Non-invasive Neurally Adjusted Ventilatory Assist (NIV-NAVA)

Introduction And Core Concept

Represents a significant recent pediatric advance in neonatal respiratory support.
Functions as an advanced, neurally triggered, and neurally cycled mode of non-invasive respiratory support.
Delivers airway pressure proportionally to the electrical activity of the diaphragm (Edi).
Decouples the triggering mechanism from upper airway leaks or mechanical delays by utilizing the patient’s own central respiratory drive rather than pneumatic signals.

Requires an Edi catheter, which is a specialized, biocompatible nasogastric or orogastric tube embedded with an array of distal micro-electrodes.
Electrodes capture the crural diaphragmatic electromyogram signal representing direct output from the brainstem's respiratory center.
Ventilator software filters the raw signal to eliminate cardiac electrocardiogram artifacts and esophageal peristalsis noise to yield the processed Edi waveform.
Edi peak represents the maximum diaphragmatic contraction at end-inspiration, reflecting total neural inspiratory effort.
Edi min represents tonic diaphragmatic activity at end-expiration, which preserves functional residual capacity.

The ventilator delivers pressure continuously throughout the respiratory cycle based on the instantaneous Edi signal.
Delivered pressure equals NAVA level multiplied by the difference between Edi and Edi min, plus positive end-expiratory pressure.
The NAVA level is a clinician-set gain factor that scales the amount of pressure assistance provided for every microvolt of diaphragmatic effort.
Initial NAVA level settings typically start at 1 to 2 cmH2O/µV, with titration based on target Edi peaks of 5 to 20 µV.
Inspiration commences immediately when Edi rises above a minimal threshold, while expiratory cycling occurs when Edi drops to a set percentage of its peak value, ensuring precise neural synchrony.

Parameter	Conventional Non-Invasive Ventilation	Non-Invasive Neurally Adjusted Ventilatory Assist
Trigger Mechanism	Relies on pneumatic signals like flow or pressure deflections.	Relies on the electrical activity of the diaphragm.
Leak Independence	Highly susceptible to trigger failure and autotriggering from air leaks.	Synchrony remains entirely unaffected by air leaks around interfaces.
Patient-Ventilator Synchrony	Prone to mechanical delays, missed triggers, and double triggering.	Perfect synchrony by eliminating mechanical delays.
Diaphragmatic Protection	Risk of diaphragmatic atrophy or fatigue.	Prevents atrophy by requiring baseline effort and prevents fatigue via proportional assistance.
Airway Pressure Regulation	Delivers fixed pressure irrespective of effort.	Autoregulates pressure via a negative feedback loop to protect against volutrauma and barotrauma.

Prevention of extubation failure as a bridge for extremely low birth weight infants demonstrating borderline respiratory drive.
Primary support in respiratory distress syndrome as an alternative to nasal continuous positive airway pressure.
Management of evolving bronchopulmonary dysplasia by facilitating longer periods of non-invasive support and stabilizing fluctuating oxygen saturations.

Impaired central respiratory drive due to central apnea, severe hypoxic-ischemic encephalopathy, or heavy respiratory depressants.
Anatomical upper gastrointestinal anomalies preventing safe catheter passage, such as choanal atresia or tracheoesophageal fistula.
Congenital diaphragmatic hernia, where structural distortion prevents reliable electrode alignment.
Frequent dropouts to safety backup pneumatic ventilation modes indicate unsuitability for this therapy.