Tracking severity and distribution of lung disease during mechanical ventilation: applications to bronchoconstriction and respiratory distress syndrome

We developed an Enhanced Ventilator Waveform (EVW) on an NPB840 ventilator that contains discrete frequencies blended to provide a tidal breath followed by passive exhalation. Unique signal processing provides estimates of inspiratory resistance (R) and elastance (E) from 0.1 to 8 Hz. Such data are sensitive to the pattern of lung disease. We applied the EVW in 5 sheep before and after a bronchial challenge and an oleic acid respiratory distress syndrome (RDS) model. In all sheep, the EVW provided clinically effective ventilation during and after bronchoconstriction, as well as during RDS. Data revealed a range of constriction conditions from mild to severe and heterogeneous with airway closures. Strong correlations were found between the degradation of blood gases and increasing disease state as measured by the EVW. We conclude that the EVW is a viable new ventilation method that can provide clinically unique information during acute and chronic lung distress.