46 The resultant positive pressure varies with the resistance setting. The Pari PEP S consists of a 1-way valve that allows unrestricted inspiration and a resistance to expiration through a fixed (but interchangeable) resistor valve to produce positive airway pressure. The study had 2 aims: first, to compare mean pressure, peak pressure, amplitude of pressure variation, and oscillation frequency of different devices across a range of flows at a fixed resistance setting and second, to compare the mean pressure, peak pressure, amplitude of pressure variation, and oscillation frequency of different devices across a range of resistance settings at a fixed flow. The purpose of our study was to compare the performance characteristics (ie, mean PEP, peak PEP, amplitude PEP, and oscillation frequency) of 6 commonly used airway clearance devices: Pari PEP S (Pari, Starnberg, Germany), Flutter (Axcan Scandipharm, Birmingham, Alabama), Acapella Choice (DHD Healthcare, Wampsville, New York), Acapella DM (DHD Healthcare), Acapella DH (DHD Healthcare), and Aerobika (Trudell Medical International, Ontario, Canada). 13, 42, 43 Despite claims made by manufacturers that their PEP devices perform across a range of flows and resistance settings, the effectiveness of PEP varies in relation to device setting 44 and flow it is therefore important to clarify the differences in the PEP and oscillations generated by different devices when resistance and flow are varied. As a result, the efficacy of airway clearance techniques remains unclear. This ambiguity is the result of heterogeneity in study methodologies and outcome measures used to define the effectiveness of different devices. While international guidelines recommend airway clearance techniques, 17, 37– 41 currently there are no definitive studies or guidelines on the preference or superiority of one airway clearance technique compared to another. 28, 29 The oscillatory devices aim to approximate cilial movement frequency and pulmonary resonance frequency of 11–15 Hz in adults 30– 36 to optimize expectoration. 21– 25 Oscillatory PEP offers the combination of PEP and airway oscillations to alter rheology of secretions 12, 26, 27 and improve secretion transport 12 higher oscillation amplitudes reportedly increase the effectiveness of therapy. 18, 19 Studies suggest PEP stabilizes and splints airways open, 19– 21 and increases intrathoracic pressure distal to retained sections to facilitate movement of secretions centrally for expectoration. The addition of positive pressure during prolonged expiration increases expiratory capacity and has been shown to reduce gas trapping. 14– 16 A number of airway clearance techniques are applied in clinical practice including the application of positive expiratory pressure (PEP) devices. Airway clearance techniques are applied by clinicians to facilitate secretion removal, 10– 12 optimize respiratory status 13 and improve health-related quality of life. 3 Clinically, chronic cough and excess sputum production are associated with exacerbations 4– 7 in COPD and cystic fibrosis, hospitalization 6 in COPD, declining respiratory function, 8 and increased mortality 9 in non–cystic fibrosis bronchiectasis. 1, 2 Impaired mucociliary clearance and airway mucus hypersecretion are pathological features of many chronic lung diseases. Mucociliary clearance is an essential mechanism of lung defense, enabling the efficient clearance of inhaled particles and pathogens from the respiratory system. Amplitude PEP was either maintained or increased during oscillations when increasing resistance for all devices except the Flutter. Increasing resistance either maintained or increased oscillation frequency for all devices. Increasing resistance increased peak PEP produced by the Acapella DM, Aerobika, and Pari PEP S but resulted in minimal change in peak PEP for the Flutter and Acapella Choice. At a fixed flow, increasing resistance increased mean PEP produced by all devices except the Acapella Choice. Increasing flow maintained or increased oscillation frequency for all devices except the Flutter. Increasing flow increased peak PEP and amplitude PEP produced by all devices except the Acapella DH and Acapella Choice. Increasing flow resulted in minimal change in mean PEP produced by the Flutter and Acapella DM. At a fixed resistance, increasing flows increased mean PEP produced by the Acapella Choice, Acapella DH, Aerobika, and Pari PEP S. RESULTS: Performance characteristics of the devices differed across flows and resistance settings (device × flow/resistance interaction P <.
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