Neurally Adjusted Ventilatory Assist (NAVA) is a specialized method of breathing support used for fragile newborns in the Neonatal Intensive Care Unit (NICU). Unlike traditional mechanical ventilation, which delivers a fixed amount of pressure or volume at a set time, NAVA is designed to be gentler and more synchronized with the infant’s own respiratory drive. This modern approach helps premature or critically ill newborns by providing assistance that closely matches their natural breathing patterns.
The Core Difference in NAVA
The fundamental distinction of NAVA lies in its use of the electrical activity of the diaphragm (Edi) to guide the ventilator’s actions. The Edi signal is the electrical impulse transmitted from the brain, down the phrenic nerve, that tells the diaphragm muscle to contract and initiate a breath. This signal represents the patient’s precise neural command, reflecting the desired timing, frequency, and intensity of the breath.
To capture this signal, a specialized catheter equipped with electrodes is positioned in the infant’s esophagus, near the diaphragm. The catheter, which often doubles as a feeding tube, measures the Edi more than 60 times per second, effectively reading the brain’s intent to inhale. Unlike conventional ventilation, which triggers after the diaphragm has already contracted, NAVA is triggered directly by the neural signal before the mechanical breath even begins.
The ventilator uses the measured Edi signal as a blueprint for the delivered breath. The assistance provided is directly proportional to the strength of the infant’s Edi signal. If the infant’s brain signals a stronger, larger breath, the ventilator delivers more pressure, and conversely, less pressure is given for a weaker effort. This real-time, proportional support ensures that the machine supports exactly what the infant’s body is trying to achieve, resulting in superior synchrony.
Why Traditional Ventilation Poses Challenges for Newborns
Conventional mechanical ventilation (CMV) modes rely on a set rhythm and fixed parameters. These systems are triggered by mechanical changes, such as a change in air flow or pressure, which occurs after the infant has already begun their inspiratory effort. A time delay exists between the infant’s neural command to breathe and the machine’s response, even with flow or pressure triggering.
This delay creates patient-ventilator asynchrony, where the infant’s breathing effort is mismatched with the machine’s breath delivery. Asynchrony is common in newborns due to their high respiratory rates and variable breathing patterns. Mismatched timing includes missed triggers, where the machine fails to recognize an attempt to breathe, or premature cycling, where the machine ends the breath before the infant is finished inhaling.
Asynchrony forces the neonatal lungs to endure cycles of over- or under-inflation, creating excessive pressure swings. This can lead to volutrauma (lung injury caused by excessive volume) or barotrauma (injury from high peak pressures). The mechanical stress contributes to the development or worsening of chronic lung disease, also known as bronchopulmonary dysplasia (BPD). Traditional ventilation also tends to suppress the infant’s respiratory drive, leading to disuse atrophy of the diaphragm muscle, which makes weaning from the ventilator more difficult.
Clinical Advantages of Using NAVA in Neonatal Care
The direct, proportional assistance offered by NAVA translates into several clinical benefits for neonates. Improved lung protection is achieved by reducing the damaging effects of high pressure and volume. Because breath delivery is synchronized with the infant’s neural drive, the peak inspiratory pressure (PIP) and mean airway pressure required are often significantly lower. This reduction in pressure minimizes both barotrauma and volutrauma, protecting the immature lungs.
NAVA enhances patient comfort and synchrony, allowing the infant to control their respiratory rate, inspiratory time, and tidal volume. This improved interaction results in fewer ineffective breathing efforts and a lower asynchrony index. Better synchronization means neonates require less sedation, as they are not fighting against arbitrary machine timing. A reduction in the need for sedating agents, such as opioids, supports better neurological development and sleep quality.
The technology also facilitates a faster weaning process, which is the transition off mechanical support. By allowing the infant’s respiratory muscles to remain active, NAVA prevents the disuse atrophy often seen with fully controlled conventional ventilation. The Edi signal provides clinicians with continuous, objective feedback on the infant’s respiratory effort and readiness to breathe independently. Early application of NAVA has been associated with weaning from invasive mechanical ventilation sooner than infants on conventional modes.