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...

This is the first systematic description of EAdi evolution in children during their stay in the PICU. In our patient cohort, diaphragm activity was frequently low in conventional ventilation, suggesting that overassistance or oversedation is common in clinical practice. EAdi monitoring appears to be a helpful tool to detect such situations.

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