Conventional mechanical ventilators sense a patient effort by either a drop in airway pressure or a reversal in flow. The last and most slow reacting step in the chain of respiratory events is used to sense the patient effort. Hence, creating a system that is sensitive to hyperinflation, intrinsic PEEP and secondary triggering problems.
With NAVA, the electrical activity of the diaphragm (Edi) is captured, fed to the ventilator and used to assist the patient’s breathing.
Rather than sensing negative pressure or flow to trigger a breath the system senses neural traffic. This has the potential to markedly decrease work of breathing and fatigue. To avoid diaphragmatic disuse the level of support with each breath can be varied. The sensor is apparently an adaption of an NG tube. More systematic study will be necessary to determine its precise role.