EPAP variability during EFL Treatment in Patients using a Non-Invasive Ventilator

Rationale: Expiratory Flow Limitation (EFL) in patients with COPD can present challenges when assisting ventilation. To overcome EFL during ventilation, EPAP is applied. The current study was undertaken to explore the variability of EFL determined using Forced Oscillation Technique (FOT) and the method of Dellaca et al (2004) to dynamically measure ∆Xrs and then automatically adjust EPAP (PEEPopt). Methods: An unreleased noninvasive ventilator (BiPAP A40, Philips Respironics, USA) set in an S/T mode was used. Seven participants used the device for 2-weeks at home. The device auto-titrated EPAP (range 4 – 20 cmH2O) to abolish EFL and delivered a fixed Pressure Support of 6 cmH2O. Device data were analyzed to determine the variability of PEEPopt. Results: Demographic and device data are found in Table 1. The variability in EPAP is seen by the differences between the mean EPAP ((mean± SD) 6.5 ± 0.9 cmH2O), the 90% EPAP (9.2 ± 3.6 cmH2O), and the maximum EPAP (11.8 ± 3.7 cmH2O). Variability in an individual patient is illustrated in Table 2, where the average EPAP (5.6) is 65% of the 90% EPAP (8.6). Conclusions: The FOT method to assess EFL illustrates the variability of flow limitation over a two-week period. Using a single expiratory pressure to eliminate EFL may be sub-optimal. A continuous auto-titrating method to determine PEEPopt to treat variable EFL may be helpful when providing non-invasive ventilation to patients with COPD.