Mouth pressures during pursed lip breathing

Abstract

Breathing with positive expiratory pressure (PEP), such as pursed lip breathing (PLB), is a therapeutic intervention for patients with obstructive lung disease. The effects of PEP breathing are thought to be based on the amount of the applied oral pressure. The purpose of this study was to compare oral pressures during PLB with those during other forms of PEP breathing, in order to establish the best artificial replacement for the expiratory pressures reached during PLB.Oral pressure was measured during PLB, during breathing with an expiratory threshold valve of 5 cm H2O (PEP5) and during expiration through tubes of diameter 2, 3 and 5 mm. The study group comprised 16 healthy subjects and 8 patients with chronic obstructive pulmonary disease. We found that during PLB, a peak expiratory pressure of about 5 cm H2O is reached. This is comparable to breathing with a PEP threshold valve of 5 cm H2O. Based on these results, we recommend a flow-independent threshold valve in order to simulate the expiratory pressure induced by PLB.