–681.
    1. Patroniti N, Bellani G, Saccavino E, et al. Respiratory pattern during neurally adjusted ventilatory assist in acute respiratory failure patients. Intensive Care Med 2012; 38:230–239.

    2. In patients with ARF, increasing NAVA levels were associated with decreased EAdi, and, differently from pressure support, with small changes in tidal volume, but higher tidal volume variability. At the highest NAVA levels, the elevated tidal volume variability was associated with increased incidence of tidal volumes exceeding 8 and 10 ml/kg.

    1. Spahija J, de Marchie M, Albert M, et al. Patient–ventilator interaction during pressure support ventilation and neurally adjusted ventilatory assist. Crit Care Med 2010; 38:518–526.
    1. Brander L, Leong-Poi H, Beck J, et al. Titration and implementation of neurally adjusted ventilatory assist in critically ill patients. Chest 2009; 135:695–703.
    1. Gama de Abreu M, Belda FJ. Neurally adjusted ventilatory assist: letting the respiratory center take over control of ventilation. Intensive Care Med 2013; 39:1481–1483.
    1. Allo JC, Beck JC, Brander L, et al. Influence of neurally adjusted ventilatory assist and positive end-expiratory pressure on breathing pattern in rabbits with acute lung injury. Crit Care Med 2006; 34:2997–3004.
    1. Beck J, Campoccia F, Allo JC, et al. Improved synchrony and respiratory unloading by neurally adjusted ventilatory assist (NAVA) in lung-injured rabbits. Pediatr Res 2007; 61:289–294.
    1. Brander L, Sinderby C, Lecomte F, et al. Neurally adjusted ventilatory assist decreases ventilator-induced lung injury and nonpulmonary organ dysfunction in rabbits with acute lung injury. Intensive Care Med 2009; 35:1979–1989.
    1. Mauri T, Bellani G, Grasselli G, et al. Patient–ventilator interaction in ARDS patients with extremely low compliance undergoing ECMO: a novel approach based on diaphragm electrical activity. Intensive Care Med 2013; 39:282–291.

    2. In patients with severe ARDS breathing in pressure support while undergoing extracorporeal membrane oxygenation, the authors found a high incidence of premature cycling, irrespective of the cycling-off settings; in the same patients, NAVA was able to improve patient–ventilator synchrony to suboptimal level.

    1. Piquilloud L, Vignaux L, Bialais E, et al. Neurally adjusted ventilatory assist improves patient–ventilator interaction. Intensive Care Med 2011; 37:263–271.
    1. Bellani G, Coppadoro A, Patroniti N, et al. Clinical assessment of auto-positive end-expiratory pressure by diaphragmatic electrical activity during pressure support and neurally adjusted ventilatory assist. Anesthesiology 2014; 121:563–571.

    2. In intubated patients with auto-PEEP, the neural control of ventilation decreased the required pressure to overcome the auto-PEEP, in comparison with pressure support.

    1. Coisel Y, Chanques G, Jung B, et al. Neurally adjusted ventilatory assist in critically ill postoperative patients: a crossover randomized study. Anesthesiology 2010; 113:925–935.
    1. Wu XY, Huang YZ, Yang Y, et al. Effects of neurally adjusted ventilatory assist on patient–ventilator synchrony in patients with acute respiratory distress syndrome. Zhonghua Jie He He Hu Xi Za Zhi 2009; 32:508–512.
    1. Blankman P, Hasan D, van Mourik MS, Gommers D. Ventilation distribution measured with EIT at varying levels of pressure support and neurally adjusted ventilatory assist in patients with ALI. Intensive Care Med 2013; 39:1057–1062.

    2. In patients with ARDS of varied severity, NAVA was characterized by enhanced distribution of ventilation in the dependent lung regions, as opposed to pressure support. Also, NAVA resulted in a reduced risk of overassistance.

    1. Karagiannidis C, Lubnow M, Philipp A, et al. Autoregulation of ventilation with neurally adjusted ventilatory assist on extracorporeal lung support. Intensive Care Med 2010; 36:2038–2044.
    1. Tobin MJ, Mador MJ, Guenther SM, et al. Variability of resting respiratory drive and timing in healthy subjects. J Appl Physiol (1985) 1988; 65:309–317.
    1. Spieth PM, Carvalho AR, Pelosi P, et al. Variable tidal volumes improve lung protective ventilation strategies in experimental lung injury. Am J Respir Crit Care Med 2009; 179:684–693.
    1. Delisle S, Terzi N, Ouellet P, et al. Effect of ventilatory variability on occurrence of central apneas. Respir Care 2013; 58:745–753.

    2. In critically ill patients during the weaning process, compared with pressure support, NAVA avoided the episodes of overassistance during sleep, which corresponded to eliminating central apneas.

