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CPD for GPs - a commitment to structured skills enhancement and personal or professional competence.

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Lorimer Moseley's TED talk on contemporary pain neuroscience theory

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Lorimer Moseley's TED talk on contemporary pain neuroscience theory

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TEDxAdelaide - Lorimer Moseley - Why Things Hurt

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Exercise induced asthma/bronchoconstriction and vocal cord dysfunction

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Julie Depiazzi , Mark L. Everard

Abstract

Key points

Abstract

Breathlessness: accurate assessment and diagnosis is essential in order to provide correct advice and assistance http://ow.ly/4nrW8z

Introduction

Perceived excessive breathlessness during exertion or exercise-induced dyspnoea (EID) is reported to be the commonest symptom limiting performance and/or enjoyment when participating in sporting activity among children, adolescents and young adults [ 1, 2]. Indeed for some the sensation of excessive breathlessness is given as a reason for not participating in physical activity. This is observed across the spectrum from occasional recreational participation to elite athletes. Clarifying the cause of the perceived symptoms requires careful assessment with a wide range of factors potentially contributing to the reported symptoms.

Asthma and exercise-induced bronchoconstriction (EIB) are relatively common causes of EID. However, a presumptive diagnosis of asthma is often made based on a subjective history without objective confirmation and as a result over diagnosis is common. In part this is attributable to a lack of awareness of possible alternative diagnoses or comorbidities that may be responsible for the reported breathlessness. This has led to many individuals receiving inappropriately prescribed "asthma" medications for EID caused by other conditions, or receiving excessively high doses as comorbidities are not recognised. Failure to clearly identify the cause of the individual's symptoms also deprives them of appropriate management resulting in ongoing impairment of their quality of life (QoL) and unnecessary healthcare utilisation.

This article considers the range of problems that may masquerade as, or coexist with, exercise-induced asthma in causing dyspnoea. While serious cardiovascular, pulmonary or upper airways pathology can cause EID, it is much more likely the cause is "benign" or functional. From studies of symptomatic subjects it would appear that reaching their physiological limit or experiencing a form of "dysfunctional breathing" are the commonest causes [ 1, 2]. The following sections aim to help clinicians recognise when referral to a respiratory physiotherapist or speech pathologist is useful, and highlights the need for awareness of rare but important structural or pathological causes.

Conditions causing EID

Individuals reporting EID are frequently looked after by nonspecialists in the community, although many are referred on to respiratory clinics with "difficult asthma" when they fail to respond to standard therapy. Others present to otolaryngologists when an upper airways cause is suspected or to psychologists with "hyperventilation syndrome" (HVS).

Figure 1 outlines the range of conditions that may present with EID and provides a possible framework for clinicians when presented with a complaint of perceived excessive breathlessness during physical activity. In studies exploring the causes of EID in young people, those with asthma are usually in the minority [ 1- 5]. The most common diagnosis appears to be that the breathlessness is appropriate and that individuals are reaching their physiological limit. This can apply to those attempting to compete at the highest levels as well as those who are "deconditioned" due to lack of adequate training, obesity or indeed recent severe illness. Also common are the conditions grouped under the umbrella term dysfunctional breathing, which can be due to thoracic or extrathoracic problems and include both structural and functional causes. This area is perhaps the least well understood and researched. Patients with chronic pulmonary disease may manifest any of these as a comorbidity and this needs to be borne in mind while accepting that the disease alone can be responsible for reported EID. The prevalence of the various causes of EID in the community has not been determined.

Exercise-induced asthma and EIB

The impact of exercise on asthmatic subjects is well recognised, with bronchoconstriction occurring in asthmatic subjects following 5-8 min of intense exercise and nonselective β-agonists preventing or greatly lessening the resultant fall in forced expiratory volume in 1 s (FEV ₁) [ 6]. Given this "typical" pattern, the cause of the EIB is unlikely to be bronchoconstriction when individuals report that symptoms commence shortly after initiating vigorous activity. It is recognised that some individuals experience EIB associated with chest tightness, cough and wheeze without other interval symptoms of asthma and hence many consider that it can exist independent of "classic" asthma [ 7, 8].

