Improving Outcome Measures For Adult CF ACT Trials

  • Research type

    Research Study

  • Full title

    Improving Outcome Measures For Physiotherapy Trials of Airway Clearance in Adults with Cystic Fibrosis



  • Contact name

    Gemma E Stanford

  • Contact email

  • Sponsor organisation

    Royal Brompton and Harefield NHS Foundation Trust

  • Identifier


  • Duration of Study in the UK

    4 years, 8 months, 0 days

  • Research summary

    Research Summary
    Airway clearance techniques (ACTs) to clear sputum are key to cystic fibrosis (CF) management. There is no consensus as to which ACT is most effective as there is no accepted robust outcome to measure this. This research will compare historical outcome measures (sputum weight and FEV1) against new measures (electrical impedance tomography, lung clearance index, impulse oscillometry) investigating if there is a more scientific measure of ACT effect. This is essential to future scientific research into ACTs. CF patients will benefit from evidence that their daily physiotherapy regimes are effective, and NHS costs will be reduced by more effective regimes.

    Lay summary of study results:
    The purpose of the study:
    People with cystic fibrosis (CF) are usually recommended to perform chest physiotherapy (also known as airway clearance techniques) as part of a daily routine. Traditionally the effect of these techniques, clinically and in research, have been assessed by how each patient feels during and after completing the technique, alongside changes in lung function (particularly FEV1), amount of sputum cleared and oxygen saturations. Although these tests have been used historically, there is now some debate about whether they are the best measure to actually show the effect of airway clearance. Recent technological developments have seen some new tests developed which may give a more detailed picture into the short-term effects of airway clearance techniques. In this study we compared the traditional measures of sputum cleared, FEV1 and oxygen saturations with these new tests. We felt that having a more detailed measure to assess the effect of an airway clearance technique, would be both helpful clinically to aid the selection of the correct technique for an individual, and for future research into what makes an effective airway clearance technique. This knowledge would then hopefully not only help adults with CF, but would be able to guide research into other disease groups who have sputum and need to complete airway clearance. As well as finding out which test gave the best clinical information for us, we were keen to know how people with CF felt about these new tests. Therefore, we asked participants to complete a questionnaire at the end of the study asking which outcome measure they preferred and why.

    What the study involved
    The study involved our volunteers, who were adults with CF, attending the Royal Brompton Hospital Research Facility (based in the Fulham Road Wing) for 2 visits for approximately 4 hours. This was a cross-over trial, meaning that on one visit they completed the outcome measure tests (as described below), then completed a session of airway clearance physiotherapy and then repeated the outcome measure tests again; on the other visit they completed a period of rest instead of physiotherapy. The reason a period of rest was included was to provide information on whether the tests would change without any physiotherapy. The study tests

    Participants were asked to complete the following tests during the study visit. They could rest in-between the tests if they wished to.
    • Lung function (also called spirometry) - These included FEV1 and FVC, using a hand held spirometer the same as they use in clinic and on the ward. The technique involves taking a deep breath and then blowing out through the machine as hard as you can for as long as you can. This was completed 3 times, which took up to 10 minutes.
    • The lung clearance index (LCI) - This is a technique which involves breathing quietly through a tube whilst wearing nose clips. The test measures harmless tracer gases which are breathed in and out and measured by a sensitive gas-detection system. The LCI is calculated based on how long it takes for the gas to be breathed out from the lungs, and it shows if there are areas within the lung that are working less efficiently than others, for example when areas of the lung are clogged with mucus. Participants performed this test 3 times, which took about one hour.
    • Impulse oscillation system (IOS) - The Impulse Oscillation system is a non-invasive technique where a person breathes normally through a mouthpiece whilst wearing a nose clip, into a machine which produces small pressure vibrations (oscillations). The machine measures these vibrations and any changes to them to give an idea of obstructions to the airways, for example any mucus clogging. Participants completed this test 3 times, which took a total of up to 15 minutes.

    Participants then completed a session of airway clearance (breathing exercises) or rest for 30 minutes. During this they completed
    • Oxygen saturation monitoring - Completed by wearing a probe on their finger throughout the session.
    • Sputum collection - Participants are given a specially weighed pot in which they were asked to spit out any sputum that they cleared during the 30-minute session. This pot was weighed at the end of the session and is discarded appropriately.
    • Electrical impedance tomography (EIT) - This technique involves wearing a belt around the chest which has electrodes attached to it. Undetectable alternating electrical currents are then applied to the electrodes, which the person cannot feel. The machine measures how easy or difficult it is for that current to travel through the lungs and any differences are calculated, giving a picture of the ventilation of the lung.

    After the rest or airway clearance session is completed the participants repeated the same measures they did before the session, these are
    o Lung function tests
    o The lung clearance index
    o Impulse oscillatory technique

    Participants also completed a questionnaire after each study visit, which asks their views on the on the tests completed during the visit and a questionnaire asking how clear their chest felt after the airway clearance/rest sessions.

    Results of the study

    We found that out of the five outcome tests we studied (FEV1, sputum weight, LCI, IOS and EIT) only sputum weight changed significantly after airway clearance compared to rest. This indicates to us that the other four measures (FEV1, LCI, IOS and EIT) are not suitable measures for the effect of a single session of airway clearance. However, while sputum weight did show a difference this is limited to those people who clear sputum and thus is not suitable for everyone. Therefore, we need to try to find a different measure for the effects of airway clearance.

    We also found from our self-reported questionnaire no participants reported that their breathing had changed after completing airway clearance. Most of the tests we usually use for assessing airway clearance are breathing tests…but if breathing does not change, then using tests that assess breathing may not be the most useful. Therefore, again we need to look for an alternative way of measuring the effect of airway clearance.

  • REC name

    London - Chelsea Research Ethics Committee

  • REC reference


  • Date of REC Opinion

    27 Jun 2016

  • REC opinion

    Favourable Opinion

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