title: Pressures and Oscillation Frequencies Generated by Bubble-Positive Expiratory Pressure Devices.
abstract: BACKGROUND
  Positive expiratory pressure (PEP) devices are used to assist with airway clearance. Little is known about the therapist-made or commercially available bubble-PEP devices. The aim of this study was to determine the end-expiratory pressures (cm H2O) and oscillation frequencies (Hz) generated when a range of flows were applied to the therapist-made bubble-PEP devices (Bubble-PEP-3cm and Bubble-PEP-0cm) and commercial bubble-PEP devices (AguaPEP, Hydrapep, and Therabubble).
  
  
  METHODS
  This was a bench-top experimental study using a compressed air source, flow rotameter (flows of 5, 10, 15, 20, and 25 L/min), and pressure transducer. Data were collected using a data acquisition device with PhysioDAQxs software and analyzed with Breathalyser software to determine the pressures and oscillation frequencies generated by 5 bubble-PEP devices. Each flow was constant for a 30-s measurement period, and measurements were repeated in triplicate. The 5 devices were: a therapist-made Bubble-PEP-3cm device (filled with 13 cm of water, tubing resting 3 cm from the base of the container); the therapist-made Bubble-PEP-0cm (filled with 10 cm of water, tubing resting at the base of the container); and the AguaPEP, Hydrapep, and Therabubble devices with water to the 10 cm mark on the containers.
  
  
  RESULTS
  Flows of 5-25 L/min produced the following mean ± SD PEP and oscillation frequencies (Hz): the Bubble-PEP-3cm produced PEP of 10.4 ± 0.14 to 10.8 ± 0.24 cm H2O, oscillations between 13 and 17 Hz; the Bubble-PEP-0cm produced PEP of 10.9 ± 0.01 to 12.9 ± 0.08 cm H2O, oscillations between 12 and 14 Hz; the AguaPEP produced PEP from 9.7 ± 0.02 to 11.5 ± 0.02 cm H2O, oscillations between 11 and 17 Hz; the Hydrapep produced PEP of 9.6 ± 0.35 to 10.7 ± 0.39 cm H2O, oscillations between 14 and 17 Hz; and the Therabubble produced PEP from 8.6 ± 0.01 to 12.8 ± 0.03 cm H2O, oscillations between 14 and 17 Hz.
  
  
  CONCLUSIONS
  Bubble-PEP-3cm maintained the most stable pressure throughout the range of flows tested. All devices investigated produced similar oscillation frequencies.
authors.affiliation: Clinical and Rehabilitation Sciences, University of Sydney, Lidcombe, New South Wales 2141, Australia. mary.santos@health.nsw.gov.au.|Department of Physiotherapy, Prince of Wales Hospital, Barker Street, Randwick, New South Wales 2031, Australia.
authors.forename: Mary D
authors.initials: MD
authors.lastname: Santos
authors.affiliation: Clinical and Rehabilitation Sciences, University of Sydney, Lidcombe, New South Wales 2141, Australia.
authors.forename: Maree A
authors.initials: MA
authors.lastname: Milross
authors.affiliation: Clinical and Rehabilitation Sciences, University of Sydney, Lidcombe, New South Wales 2141, Australia.
authors.forename: John P
authors.initials: JP
authors.lastname: Eisenhuth
authors.affiliation: Clinical and Rehabilitation Sciences, University of Sydney, Lidcombe, New South Wales 2141, Australia.|Department of Physiotherapy, Royal Prince Alfred Hospital, Missenden Road, Camperdown, New South Wales 2050, Australia.
authors.forename: Jennifer A
authors.initials: JA
authors.lastname: Alison
mesh_terms: D001944:Breath Tests / Q000295:instrumentation / Q000379:methods; D035641:Chest Wall Oscillation / Q000295:instrumentation*; D004867:Equipment Design; D006801:Humans; D008422:Materials Testing / Q000379:methods*; D011175:Positive-Pressure Respiration / Q000295:instrumentation*; D011312:Pressure; D012123:Pulmonary Ventilation; D012984:Software
keywords: AguaPEP; Hydrapep; Therabubble; airway clearance; bubble; physiotherapy; positive expiratory pressure device; therapist-made