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

Abstract

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...

Neonatal and Adult ICU Ventilators to Provide Ventilation in Neonates, Infants, and Children: A Bench Model Study

“…Additionally, this knowledge could be of major interest when comparing improved patient-ventilator synchrony documented with neurally adjusted ventilatory assist. 8,9 The purpose of this study was to investigate, using a bench model, the hypothesis that neonatal and/or adult ventilators equipped with neonatal/pediatric modes currently do not reliably administer pressure support (PS) in the absence or presence of air leaks.…”

“…However, in our bench test, the trigger delays measured for the Servo-i were in line with the values reported in clinical settings. 8,9,24 Pressurization. In the pediatric literature, there are a striking lack of data on the possible clinical impact of pressurization capacities of mechanical ventilators.…”

Feasibility Study on Neurally Adjusted Ventilatory Assist in Noninvasive Ventilation After Cardiac Surgery in Infants

“…2 Adult and pediatric studies showed that NAVA increases breath-to-breath variability and improves patient-ventilator synchrony and patient comfort. [3][4][5][6][7][8][9] This last improvement is also effective in NIV in adult and pediatric subjects 10,11 and in very low birthweight infants, even in the presence of large leaks. 12 To our knowledge, no previous study was designed to evaluate this ventilation mode exclusively in the postoperative period after cardiac surgery in newborns.…”

Influence of Different Interfaces on Synchrony During Pressure Support Ventilation in a Pediatric Setting: A Bench Study

“…Compared with adults, children have a relatively higher breathing frequency, which can adversely affect patient-ventilator synchrony during PSV. 11,12 However, ventilator settings and interfaces used affect patient-ventilator synchrony in both cases. 13 Although neurally adjusted ventilatory assist (NAVA) has been proposed as a partial ventilatory support mode to improve patient-ventilator synchrony, 11,14,15 its use has been limited by the elevated cost of the catheter and need for specific equipment.…”

“…11,12 However, ventilator settings and interfaces used affect patient-ventilator synchrony in both cases. 13 Although neurally adjusted ventilatory assist (NAVA) has been proposed as a partial ventilatory support mode to improve patient-ventilator synchrony, 11,14,15 its use has been limited by the elevated cost of the catheter and need for specific equipment. Therefore, PSV still remains, in most adult and pediatric ICUs, the accepted standard for delivering partial ventilatory support during invasive and noninvasive ventilation.…”