    1. Barwing J, Linden N, Ambold M, et al. Neurally adjusted ventilatory assist vs. pressure support ventilation in critically ill patients: an observational study. Acta Anaesthesiol Scand 2011; 55:1261–1271.
    1. Vagheggini G, Mazzoleni S, Vlad Panait E, et al. Physiologic response to various levels of pressure support and NAVA in prolonged weaning. Respir Med 2013; 107:1748–1754.
    1. Chao DC, Scheinhorn DJ, Stearn-Hassenpflug M. Patient–ventilator trigger asynchrony in prolonged mechanical ventilation. Chest 1997; 112:1592–1599.
    1. Thille AW, Rodriguez P, Cabello B, et al. Patient–ventilator asynchrony during assisted mechanical ventilation. Intensive Care Med 2006; 32:1515–1522.
    1. de Wit M, Miller KB, Green DA, et al. Ineffective triggering predicts increased duration of mechanical ventilation. Crit Care Med 2009; 37:2740–2745.
    1. Navalesi P. On the imperfect synchrony between patient and ventilator. Crit Care 2011; 15:181.
    1. Cereda M, Foti G, Marcora B, et al. Pressure support ventilation in patients with acute lung injury. Crit Care Med 2000; 28:1269–1275.
    1. Nava S, Bruschi C, Rubini F, et al. Respiratory response and inspiratory effort during pressure support ventilation in COPD patients. Intensive Care Med 1995; 21:871–879.
    1. Esteban A, Frutos-Vivar F, Muriel A, et al. Evolution of mortality over time in patients receiving mechanical ventilation. Am J Respir Crit Care Med 2013; 188:220–230.
    1. Demoule A, Girou E, Richard JC, et al. Increased use of noninvasive ventilation in French intensive care units. Intensive Care Med 2006; 32:1747–1755.
    1. Vignaux L, Vargas F, Roeseler J, et al. Patient–ventilator asynchrony during noninvasive ventilation for acute respiratory failure: a multicenter study. Intensive Care Med 2009; 35:840–846.
    1. Beck J, Brander L, Slutsky AS, et al. Noninvasive neurally adjusted ventilatory assist in rabbits with acute lung injury. Intensive Care Med 2008; 34:316–323.
    1. Hadj-Ahmed MA, Samson N, Bussieres M, et al. Absence of inspiratory laryngeal constrictor muscle activity during nasal neurally adjusted ventilatory assist in newborn lambs. J Appl Physiol (1985) 2012; 113:63–70.
    1. Cammarota G, Olivieri C, Costa R, et al. Noninvasive ventilation through a helmet in postextubation hypoxemic patients: physiologic comparison between neurally adjusted ventilatory assist and pressure support ventilation. Intensive Care Med 2011; 37:1943–1950.

    2. Compared with pressure support, NAVA dramatically improves patient–ventilator interaction and synchrony during NIV delivered by helmet, with no differences in gas exchange and neural drive.

    1. Navalesi P, Costa R, Ceriana P, et al. Noninvasive ventilation in chronic obstructive pulmonary disease patients: helmet versus facial mask. Intensive Care Med 2007; 33:74–81.
    1. Piquilloud L, Tassaux D, Bialais E, et al. Neurally adjusted ventilatory assist (NAVA) improves patient–ventilator interaction during noninvasive ventilation delivered by face mask. Intensive Care Med 2012; 38:1624–1631.

    2. Compared with pressure support, NAVA improved patient–ventilator interaction and reduced the asynchronous events in patients undergoing NIV through a facial mask. Gas exchange and neural drive were no different with the two modes.

    1. Schmidt M, Dres M, Raux M, et al. Neurally adjusted ventilatory assist improves patient–ventilator interaction during postextubation prophylactic noninvasive ventilation. Crit Care Med 2012; 40:1738–1744.

    2. During NIV, the application of a leak-compensating software significantly improved patient ventilator synchrony during pressure support, but produced little or no benefit in NAVA. With NAVA, the asynchronies caused by air leaks were irrelevant and significantly lower than in pressure support. There were more episodes of double triggering with NAVA than with pressure support.

    1. Bertrand PM, Futier E, Coisel Y, et al. Neurally adjusted ventilatory assist vs pressure support ventilation for noninvasive ventilation during acute respiratory failure: a crossover physiologic study. Chest 2013; 143:30–36.

    2. This study confirms in patients receiving NIV through a facial mask that NAVA improves the patient–ventilator interaction and synchrony and results in similar values of arterial blood gases and diaphragm electrical activity, as compared with pressure support.

Source: PubMed

Sponsorer og samarbeidspartnere

Medisinsk tilstand

Legemiddelintervensjoner

3
Abonnere