This is an early version of an invited paper I produced for Drug and Therapeutics Bulletin (2015 53:126-9 doi:10.1136/dtb.2015.11.0361). The published version is very different!
Introduction Asthma is still amongst the commonest long-term conditions, it is incurable, and outcomes have stopped improving, despite clinicians’ best efforts using pharmacological approaches (Martinez & Vercelli, 2013). There is considerable public interest in the use of non-pharmacological approaches in the treatment of asthma, and particularly in the use of breathing exercises (Bruton & Thomas 2100). Surveys suggest many people with asthma use them, often without the knowledge of their clinical team. However, the phrase ‘breathing exercises’ is vague and encompasses many different techniques, only some of which have a convincing evidence base. The techniques with the strongest evidence base are those that aim to ‘retrain’ breathing pattern to encourage patients to breathe through the nose, to breathe more slowly and regularly, and to reduce upper thoracic movement. The role of breathing exercises within the management of asthma has been controversial, partly because early proponents made exaggerated, implausible claims of effectiveness. Recent evidence suggests that breathing retraining programmes are effective in improving patient-reported outcomes such as symptoms, quality of life and psychological impact; and may reduce the use of rescue bronchodilator medication. This has resulted in endorsement of breathing retraining as an add-on treatment in asthma in systematic reviews and guidelines. The guidance is only applicable to adults with asthma, as there is little paediatric evidence beyond anecdote. Despite the observed clinical benefits in adults with asthma, there is currently no convincing evidence that airways physiology, hyper-responsiveness or inflammation is affected by breathing exercises. The mechanism behind breathing retraining therefore remains uncertain, with both psychological and physiological theories proposed.
Background Breathing exercises for asthma can be broadly divided into four groups: exercises aimed at manipulating the pattern of breathing (breathing retraining), exercises aimed at increasing the strength and/or endurance of the respiratory muscles (inspiratory muscle training); exercises aimed at whole body conditioning (aerobic training); and exercises aimed at increasing the flexibility of the thoracic cage and improving posture (musculoskeletal training). Some individual techniques may address more than one of these group aims. Each group of exercises contains a range of approaches and rationales. In addition there are specific technologies/ equipment that can be used to provide biofeedback during exercises. The main focus in this article will be on techniques with the most convincing evidence base, which are the ones used in breathing retraining.
Breathing retraining exercises aimed at manipulating the pattern of breathing include: physiotherapy techniques (such as Papworth), yoga breathing techniques, Buteyko breathing techniques, and improving breath control through singing or musical instruments. Some of the issues with all breathing retraining trials are the lack of detail in the description of the techniques used, and the lack of uniformity in use of language (Bruton et al, 2011). In RCTs reported by Thomas et al (2003, 2009), and Holloway & West (2007) the phrase ‘diaphragmatic breathing’ is used. In reality, in the absence of phrenic nerve malfunction, all breathing patterns involve diaphragmatic activity, so this phrase is not an accurate description, but has become synonymous with breathing with more movement from the abdomen than upper chest. One problem with the term diaphragmatic breathing is that it can be interpreted to mean ‘slow and deep’ or ‘normal rate and tidal volume’ breathing, depending on when and where you were trained (Bruton et al, 2011). Nevertheless, most breathing retraining packages include greater emphasis on abdominal and lower thoracic excursion during inspiration, with reduced emphasis on upper thoracic excursion. But this is only one element of the package. Breathing retraining is a complex intervention frequently comprising multiple components (both respiratory and non-respiratory). Respiratory components involve some form of breathing pattern manipulation, while non-respiratory components may include, for example, varying amounts of nutritional advice, medication usage advice, and psychological support to address the associated anxiety which can accompany asthma (Thomas et al, 2011).
Main body The evidence for breathing exercises other than breathing retraining is either weak or non-existent. Although musculoskeletal training to increase flexibility and improve posture in asthma has some strong clinical proponents, there is insufficient trial evidence to support their use. Specific named techniques such as the Alexander Technique (which is a form of therapy involving postural realignment and relaxation) have no trial evidence in asthma found to be suitable for inclusion in a recent Cochrane review(Dennis & Cates, 2012). Manual therapy techniques aimed at increasing the movement of the ribcage and spine to improve lung function also have insufficient evidence to support or refute their use for patients with asthma (Hondras et al, 2005). There has been recent interest in music therapy for asthma (both listening and playing), and there is some logic to the use of breath control techniques associated with singing, or playing a wind instrument, but there is again insufficient evidence to support its use (Sliwka et al, 2014). None of these breathing exercises/ techniques is recommended within current guidelines for asthma. There is, however, some evidence that inspiratory muscle training may have an effect. A recent Cochrane review included five studies involving a total of 113 adults (Silva et al 2013), although three of these were from a single research group. Inspiratory muscle strength generally increased significantly (as you would expect after resistance training for any skeletal muscle), but no clinical benefit (such as change in quality of life or breathlessness) was observed. The review concluded that there was currently no evidence to support or refute the use of inspiratory muscle training in asthma.
