Neurally Adjusted Ventilatory Assist, or NAVA, is a mode of breathing support that uses the body’s own electrical signals to guide the ventilator’s action. This technology aims to align the machine’s function with the patient’s natural respiratory demands, providing assistance tailored to their breathing effort. It can be applied both invasively and non-invasively by detecting electrical activity in the diaphragm, the primary muscle used for breathing.
The Neural Signal and Ventilator Response
The process of breathing begins with a signal from the brain that travels down the phrenic nerve to the diaphragm. This signal causes the muscle to contract and flatten, drawing air into the lungs. Just before this muscular contraction, an electrical spike occurs. NAVA technology is designed to capture this specific electrical activity of the diaphragm, known as the Edi signal, using a specialized catheter that also serves a dual purpose for feeding and monitoring.
This catheter is fitted with a series of small electrodes that are positioned in the esophagus, adjacent to the diaphragm. The electrodes detect the Edi signal, which reflects the neural command for inspiration from the respiratory center of the brain. The ventilator continuously monitors this signal, allowing the machine to anticipate the patient’s inspiratory effort fractions of a second before it physically begins.
Once the Edi signal is detected, the ventilator processes this information in real-time. The strength of the electrical signal is proportional to the amount of effort the patient is exerting to breathe. The ventilator then delivers a corresponding level of pressurized air, meaning a stronger patient effort results in more support from the machine, and a weaker effort receives less. This proportional assistance ensures the ventilator’s response is matched to the patient’s neural respiratory drive.
Achieving Patient-Ventilator Synchrony
A significant challenge in conventional mechanical ventilation is patient-ventilator asynchrony. This occurs when the timing and volume of air delivered by the machine do not match the patient’s own breathing rhythm. The ventilator might force air in when the patient is trying to exhale, or fail to provide a breath when the patient initiates one. This conflict can lead to patient distress, an increased work of breathing, and potential lung injury.
NAVA addresses this issue by directly linking the ventilator’s function to the patient’s neural respiratory output. Because the ventilator is triggered by the Edi signal—the body’s own command to breathe—the timing of the delivered breath is synchronized with the patient’s intended inspiration. This creates a harmonious interaction where the machine assists the patient’s natural breathing pattern instead of fighting against it.
The near-elimination of asynchrony results in several benefits. Patients often experience greater comfort and may require less sedation. The work of breathing is reduced, preventing both under-assistance and over-assistance. By ensuring the support is appropriately scaled and timed, NAVA helps protect the lungs from the stresses associated with dyssynchronous breathing.
The Non-Invasive Application
The “non-invasive” aspect of Non-Invasive NAVA (NIV-NAVA) refers to the method of delivering air to the patient. Instead of requiring an endotracheal tube inserted into the windpipe (intubation), NIV-NAVA uses an external interface. These interfaces can include soft nasal prongs, a nasal mask, or a full-face mask that covers both the nose and mouth. The choice of interface depends on the patient’s size, condition, and comfort.
This approach stands in stark contrast to invasive ventilation. Intubation, while often necessary, carries inherent risks. It bypasses the natural defenses of the upper airway, increasing the risk of ventilator-associated pneumonia. Intubated patients require higher levels of sedation and are unable to speak, eat, or drink.
Avoiding intubation through the use of NIV-NAVA offers significant advantages. It lowers the risk of infections and complications associated with an artificial airway. Because patients can remain more awake and alert with less sedation, they may be able to communicate and interact more. This preservation of natural airway function and patient comfort is a benefit of this non-invasive application.
Patient Populations and Use Cases
Non-Invasive NAVA is particularly beneficial for specific patient populations, most notably premature infants. The respiratory systems of neonates are underdeveloped, and their control of breathing can be irregular. NIV-NAVA’s gentle and responsive support is well-suited to their delicate lungs and variable breathing patterns. Studies show that for extremely low-birth-weight infants, using NIV-NAVA can lead to shorter durations of oxygen therapy and reduced rates of bronchopulmonary dysplasia.
The technology’s ability to synchronize with the infant’s own respiratory drive helps avoid the potential harm of conventional ventilation, supporting lung development more naturally. This makes it an efficient and practical option in the neonatal intensive care unit (NICU).
While its use is prominent in neonatology, NIV-NAVA is also applied to other patient groups. Adults with Chronic Obstructive Pulmonary Disease (COPD) experiencing respiratory distress can benefit from the synchronized support, which may help them avoid intubation. It is also used for patients of all ages who are being weaned from long-term invasive ventilation, providing a transitional step that supports their own breathing effort as they regain strength.