The Importance of Expiratory Flow Bias in Secretion Clearance

A published study challenges the traditional focus on pressure amplitude as an indicator of the effectiveness of OPEP therapy. Instead of focusing on pressure, the study analyzed maximum expiratory flow during OPEP therapy by comparing flow-volume loops generated by the vPEP against two competitive products during simulated, spontaneous breathing. The study found that, just as in a forced cough, peak expiratory flow is a major factor in improving secretion clearance with OPEP devices.

Expiratory Flow Bias is also important. This is the difference between peak expiratory flow and peak inspiratory flow. Secretion clearance increases when maximum expiratory flow exceeds maximum inspiratory flow during OPEP therapy. The greater the difference, the more effective the secretion clearance, and vice versa. The vPEP provides a superior flow rate difference across five tidal volumes when compared to two competitive products. Charts 1-2 show a bench study using a human lung simulator at various breath sizes with OPEP products at low and high resistance settings.

View video - secretion clearance


Maximizing the Expiratory Flow Bias (VE max - VI max diffference)

Difference at Low Resistance
Difference at High Resistance

Reference: Pursley, D.M., Analysis of Three Oscillating Positive Expiratory Pressure Devices During Simulated Breathing. Respiratory Therapy 2017; Volume 12, No. 1, 52-56.

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