Physical training also has some positive evidence. One Cochrane review of physical training for asthma (Ram et al, 2005 ), based primarily on paediatric studies, concluded that while physical training improves cardiopulmonary fitness, it has no effect on resting lung function or number of days with wheeze. A systematic review (Pakhale et al, 2013) included 23 studies (total number of participants not documented). Although the authors stated that physical training might reduce airway inflammation in asthma, the review was essentially inconclusive. A more recent Cochrane review in 2013 concluded physical training showed significant improvement in maximum oxygen uptake, but no effects were observed in other measures of pulmonary function (Carson et al, 2013). However, the training was well tolerated and although physical training may have no specific asthma-related effects, the general benefits of physical training mean that some authors recommend its use in asthma (Bott et al, 2009), even though they are not specific about dose/ duration/type of training to be used. The Cochrane review concluded: “People with stable asthma should be encouraged to participate in regular exercise training, without fear of symptom exacerbation” (Carson et al, 2013).
Breathing retraining The breathing retraining techniques most frequently investigated in research trials have been physiotherapist administered breathing exercises (Papworth and similar) (Holloway & West 2007; Laurino et al, 2012; Thomas et al, 2003, 2009) the Butekyo breathing method (Cooper et al, 2003; Cowie et al, 2008; Opat et al, 2000) and yogic breathing (Manocha et al, 2002; Singh et al, 2012; Singh et al, 1990). Although each has a different philosophical standpoint and rationale, there are considerable overlaps within their delivery methods. Of the three approaches, physiotherapy and Buteyko have the higher level of evidence and are now mentioned in BTS/SIGN guidelines for asthma management (British guideline on the management of asthma, 2014). Although some practitioners are applying these techniques clinically to children and teenagers, the only robust current research trial evidence applies to adults, with a recent Cochrane search for evidence in other age groups finding zero papers for inclusion in their review (Barker et al, 2013).
The general aims of breathing retraining are to ‘normalise’ breathing pattern, usually by adopting a slower respiratory rate with longer expiration and reduction in overall ventilation. Use of abdominal rather than the upper-chest and accessory muscles of ventilation in resting breathing, and nasal rather than mouth breathing, are also frequently stressed. The rationale for this retraining is based on the assumption that some people with asthma have abnormal or dysfunctional breathing patterns, either continuously or intermittently in association with bronchospasm. The evidence for this assumption is fairly weak, as few reliable studies have compared breathing patterns in people with asthma to healthy subjects, particularly at times of bronchoconstriction. People with asthma (even mild well controlled asthma) have been found on average to have a lower arterial and end-tidal carbon dioxide tension than matched non-asthmatic subjects, indicating a tendency to over-breathe (Osborne et al, 2000). There is also indirect evidence of dysfunctional breathing from UK surveys reporting 1/3 of women and 1/5 of men treated for asthma in general practice to have symptoms suggestive of hyperventilation (Thomas et al, 2001) and from Spain (Martinez-Moragon et al, 2005)reporting that 1/3 of asthma patients in a Spanish pulmonology clinic had such symptoms. Approximately 1/5 of patients attending UK difficult asthma clinics were found after detailed assessment to have functional breathing disorders (including dysfunctional breathing and vocal cord dysfunction) as a major factor in their illness (Heaney & Robinson, 2005).
Breathing retraining for asthma should be considered as a complex multicomponent behavioural change intervention involving both instructional and practice phases. In clinical practice, the instruction phase of the intervention is conventionally delivered individually via face-to-face methods between a patient and a therapist. Although some studies have used small group delivery, no direct comparisons have yet been trialled for group versus one-to-one delivery. Some trials have used alternative ‘distance’ delivery methods such as in an Australian study investigating the effects of two breathing training programmes delivered as a videotaped instruction programme (Slader et al, 2006). Both programmes were associated with improved health status and major reductions in bronchodilator use from baseline values. They have subsequently been made available as Internet downloads and used in Australia to improve asthma control in routine practice. The minimum length and number of instruction sessions required to achieve improvement is not known, and in clinical practice tends to be individualised according to the needs / learning speed of the patient. In our experience with physiotherapy breathing retraining, 3-4 instruction sessions spread over a period of about 6 weeks are effective. Patients are encouraged to put the various techniques into practice on a daily basis and to try to incorporate them into daily routines until they become ‘second nature’ and embedded into daily life. The ideal number and duration of practice sessions is also unknown, and as with the instruction sessions, is likely to vary between individuals.
