Noninvasive NAVA Versus NIPPV in Low Birthweight Premature Infants

Very low birthweight (VLBW) premature infants in the NICU (Neonatal Intensive Care Unit) frequently require respiratory support for prolonged periods of time. Invasive mechanical ventilation (which requires intubating the baby with a tube to provide breaths) can lead to ventilator induced lung injury. Because of this, noninvasive respiratory support has become increasingly popular, as this form of ventilation has been shown to reduce the incidence of permanent lung injury.

There are several methods to provide non-invasive support. The gentlest is continual flow of air and oxygen via nasal cannula. However, premature infants often develop apnea, either because the signals from their immature brain are not yet sufficient or because the muscles in the back of their throat do not get enough nerve signals to maintain sufficient opening. As a result, babies on nasal cannula often develop clinical apnea/bradycardia/desaturations. Before putting these babies back on invasive ventilation, clinicians often try to provide the baby with machine breaths while still on non-invasive ventilation.

This method is called nasal intermittent positive pressure ventilation and studies have demonstrated that this method reduces the need for re-intubation in VLBW infants (1) and reduces the rate of apneic events.

A newer method of non-invasive breathing support that has been FDA approved and used in VLBW infants, synchronizes the machine generated breath with the patient's own breath. Neurally adjusted ventilatory assist (NAVA) does this by replacing the standard nasogastric tube with a nasogastric tube that has sensors which detect the baby's natural diaphragm activity, which signal the ventilator to breath in synchronization with the baby. Studies have shown that the efficacy of nasal ventilation is significantly enhanced when the machine breath is synchronized with the patient breath (2). Synchronization also reduces diaphragmatic dysfunction (3). It can improve gas delivery, reduce work of breathing, and make patients demonstrably more comfortable (4).

Neurally Adjusted Ventilatory Assist (NAVA) is a mode of partial support. NAVA can be used both in intubated patients (invasive NAVA) as well as in extubated patients who require noninvasive positive pressure ventilation (noninvasive NAVA) (5). Invasive NAVA has been shown to deliver equivalent ventilation while requiring lower peak inspiratory pressure, as well as reduced respiratory muscle load, compared to conventional pressure support ventilation.