EIB appears to be common in athletes [ 6, 8], more so in those that: are endurance athletes, have allergic rhinitis, are female, or who exercise in cold weather or in chemical environments such as swimming pools [ 7- 10].

The vast majority of individuals with exercise-induced asthma/EIB can be managed very effectively with inhaled corticosteroids and pre-exercise β-agonists. Failure to control symptoms suggests nonadherence or an alternative diagnosis as the cause of symptoms in all but a very small minority.

Deconditioning and the physiological limit

The term deconditioning is used interchangeably to describe different physical presentations. Frequently, deconditioning is used to refer to a lower than expected physiological limit to exercise. True physiological deconditioning occurs after prolonged illness, bed rest or a sedentary lifestyle where associated cardiovascular and neuromuscular physiological changes lead to a reduction in maximal oxygen uptake and reduced cardiac output with exercise [ 11, 12]. This is different to the individual with a complaint of breathlessness and fatigue with exercise, but who is still able to reach their predicted physiological limit without ventilatory or cardiac limitation ( figure 1).

Individuals presenting with excessive breathlessness may be truly deconditioned, as in the case of a post-critical illness patient, or have a perception that their breathlessness with exercise is abnormal despite normal physiological responses to skeletal and respiratory effort during cardiopulmonary exercise testing (CPET) [ 1, 2]. Perceived breathlessness for any given task or activity can vary widely between individuals with no association found between the level of perception of dyspnoea and the level of physical activity [ 13]. The athlete with EID may report excessive breathlessness due to a hypersensitivity to their normal physiological response. Likewise, the "unfit" person may have a normal CPET but be "unconditioned" rather than "deconditioned" in their perceived response to exercise.

Reports of deconditioning in the literature as a cause of EID are difficult to ascertain with variability in its definition and meaning. However, it should not be excluded as a significant contributor to EID in otherwise healthy young people. CPET studies on healthy adolescents and adults who report EID have reported low fitness levels or deconditioning caused EID in 23-67% of cases, exceeding any other contributing diagnosis to EID [ 1, 2]. It is also important to recognise that not all individuals with obesity are deconditioned. Young people who are overweight may display expiratory flow limitation at sub-maximal exercise [ 14]. In some, compensatory breathing strategies can limit breathlessness, but for others there is an increased perception of dyspnoea [ 14, 15]. Although objective investigation into the causes of EID is recommended [ 16] it would appear that few healthy young adults seeking medical advice for breathlessness undergo diagnostic testing [ 7, 9].

Dysfunctional breathing

Dysfunctional breathing can be considered an umbrella term that describes: "An alteration in the normal biomechanical patterns of breathing that result in intermittent or chronic symptoms which may be respiratory and/or nonrespiratory " [ 17]. Patients with dysfunctional breathing present with a variety of respiratory and nonrespiratory symptoms, including EID, shortness of breath at rest, "wheeze", stridor, throat tightness, sighing, chest pain, throat clearing, "air hunger" (a sense of being unable to get a complete breath in even after a maximal inspiratory manoeuvre), tingling, dizziness and general fatigue [ 17, 18]. Frequently a number of symptoms coexist, although one may predominate.

The biomechanical patterns of breathing typified by dysfunctional breathing may be altered by structural or functional factors ( figure 2). An awareness of structural causes such as repaired diaphragmatic hernia and abnormalities of the vocal cords is important. Recognition of exercise-induced laryngomalacia with the advent of continuous laryngeal examination to characterise the cause of upper obstruction occurring during intense exercise, represents a significant advance in this field [ 19, 20]. This structural abnormality is important in that surgery can be undertaken and is increasingly being carried out for competitive sports men and women [ 19].

This review will focus on the more common functional dysfunctional breathing, which appears to represent habituated alterations in breathing patterns, and can be further classified as thoracic or extrathoracic. Thoracic dysfunctional breathing presents as alterations in the pattern of respiratory muscle activity (pattern disordered breathing (PDB)), which may or may not be associated with hyperventilation, while extrathoracic dysfunctional breathing describes conditions affecting the upper airway, such as paradoxical vocal fold motion disorder (pVFMD), in addition to PDB.