Breathing retraining generally involves a ‘package’ of components. The Papworth (physiotherapy), Yoga, and Buteyko packages all have some core similarities, with breathing pattern modification being the primary component. Other common elements are advice on route of breathing, use of breath holding, relaxation and home exercises. The more variable elements across the packages are nutritional advice, medication usage advice, asthma education, aerobic exercise prescription, and use of biofeedback devices (such as use of capnometry, breathing rate, heart rate variability).
Evidence for breathing retraining in asthma One systematic review of breathing exercises in the treatment of asthma performed for the US Agency for Healthcare Research and Quality found 22 studies (O’Connor et al, 2012). Although these were heterogeneous in terms of methodology, intervention and quality, the review found that hyperventilation reduction techniques achieved a medium to large reduction in symptoms and reduction in medication use (1.5-2.5 puffs of Beta2 agonist per day), although with no improvement in pulmonary function. Generally, improvements were seen in patient reported outcome measures, particularly quality of life, rescue medication requirement and symptoms, with lesser or absent improvements in physiological disease parameters. The review concluded that ‘Behavioral approaches that include hyperventilation reduction techniques can improve asthma symptoms or reduce reliever medication use over 6 to 12 months in adults with poorly controlled asthma, and have no known harmful effects.’ An updated Cochrane review in 2013 of ‘Breathing exercises for adults with asthma’ (Freitas et al, 2013) with more restrictive criteria considered 13 studies involving 906 participants. Again, considerable heterogeneity was found, but six of seven studies reporting symptom control showed significant improvements with breathing exercises. All eight studies that assessed quality of life reported an improvement in this outcome. Effects on lung function were more variable, with no difference reported in five of the eleven studies, while the other six showed a significant difference favouring breathing exercises. Meta-analysis was possible only for symptoms and quality of life, and showed a significant difference favouring breathing exercises for both parameters. Recent guidelines now incorporate recommendations that breathing retraining exercises should be considered in adult asthma, with the 2015 GINA iteration stating that ‘Breathing exercises may be a useful supplement to asthma pharmacotherapy’ (Grade B). The non-pharmacological management section of the BTS-SIGN UK Asthma Guideline (2014) gives grade A recommendation to the statement ‘Breathing exercise programmes (including physiotherapist-taught methods) can be offered to people with asthma as an adjuvant to pharmacological treatment to improve quality of life and to reduce symptoms’.
Targeting – who benefits from breathing retraining? Asthma encompasses a variety of phenotypes, and different therapeutic approaches are effective in different patients (Anderson, 2008). At present, data from published trials suggest that those who would benefit most from breathing retraining are those with impaired quality of life (when assessed with a validated questionnaire such as the AQLQ) despite standard medication. Although intuitively one might think those with symptoms of hyperventilation would be more likely to benefit, in the largest trial to date no significant difference in response to training from those with higher hyperventilation symptom scores (evaluated using the Nijmegen questionnaire) or lower baseline carbon dioxide tension; similarly, anxiety and depression did not predict the response to treatment (Thomas et al, 2009).
Breathing retraining requires considerable commitment from the individual patient in terms of time and effort. It suits those who are happy to be involved with self-management but is unlikely to be effective in patients who prefer a ‘quick fix’, or who lack sufficient motivation to practice the techniques regularly. A problem for many clinicians and patients is accessing therapists who can provide this training, which can be problematic for many respiratory specialists, and even more so for community-based generalists. The cost-effectiveness of increasing access to respiratory physiotherapists or other suitable professionals has not been assessed. Currently many patients who are interested in this type of treatment can only access it by paying unregulated therapists or by self-help books, internet pages or You Tube films of unknown efficacy. We are currently investigating the clinical and cost-effectiveness of an interactive ‘digital’ audio-visual breathing training programme (which can be delivered by internet or DVD) compared to face-to-face programmes and usual care, in the BREATHE study (Bruton et al, 2013). Potentially, this could allow a method of allowing large numbers of people to access the treatment in a convenient and inexpensive way.
Conclusion Asthma is a complex, multi-faceted condition, and control is sub-optimal for most patients. There is now sufficient evidence to recommend breathing retraining as an adjunctive therapy for the management of asthma, provided it is delivered responsibly within the context of optimal medical care. It is unlikely that breathing retraining will affect the pathophysiology of asthma, although may improve symptoms, increase quality of life, and may reduce rescue bronchodilator use. For patients who are not achieving adequate control despite apparently adequate pharmacological treatment, informing them of the possibility of breathing retraining and referring them to an appropriate source of instruction would be in agreement with current evidence and guidelines. Access to trained therapists is an on-going issue, but future research may allow greater access to effective programmes delivered in other ways.
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