Timing of EFL Treatment in Patients using a Non-Invasive Ventilator

Rationale: The Forced Oscillation Technique (FOT) at 2 cmH2O at 5 hz measures ∆Xrs, displays an index of the Expiratory Flow Limitation (EFL) (∆Xrs >= 2.8 cmH2O/L/s) and adjusts EPAP to abolish EFL. The pressures at which EFL is abolished and needed to maintain abolishment and that timing has not been previously studied. Methods: This study used an unreleased, modified ventilator (BiPAP A40, Philips/Respironics, Monroeville, PA) with FOT. Twelve NIV-naive subjects, with COPD, were screened for EFL. One subject participated twice. Six subjects exhibited EFL and underwent a 20-minute therapy session starting at 4 cmH2O with a fixed pressure support of 6 cmH2O and FOT oscillations in S/T mode. An auto-titrated EPAP was applied during the session. Results: A summary of the data from the titration sessions is presented in Table 1. All subjects reached an EPAP needed to abolish EFL within the 20-minute period. That average maximum pressure was 11.6 cmH2O (7.3 – 18.1). Once max EPAP was reached, all subjects required a lesser EPAP pressure to maintain abolishment. The average pressure to maintain abolishment across all participants was 10.8 cmH2O (5.6 – 16.9). Conclusions: Therapy can be implemented in a non-invasive ventilator to determine EPAP pressure to abolish EFL and maintain therapy at optimal pressure to maintain abolishment. Early pilot data reflects that EFL can be abolished quickly and maintained throughout the night during variability of sleep