Optimal mean airway pressure during high-frequency oscillatory ventilation determined by measurement of respiratory system reactance

Background: The aims of the present study were (i) to characterize the relationship between mean airway pressure (PAW) and reactance measured at 5 Hz (reactance of the respiratory system (XRS), forced oscillation technique) and (ii) to compare optimal PAW (P opt) defined by XRS, oxygenation, lung volume (V L), and tidal volume (VT) in preterm lambs receiving high-frequency oscillatory ventilation (HFOV). Methods: Nine 132-d gestation lambs were commenced on HFOV at PAW of 14 cmH2O (P start). PAW was increased stepwise to a maximum pressure (Pmax) and subsequently sequentially decreased to the closing pressure (Pcl, oxygenation deteriorated) or a minimum of 6 cmH 2O, using an oxygenation-based recruitment maneuver. XRS, regional VL (electrical impedance tomography), and VT were measured immediately after (t 0min) and 2 min after (t 2min) each P AW decrement. Popt defined by oxygenation, XRS, VL, and VT were determined. Results: The P AW-XRS and PAW-VT relationships were dome shaped with a maximum at Pcl +6 cmH2O, the same point as Popt defined by VL. Below Pcl+6 cmH2O, XRS became unstable between t0min and t2min and was associated with derecruitment in the dependent lung. Popt, as defined by oxygenation, was lower than the Popt defined by XRS, VL, or VT. Conclusion: X RS has the potential as a bedside tool for optimizing PAW during HFOV. Copyright © 2014 International Pediatric Research Foundation, Inc.