| Popis: |
Rationale: This study used an unreleased modified noninvasive ventilator (BiPAP A40EFL, Philips/Respironics, Monroeville, PA) with the Forced Oscillation Technique (FOT) and the method of Dellaca et al (2004) to dynamically measure ∆Xrs, which then adjusts the EPAP (PEEPopt) setting to abolish Expiratory Flow Limitation (EFL). Methods: A population of COPD, both NIV Naive and hypercapnic NIV users, were screened for EFL.Out of Nine (9) participants with EFL, eight were studied via Overnight Polysomnography. One did not meet inclusion criteria. The Ventilator used S/T mode with auto-titrating EPAP to abolish EFL (PEEPopt), with a min EPAP of 4 cmH20 and a fixed PS of 6 cmH2O. Results: The patient behaviors were highlighted with a “transition” filter, looking for a change of >2cm over a tuned moving window. These transitions are highlighted with red overlays: Patients separated into two classes: with large or small pressure swings. Four patients have large swings (A, D, F, and H), four have small (B, C, E and G). The patient separations are clear via the histograms which graph EPAP changes. A demarcation of 6cm change is evident. Conclusion: The EFL algorithm worked as desired. The data reveal two patient classes. One needed relatively low EPAP and small adjustments to abolish EFL, the other required a higher average EPAP and a much larger adjustment during the night. EFL in both cases seems well-managed by the algorithm as indicated by the ∆Xrs value. |
