When buying a Flutter or an Acapella, families usually have one main question: are these small vibrating devices really more effective than patting the patient's back, or better than the breathing exercises the physiotherapist teaches? For a family member with bronchiectasis or long-term heavy sputum, this is a practical question, because the devices are not cheap, they have to be used every day, and a wrong choice just ends up in a drawer.
The conclusion first. An oscillating PEP (positive expiratory pressure) device loosens secretions with expiratory resistance combined with airway vibration. The amount of sputum it clears is similar to, and not greater than,that of active breathing techniques such as the huff, and the evidence behind it is of low quality. The real value of the device is that it is easy to use, so the patient is willing to keep going. The principle of choice is therefore simple: choose a device that the patient is willing to take out and use every day, and learn the correct technique with a physiotherapist's guidance.
The most important thing is to choose a device the patient will use every day. In a randomised study of non-cystic fibrosis bronchiectasis, the amount of sputum cleared with Acapella and ACBT was not clearly different, but 14 of 20 people preferred the device (Patterson 2005). The Cochrane review also found no evidence that any one oscillating device, or any device compared with other physiotherapy methods, is more effective (Morrison 2020). Whether it works well does not depend on the brand, but on whether the patient keeps using it.
How oscillating PEP devices work
The working principle of an oscillating PEP device rests on two things, resistance and vibration. When the patient holds the mouthpiece and breathes out slowly and firmly, the parts inside the device (a steel ball in the Flutter, and a lever and magnet valve in the Acapella) open and close in a cycle. On one side this creates positive pressure on breathing out, which holds open the small airways that tend to collapse. On the other side it makes the airflow oscillate, which shakes loose secretions stuck to the airway wall. Once the secretions have loosened, a few forceful huffs push them up to the large airways so that they can be coughed up. This shows that these devices never work alone, and that "loosening by breathing out" must be combined with "clearing by huffing".
The idea that the device "shakes secretions loose" is in fact a reasonable inference from the design of the structure, together with clinical observations of short-term clearance, and is not a strong mechanism confirmed one by one in high-quality large trials. Understanding this explains why, in the comparison below, the gap between these devices and manual airway clearance techniques is not as large as might be imagined.
Oscillating PEP devices compared with ACBT
The question families ask most often is whether using a device is better than the breathing exercises taught by the therapist. The direct clinical evidence shows that devices are not more effective, but have a similar effect and are simpler to use.
- Weight of sputum cleared not significantly different from ACBT (mean difference 0.54 g; Patterson 2005)
- Preferred by most people: 14 of 20 chose the device (Patterson 2005)
- Brings its own vibration on breathing out, with no three-part cycle to remember, so it is easier to do alone
- Needs to be bought and cleaned, and the correct angle and resistance must be learned
- An equally effective clearance technique, and the comparison point for the more convenient alternative (Patterson 2005)
- No cost and no device, and can be done anywhere at any time
- The rhythm of three parts must be remembered: breathing control, thoracic expansion and the huff
- No worry about contamination from cleaning
The Cochrane review, after pooling several studies, reached the same conclusion: PEP therapy has an effect similar to other airway clearance techniques on quality of life, breathlessness, sputum clearance and lung volume. However, there were few studies, the overall quality of evidence was low, and long-term clinical benefit could not yet be established (Lee 2017). In other words, the existing data support the patient choosing a method that is comfortable to do and that can be kept up, and do not support the idea that a device must be used.
How to choose between Flutter and Acapella
Both devices work by expiratory resistance plus vibration, and the evidence does not show that either is better (Morrison 2020). Even when the Flutter was compared directly with another positive expiratory pressure device, the Lung Flute, there was no significant overall difference in the total sputum cleared. Participants only found the Flutter easier to master and use, so they slightly preferred it (Silva 2017). The focus of the choice is therefore not to compare specifications, but to judge which one is comfortable to use and easy to wash. The aspects to consider in practice are as follows:
| Posture and angle | The Flutter works by the gravity of the steel ball inside, and it must be held almost horizontal to produce vibration, so it is easier to use sitting upright. The Acapella has a magnet valve design and is less limited by angle. It can be used lying on the side or sitting semi-reclined, so it suits older adults who are bedbound or cannot sit up straight. |
| Adjusting resistance | The Acapella usually has a dial for adjusting the resistance, which makes it easy to raise or lower according to the degree of breathlessness. On the Flutter the resistance is changed mainly by fine adjustment of the angle at which it is held, so there is less room for adjustment. |
| Cleaning and hygiene | Both devices must be taken apart regularly, washed clean with water and dried, so that they do not go mouldy. The number of parts and the difficulty of taking them apart differ between models. Many patients give up halfway because washing is too much trouble, so it is best to ask a healthcare professional how to clean the device before buying it. |
| Cost and supply | These devices are self-paid consumables, and the price depends on the model. There is no need to look for an expensive brand. The most important thing is that the patient is used to it and the family can wash it easily every day. Buying an expensive device and leaving it in a drawer is of no use. |
How to use an oscillating PEP device correctly
Compared with the choice of device, correct technique has more effect on the result. The basic rhythm is to breathe out deeply and slowly to produce vibration, then huff at once to clear secretions, and to repeat this set by set:
- Sit well and hold the mouthpiece firmly—Sit upright and relax the shoulders and neck, with the lips sealed around the mouthpiece so that no air leaks. With a Flutter, remember to hold the device close to horizontal.
