The use of vibrating devices to help people with cystic fibrosis clear their airways of mucus

Review question

We reviewed the evidence about the effect of vibrating devices (e.g. Flutter, acapella, cornet, Quake®, intrapulmonary percussive ventilation, high frequency chest wall oscillators (e.g. Vest®), VibraLung®, MetaNeb®, and Aerobika® to help people with cystic fibrosis clear their airways of mucus. This is an update of a previously published review.


People with cystic fibrosis have too much sticky mucus in their lungs which can lead to constant infection and inflammation. This damages their airways and worsens lung function over time. People with cystic fibrosis use chest physiotherapy to clear the mucus from their lungs. They can use different methods alone or in combination with others - manual techniques, breathing techniques and mechanical devices. Vibrating devices (also sometimes known as oscillators) use pressure generated either inside or outside of the body to clear the mucus.

Search date

Evidence is current to 29 July 2019.

Study characteristics

The review included 39 studies with 1114 people with cystic fibrosis aged between 4 and 63 years of age. Studies compared different physiotherapy treatments and people were selected for one treatment or the other randomly. Not many studies looked at the same types of physiotherapy over the same period of time; studies ranged in duration from two days to 13 months.

Key results

Given the differences in study design, it was difficult to combine the results from these studies in a useful way.

We did not find any clear evidence that vibrating devices were better than any other form of physiotherapy which they were compared to in these studies, or that one device was better than another. One study found that people using an vibrating device needed additional antibiotics for a chest infection more often than those using positive expiratory pressure. When recommending the most suitable method of airway clearance, physiotherapists should consider the needs of the people they are treating.

For the future, larger and longer trials are needed to measure the frequency of lung infections, preference, adherence to and general satisfaction with treatment, financial constraints should also be taken into consideration. We think adherence is important, because if people with cystic fibrosis are willing to stick to their physiotherapy regimen, there may be improvements in other outcomes such as exercise tolerance, respiratory function and mortality.

Quality of the evidence

Overall, we thought most studies had some design problems which might affect our confidence in some of the results. In about a quarter of studies there were concerns that not all the results were reported clearly and in about a third of the studies the reasons for people withdrawing from a trial were not clearly explained. In comparisons of different types of physiotherapy, a person and their physiotherapist will always know which treatment they are receiving and this might affect their answers to some questions, such as which treatment makes them feel better, but we only thought this was a problem in a few studies. We used a scoring system called GRADE to assess the quality of the evidence, we then judged it to be either low- or very low-quality, which suggests that further research is very likely to affect our confidence in the results in this review for of any of the interventions analysed.

Authors' conclusions: 

There was no clear evidence that oscillation was a more or less effective intervention overall than other forms of physiotherapy; furthermore there was no evidence that one device is superior to another. The findings from one study showing an increase in frequency of exacerbations requiring antibiotics whilst using an oscillating device compared to positive expiratory pressure may have significant resource implications. More adequately-powered long-term randomised controlled trials are necessary and outcomes measured should include frequency of exacerbations, individual preference, adherence to therapy and general satisfaction with treatment. Increased adherence to therapy may then lead to improvements in other parameters, such as exercise tolerance and respiratory function. Additional evidence is needed to evaluate whether oscillating devices combined with other forms of airway clearance is efficacious in people with cystic fibrosis.There may also be a requirement to consider the cost implication of devices over other forms of equally advantageous airway clearance techniques. Using the GRADE method to assess the quality of the evidence, we judged this to be low or very low quality, which suggests that further research is very likely to have an impact on confidence in any estimate of effect generated by future interventions.

Read the full abstract...

Chest physiotherapy is widely prescribed to assist the clearance of airway secretions in people with cystic fibrosis. Oscillating devices generate intra- or extra-thoracic oscillations orally or external to the chest wall. Internally they create variable resistances within the airways, generating controlled oscillating positive pressure which mobilises mucus. Extra-thoracic oscillations are generated by forces outside the respiratory system, e.g. high frequency chest wall oscillation. This is an update of a previously published review.


To identify whether oscillatory devices, oral or chest wall, are effective for mucociliary clearance and whether they are equivalent or superior to other forms of airway clearance in the successful management of secretions in people with cystic fibrosis.

Search strategy: 

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register comprising references identified from comprehensive electronic database searches and hand searches of relevant journals and abstract books of conference proceedings. Latest search of the Cystic Fibrosis Trials Register: 29 July 2019.

In addition we searched the trials databases and the WHO International Clinical Trials Registry Platform. Latest search of trials databases: 15 August 2019.

Selection criteria: 

Randomised controlled studies and controlled clinical studies of oscillating devices compared with any other form of physiotherapy in people with cystic fibrosis. Single-treatment interventions (therapy technique used only once in the comparison) were excluded.

Data collection and analysis: 

Two authors independently applied the inclusion criteria to publications, assessed the quality of the included studies and assessed the evidence using GRADE.

Main results: 

The searches identified 82 studies (330 references); 39 studies (total of 1114 participants) met the inclusion criteria. Studies varied in duration from up to one week to one year; 20 of the studies were cross-over in design. The studies also varied in type of intervention and the outcomes measured, data were not published in sufficient detail in most of these studies, so meta-analysis was limited. Few studies were considered to have a low risk of bias in any domain. It is not possible to blind participants and clinicians to physiotherapy interventions, but 13 studies did blind the outcome assessors. The quality of the evidence across all comparisons ranged from low to very low.

Forced expiratory volume in one second was the most frequently measured outcome and while many of the studies reported an improvement in those people using a vibrating device compared to before the study, there were few differences when comparing the different devices to each other or to other airway clearance techniques. One study identified an increase in frequency of exacerbations requiring antibiotics whilst using high frequency chest wall oscillation when compared to positive expiratory pressure (low-quality evidence). There were some small but significant changes in secondary outcome variables such as sputum volume or weight, but not wholly in favour of oscillating devices and due to the low- or very low-quality evidence, it is not clear whether these were due to the particular intervention. Participant satisfaction was reported in 13 studies but again with low- or very low-quality evidence and not consistently in favour of an oscillating device, as some participants preferred breathing techniques or techniques used prior to the study interventions. The results for the remaining outcome measures were not examined or reported in sufficient detail to provide any high-level evidence.