Neurally Adjusted Ventilatory Assist Increases Respiratory Variability and Complexity in Acute Respiratory Failure

Schmidt, Matthieu; Demoule, Alexandre; Cracco, Christophe; Gharbi, Alexandre; Fiamma, Marie-Noëlle; Straus, Christian; Duguet, Alexandre; Gottfried, S. B.; Similowski, Thomas

doi:10.1097/aln.0b013e3181cea375

Cited by 98 publications

(108 citation statements)

References 38 publications

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“…Numerous studies have shown that NAVA efficiently unloads the respiratory muscles (8,9) and delivers more synchronous ventilation than PSV (5,9-12). Furthermore, it was shown that ventilator pressures (during NAVA) follow the natural variability in breathing pattern (13)(14)(15).In smaller patients, NAVA improves patient-ventilator synchrony, as shown in a small physiological trial in seven premature infants (16). In the pediatric population, NAVA has been shown to be feasible (17,18) and to be more in phase with the patient's breathing (19).…”

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Neurally adjusted ventilatory assist improves patient–ventilator interaction in infants as compared with conventional ventilation

et al. 2012

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Background: Neurally adjusted ventilatory assist (NaVa) is a mode of ventilation controlled by the electrical activity of the diaphragm (edi). The aim was to evaluate patient-ventilator interaction in infants during NaVa as compared with conventional ventilation. Methods: Infants were successively ventilated with NaVa, pressure control ventilation (PcV), and pressure support ventilation (PsV). edi and ventilator pressure (Pvent) waveforms were compared and their variability was assessed by coefficients of variation. results: Ten patients (mean age 4.3 ± 2.4 mo and weight 5.9 ± 2.2 kg) were studied. In PcV and PsV, 4 ± 4.6% and 6.5 ± 7.7% of the neural efforts failed to trigger the ventilator. This did not occur during NaVa. Trigger delays were shorter with NaVa as compared with PcV and PsV (93 ± 20 ms vs. 193 ± 87 ms and 135 ± 29 ms). During PcV and PsV, the ventilator cycled off before the end of neural inspiration in 12 ± 13% and 21 ± 19% of the breaths (0 ± 0% during NaVa). During PcV and PsV, 24 ± 11% and 25 ± 9% of the neural breath cycle was asynchronous with the ventilator as compared with 11 ± 3% with NaVa. a large variability was observed for edi in all modes, which was transmitted into Pvent during NaVa (coefficient of variation: 24 ± 8%) and not in PcV (coefficient of variation 2 ± 1%) or PsV (2 ± 2%). conclusion: NaVa improves patient-ventilator interaction and delivers adequate ventilation with variable pressure in infants.c onventional modes of mechanical ventilation are clearly limited in their ability to provide synchrony between the patient and the assist delivered, as demonstrated repeatedly in adults (1,2) and more recently in children (3). Patientventilator asynchrony has been associated with poor clinical outcome (1,2,4). Despite the attempt to improve synchrony with "patient-triggered" modes such as pressure control ventilation (PCV) or pressure support ventilation (PSV), 25% of adult patients show more than 10% asynchrony with the ventilator (1,2,5). In pediatric patients, synchrony is particularly difficult to achieve because of the small tidal volumes, high respiratory rates, and weak airway flows and pressures. Ironically, during synchronized intermittent mandatory ventilation, more than half of the patient's breathing cycle is spent in asynchrony (3) with the ventilator.Besides the poor timing between the patient and the ventilator, patient-ventilator asynchrony also includes the inability of the ventilator to respond to patient demand and the natural breath-to-breath variability. Respiratory variability is a sign of a well functioning respiratory system (6). By definition, PCV and PSV deliver fixed levels of assist, thereby offering no possibility to respond to the patient's respiratory demand and variability.Neurally adjusted ventilatory assist (NAVA) is a mode of mechanical ventilation that delivers assist in time and in proportion to the electrical activity of the diaphragm (Edi) on a breath-by-breath basis (7). Numerous studies have shown that NAVA efficiently unloads the respirat...

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Neurally adjusted ventilatory assist improves patient–ventilator interaction in infants as compared with conventional ventilation

et al. 2012

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“…Eadi signal was integrated between the same two time points to obtain the corresponding integrated Eadi value (ʃEadi), to represent total inspiratory demand [9]. Peak Eadi value was captured and compared with ʃEadi to …”

Section: Discussionmentioning

confidence: 99%

“…Eadi value in this study as it is more physiologically relevant as total inspiratory demand and readily calculated [9].…”

Section: Discussionmentioning

confidence: 99%

“…Traditionally, the Coefficient of Variation (CV = standard deviation/mean) in Vt, ʃEadi and Ti over all breaths for each patient in each ventilator mode was calculated [4,9] for variation analysis. However, normality was assessed using a Kolmogorov-Smirnow test that showed that some parameters were not normally distributed.…”

Section: Variation Analysis -Robust Coefficient Of Variationmentioning

confidence: 99%

“…NAVA also increases respiratory variability in Vt and flow related variables compared to PS [6,9]. However, no studies make these comparisons relative to the inspiratory demand (Eadi), which may vary between modes and patients.…”

Section: Introductionmentioning

confidence: 99%

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Neurally Adjusted Ventilatory Assist Increases Respiratory Variability and Complexity in Acute Respiratory Failure

Abstract: Compared with PSV, NAVA increases the breathing pattern variability and complexity of flow, whereas the complexity of EAdi is unchanged. Whether this improves clinical outcomes remains to be determined.

Cited by 98 publications

References 38 publications

Neurally adjusted ventilatory assist improves patient–ventilator interaction in infants as compared with conventional ventilation

Neurally adjusted ventilatory assist improves patient–ventilator interaction in infants as compared with conventional ventilation

NAVA enhances tidal volume and diaphragmatic electro-myographic activity matching: a Range90 analysis of supply and demand

Automated versus non-automated weaning for reducing the duration of mechanical ventilation for critically ill adults and children

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