Accuracy of the dynamic signal analysis approach in respiratory mechanics during noninvasive pressure support ventilation: a bench study

Abstract

Objective To evaluate the accuracy of respiratory mechanics using dynamic signal analysis during noninvasive pressure support ventilation (PSV). Methods A Respironics V60 ventilator was connected to an active lung simulator to model normal, restrictive, obstructive, and mixed obstructive and restrictive profiles. The PSV was adjusted to maintain tidal volumes (VT) that achieved 5.0, 7.0, and 10.0 mL/kg body weight, and the positive end-expiration pressure (PEEP) was set to 5 cmH2O. Ventilator performance was evaluated by measuring the flow, airway pressure, and volume. The system compliance (Crs) and airway resistance (inspiratory and expiratory resistance, Rinsp and Rexp, respectively) were calculated. Results Under active breathing conditions, the Crs was overestimated in the normal and restrictive models, and it decreased with an increasing pressure support (PS) level. The Rinsp calculated error was approximately 10% at 10.0 mL/kg of VT, and similar results were obtained for the calculated Rexp at 7.0 mL/kg of VT. Conclusion Using dynamic signal analysis, appropriate tidal volume was beneficial for Rrs, especially for estimating Rexp during assisted ventilation. The Crs measurement was also relatively accurate in obstructive conditions.

Continuous estimation of respiratory system compliance and airway resistance during pressure-controlled ventilation without end-inspiration occlusion

“…In this bench study, the dynamic signal analysis approach was used to collect and calculate gas flow, airway pressure, and volume data at different time points during mechanical ventilation, and the estimated C rs , R insp , and R exp were calibrated by virtual extrapolation of V T when end-inspiration flow was not zero. Dynamic signal analysis does not require special maneuvers such as long-time pauses at the inspiration or expiration phase [ 26 ]. In healthy adults and mild obstruction lung models, no significant differences were found in estimated C rs and R aw (R insp and R exp ) between the PCV and VCV modes with EIF < 2.0 L/min and EIF/PIF% < 5.0%.…”

“…Such an approach improves estimation precision in respiratory system mechanics via real-time collection of respiratory data from the inspiration and expiration phases by applying specific Eqs. [ 25 , 26 ]. C st and R aw measurements based on the end-inspiratory occlusion maneuver in the real clinical setting were considered the gold standard for the validation of the proposed approach.…”