Assessment of Two Oscillating Positive Expiratory Pressure (OPEP) Devices: How do the Differing Mechanisms of Action Impact Lab Performance

OPEP devices are often used therapeutically in order to aid airway clearance where excess mucus is a challenge, such as in cystic fibrosis, bronchiectasis and chronic obstructive pulmonary disease. 

Real world differentiators for different types of OPEP devices include:

• Ease of use;
• Ability to clean, and;
• Adaptability to use with nebulizers.

The mechanism of action between devices can also differ, which is likely to result in different patient outcomes.

This laboratory study compared an established, clinically supported OPEP device with a recently introduced one that is based on older technology. Key in-vitro performance parameters were compared.

Devices Tested

• Aerobika* (Trudell Medical International, Canada) and
• AirPhysio† (AirPhysio, Australia) OPEP devices (n=3)

Test Set Up

Assessment performed at steady expiratory flows of 10-30L/min using a flow generator (Resmed VPAP III), flow meter (TSI 4000), pressure tap and computer for data collection and analysis.

Outcomes

Average positive pressure, pulse amplitude and pulse frequency were determined for each device.

For effective performance, oscillation frequency is typically desired to be in the 10-15 Hz range. This frequency range is optimal as it aligns with the cilia beat frequency (approximately 13 Hz) to support more efficient natural mucociliary clearance¹. The Aerobika* OPEP device exhibited frequencies more often in the desired range.

Moreover, therapeutic effectiveness is in part dependent on mean pressure ideally between 10-20 cm H20, with pulse (pressure) amplitude as large as possible. Higher amplitudes indicate greater changes in pressure differentials which can create stronger shear forces that reduce the viscoelastic properties of bronchial secretions,² enabling secretions to be cleared from the airways.³

Both devices exhibited similar average positive pressures, close to or within the desired range.

The Aerobika* OPEP device exhibited higher pressure amplitudes.

The results for the two devices show that although mean pressures are similar across the range of flow rates, the amplitudes are higher for the Aerobika* OPEP device, and the frequencies are often in the desired range, while they are not for the AirPhysio† device. The observed differences are probably due to the fact that each device operates according to a different mechanical principle.

These results show that it is important to understand that each OPEP device can perform different mechanically. All devices will not perform the same.

When selecting an OPEP device for a patient, real world usability assessments, as well as the existence of clinical evidence supporting efficacy should be considered.