Mechanical comparison of 6 oscillatory positive expiratory pressure devices.

Abstract

Background: Many oscillatory positive expiratory pressure (OPEP) devices exist and some of them use unique mechanism to produce air-flow oscillations. However their operational parameters and elicited therapeutic effects may vary. Objectives: To assess the mechanical performance of 6 OPEP devices at different resistance levels. Methods: Four gravity-dependent (Flutter, Gelomuc, Shaker, PARI-OPEP) and 2 gravity-independent OPEP devices (Acapella Choice and Aerobika) were tested at 3 resistance levels (low, medium, high). Each device was independently attached to an artificial lung driven by a ventilator in order to simulate an active exhalation. Ventilator settings were adjusted to produce peak expiratory flow rate between 40-45 L.min-1 at 10 breaths.min-1. The middle-third of the exhalation phase was used to compare positive expiratory pressure (PEP), oscillatory frequency (OF) and pressure amplitude (PA). Optimal operational parameters were defined as OFs of 12 Hz or above and PEP ranging between 10-20 cmH2O. Corresponding PAs at these settings were analysed. Results: Only gravity-dependent devices at medium and high resistance levels produced the desired OFs and PEP settings, ranging from 16 to 22 Hz and 12 to 18 cmH2O, respectively. Corresponding PAs ranged from 0.6 to 1.8 cmH2O. Compared to these devices, Acapella and Aerobika elicited higher PAs (from 1.7 to 4.2 cmH2O) although they did not achieve optimal PEP or OF parameters. Conclusions: The gravity-dependent devices displayed close mechanical performances and produced optimal operational parameters at the simulated exhalation settings. Acapella and Aerobika probably require higher expiratory pressure to reach theoretical therapeutic effectiveness.