Flutter device interventions
Study	Intervention	Frequency
Gondor 1999	Flutter device treatments, supervised by an RT immediately after prescribed bronchodilator therapy. Sitting position with head raised so that the stem of the device was parallel to the floor, placing the cone at a slight tilt away from the participant. After inhaling and holding their breath for 2–3 seconds, participants would slowly exhale through the Flutter valve, causing oscillations of the steel ball inside the cone of the Flutter device. After each series of exhalations, participants were instructed to "huff" and cough, thereby aiding expectoration.	4 times daily. 3 sets of 15 exhalations performed over 12–20 minutes.
Homnick 1998	Albuterol nebuliser (2.5–5 mg) in either 2 mL normal saline solution or 20 mg (2 mL) cromolyn sodium. Supervised Flutter therapy during hospitalisation administered by registered and trained RTs using manufacturer's recommendations.	4 times daily. Each session lasted 15 minutes.
Sontag 2010	Self‐administered Flutter device (Scandipharm, Birmingham, Alabama), incorporating Flutter device airway vibration and FET with coughing. Flutter treatment divided into 3 stages: loosening and mobilisation breaths, followed by mucus mobilisation and expectoration.	Twice daily. Each session 20–40 minutes.