Regional Distribution Differences Between Neurally Adjusted Ventilatory Assist and Pressure Support Ventilation

Neurally adjusted ventilatory assist (NAVA) is an FDA approved mode of mechanical
ventilation. This mode of ventilation is currently in routine use in adult, pediatric and
neonatal intensive care units. The electrical activity of the diaphragm, the largest muscle
used during inspiration, is measured. The ventilator triggers (synchronizes patient effort)
and applies proportional assistance based on measured electrical activity of the diaphragm
(Edi). This electrical activity is measured through a feeding tube that also has a
multiple-array esophageal electrode in it. This mode of ventilation has been proven to be
equivalent to pressure support ventilation (PSV). Theoretically, the breath-to-breath control
offered by NAVA may not only trigger faster and synchronize better, but provide the support
deemed appropriate by the central nervous center on demand. Traditionally in the intensive
care unit (ICU), pressure support is applied to subject breathing spontaneously. Pressure is
set to achieve a given tidal volume. The influence of changing lung compliance not only from
the lung disease itself, but the interactions of the respiratory muscles can drastically
change minute ventilation and contribute to hyper- or hypoventilation. These changes are
typically found on assessment of end-tidal carbon dioxide (CO2), blood gas, or oxygen
saturation (SpO2) monitoring; all of which are potentially preventable if we allowed the
central nervous system to control the ventilator. NAVA may allow us to couple the central
nervous system (neuro-coupling) with the ventilator to provide real-time proportional
assistance, reduce work of breathing and apply physiologic breathing patterns.