- Breathe out slowly and deeply with vibration—Take a breath in as usual, then breathe out slowly and firmly into the device. The patient should feel vibration in the chest. Breathing out like this 6 to 10 times counts as one set.
- Do 1 to 3 huffs—Put the device down and give a huff of medium force (a huff means breathing out with the mouth open, as if breathing onto a mirror), to push the loosened secretions up to the large airways to be coughed out. Remember not to cough hard and dry.
- Repeat for several sets and watch the response—Repeat the steps above until there is less sputum or the patient feels tired, and then stop. How many sets to do depends on the amount of sputum and the degree of breathlessness, and the physiotherapist will help to adjust this to the patient's condition.
The pattern above, 6 to 10 breaths per set with 1 to 3 huffs, is only a common reference in everyday clinical practice and is not a fixed prescription established by randomised trials. The suitable breath-out time, resistance and timing of the huff differ from person to person, so at first use it is advisable for a physiotherapist to demonstrate and calibrate on the spot.
Research evidence on oscillating PEP devices and its limits
In addition to explaining how to use the device, the limits should be stated first, so that patients and families do not have unrealistic expectations of it.
A device can help to clear secretions safely, but it cannot cure the disease. The Cochrane review found that for patients with stable bronchiectasis, airway clearance techniques are safe and may help to clear secretions and improve some lung function measures and symptoms, but they do not appear to reduce exacerbations, and the quality of the related research evidence is generally low (Lee 2015). A review of cystic fibrosis also showed that oscillating devices are overall neither better nor worse than other physiotherapy, that patient preferences differ, and that the quality of evidence is low to very low (Morrison 2020). For patients with pneumonia alone, chest physiotherapy (including PEP) has not been shown to improve mortality or cure rate, with very low certainty of evidence (Chen 2022). The device should therefore be seen as a safe, short-term tool for helping to clear secretions, and not as a way to cure disease, reduce hospital admissions or prevent infection.
Points to note and when to see a professional for assessment
The precondition for using an oscillating PEP device is that the patient has a certain ability to breathe out and cough. If the cough is too weak, such a device alone may not clear secretions, and other assistive methods must be used.
- If the peak cough flow is below 270 L/min (for example in more severe neuromuscular disease), clinical guidelines advise using cough assistance techniques, and the patient should not rely on an oscillating PEP device alone (AARC 2013).
- If there is an untreated pneumothorax, the patient is coughing up blood, or there is a serious and unstable cardiovascular problem, a healthcare professional must be asked first. The device should not be used without assessment.
- If there is fever, the sputum changes colour or the breathlessness clearly worsens, the patient should see a doctor promptly, because the device can only help to clear secretions and cannot treat the illness.
- If the patient can follow instructions and has enough strength to breathe out, and the main problem is bronchiectasis or long-term heavy sputum, such a device is generally suitable for daily care.
- At first use, or when changing to a new model, a physiotherapist should first measure cough strength and demonstrate in person how to use the device and set the resistance, and only then should the patient use it alone at home.
It is worth noting that for the advanced cough assistance machines used in neuromuscular disease, such as mechanical insufflation-exsufflation (MI-E), the existing evidence is still not enough to support or oppose routine use (Morrow 2013). Changing the plan therefore does not mean switching to a machine that is bound to work. It means moving to a model of professional assessment and care that better suits people with a weak cough, and this step must be judged by healthcare professionals. To learn first about cough strength as a key marker, and where the 270 L/min dividing line comes from, read the overview of airway clearance and chest percussion techniques. For choosing a daily airway clearance plan for older adults with bronchiectasis, see the page on long-term care in bronchiectasis.
Practising at home and local sources of support
Because living spaces in Hong Kong are generally small, a compact oscillating PEP device is quite practical. An older adult only needs to sit at the dining table with both elbows resting lightly on it to complete a set of breath-out vibration exercises. For bedbound older adults with limited mobility who need to lie on the side or sit semi-reclined, the Acapella, which is less limited by angle, is the most convenient. After each use the device should be taken apart at once, washed in water and left to dry, to prevent mould growing in Hong Kong's humid weather. Good cleaning and maintenance matter as much as which device is chosen.
At the first home assessment by a physiotherapist, the question family members ask most often is which device is better. What really needs to be understood first, however, is the older adult's ability to sit and their hand coordination. Those who can sit upright and coordinate mouth and hand well can consider a Flutter, and those who need to sit semi-reclined, lie on the side or adjust the resistance suit an Acapella better. The principle is always to assess the patient's condition first and choose a suitable device afterwards. The therapist also reminds family members that the effect of airway clearance depends on keeping it up every day and not on buying an expensive device, and demonstrates the cleaning steps on the spot so that the family can help the older adult practise independently later. With the home physiotherapy serviceprovided by registered physiotherapists at Nova Health, the therapist measures the patient's cough strength, guides the correct rhythm of breathe out, vibration and huff, and teaches family members everyday airway clearance skills. The public can also make use of the following local community and learning resources:
Local learning and support resources. The Hong Kong Society for Rehabilitation community rehabilitation network (香港復康會社區復康網絡) has a team of social workers, physiotherapists, occupational therapists and nurses who support people with long-term illness and carers (康山中心, telephone 2549 7744). To learn more about the condition, see the public education resources on bronchiectasis from the Hong Kong Thoracic Society (hkts.hk). The patient resources and the list of patient self-help organisations on the Hospital Authority's 智友站 (ha.org.hk) also contain much practical information.