Effects of Different Breathing Patterns in Two Percussive Secretion Mobilization Devices

Abstract

Background: A variety of pulmonary conditions can lead to increased mucus production that can become tenacious and difficult to mobilize. Percussive devices such as the Intrapulmonary Percussive Ventilator (IPV) (Model-2C, Percussionaire Sandpoint, ID) and MetaNeb system (Hill-Rom, St. Paul, MN) are marketed as devices that assist in mobilizing secretions. The purpose of this study is to determine if coaching patients to achieve a specific I:E ratio will assist in secretion mobilization while using these devices. Methods: The Ingmar Medical ASL 5000 (Pittsburgh, PA) was used to simulate a spontaneous breathing patient with active exhalation. The simulator was programmed with a compliance of 60 mL/cm H₂O, resistance of 18 cm H₂O/L/s to represent chronic bronchitis, with a tidal volume of 800 mL and a respiratory rate of 15. Three I:E ratios were used to represent different breathing patterns: 1:3 (normal spontaneous breathing), 3:1 (inverse), and 1:1 (equal). Both IPV and MetaNeb were used for testing. Each device was tested on its high frequency and low frequency settings. For the mucous simulant, 100 mL of locust bean gum solution (1.9 g LBG/500 mL Water) was mixed with 3 mL of sodium tetraborate solution (8 g Tetraborate/1 L water). A 33.2 cm long section Tygon tubing with an internal diameter of 13 mm was used to simulate the trachea. For each trial, 1 mL of mucous simulant was injected into the middle of the tubing. Each I:E ratio and frequency setting was performed in triplicate. The velocity was calculated in centimeters per minute (cm/min) using picture analysis on ImageJ software (National Institute of Health, Bethesda, MD). Results: There was no difference in mucous velocity between devices (P = .53) or frequency setting (P = .38). There was, however, a significant difference in mucous velocity between I:E ratios, with the largest difference occurring between a ratio of 3:1 and 1:1 (P = <.001). The average mucous velocities were 4.0, 1.45, and -0.06 (cm/min) at I:E ratios of 3:1, 1:1 and 1:3 respectively. Conclusions: This study demonstrated an increase in mucous movement when instructing a patient to achieve an I:E ratio of 3:1 while performing these therapies. Clinical follow-up is needed to determine if instructing patients to perform a long inspiratory phase, followed by a short, forceful exhalation, improves secretion movement while performing these therapies.

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