Unusual pathogenic causes

While this review has focused on the more common and benign causes of EID, it is important to consider the unusual and rare in the differential diagnosis of unexplained breathlessness not responsive to asthma medication. Intrapulmonary or intracardiac shunting due to conditions such as the hepatopulmonary syndrome, significant arteriovenous malformation and some forms of intracardiac shunting that increase with exercise may result in rapid onset of symptoms with desaturation. Exercise-induced arterial hypoxaemia is reported in some well-trained athletes in the absence of identified shunting, although the mechanism is not fully understood. Exercise-provoked cardiac arrhythmias such as supraventricular tachycardia may be difficult to identify from the history unless actively sought. Exercise-induced anaphylaxis is a potentially fatal rare cause that has been recently reviewed, and case studies have been reported of swimming induced pulmonary oedema and pulmonary embolus in athletes [ 7, 34]. Similarly increased fatigue and reduced exercise tolerance are common among those developing anaemia and chronic thromboembolic disease, and both are easily overlooked by the respiratory physician. Thus, being conscious of rare but very important pathologies that can impact on exercise tolerance is very important.

A clinical approach to the patient with EID

Inaccurate assessment of the individual with EID may result in inappropriate therapy and failure to provide symptom relief. As with any presenting complaint, a careful history is essential. Examination can be helpful and appropriate use of investigations may be necessary to provide a definitive diagnosis. While investigations such as CPET and continuous laryngoscopy during exercise (CLE) may be relatively expensive to undertake, they may save the healthcare provider money by preventing unnecessary interventions and follow-up, while ensuring the best possible outcome for the individual. The following will concentrate on nonasthmatic causes of EID.

Treatment pathways for functional breathing abnormalities

An increasing number of literature reviews and randomised controlled trials demonstrate the emergence of recognition that not all breathlessness in otherwise well individuals is asthma [ 1, 2, 5, 16- 18, 23, 25, 30, 40]. When an individual does not respond to asthma medication, or does not respond as well as expected, comorbidities such as dysfunctional breathing, simple deconditioning or sensitivity to a normal physiological response to exercise need to be considered.

There appear to be common factors contributing to the onset of extrathoracic and thoracic "functional" dysfunctional breathing. Both are frequently found in the self-driven person and athlete, and both appear to be helped with breathing retraining. Classification can assist treatment with referral to a speech pathologist for management of extrathoracic dysfunctional breathing and to a respiratory physiotherapist for thoracic dysfunctional breathing. Those with a combination of extrathoracic dysfunctional breathing and PDB may best be managed by both professions and could be considered to be a more severe form of the same basic condition. As with management of many conditions it is important that the therapist to whom the patient is referred has an interest in the condition.

Recommendations for the management of thoracic dysfunctional breathing are found in recent guidelines for physiotherapists [ 41]. Published research protocols generally follow treatment principles that focus on education about the condition, reassurance, abdominal breathing retraining, breathing rate and depth control, breathing retraining in progressively taxing postures such as walking, recognition of triggers, and control of symptoms during an episode and manual therapy [ 18, 24, 25]. Studies have demonstrated a reduction in respiratory symptoms and hospital visits and an improvement in health-related QoL and athletic performance over relatively short periods of two to eight clinical visits with a physiotherapist [ 25, 33, 42- 44]. Furthermore, benefits have been maintained in some groups from 6 months to 5 years [ 33, 42]. Treatment practices often add manual therapy to address musculoskeletal dysfunction; however, adding manual therapy in addition to breathing retraining techniques has not yet been proven to add further benefit to the relief of symptoms [ 25].

Treatment for deconditioning should include individualised exercise prescription and management of associated musculoskeletal dysfunction; however, reassurance and education is also required. In a study intended to provide breathing retraining, a large number of children with EID, who performed a normal CPET, went on to decline intervention, leading the authors to suggest that in children reassurance in itself from conclusive objective testing may be a beneficial treatment [ 2].

While some studies have suggested children with EID report similar activity levels to their healthy peers [ 4], of concern is the early termination of activity in others [ 3]. A cycle of perceived excessive EID, regardless of cause, will perhaps lead to a cycle of activity avoidance and deconditioning. In the modern world of increasing sedentary behaviour and a health-related obesity crisis, failing to identify and treat benign EID in children and adolescents may have long lasting cost and health impacts.

Clinics and multidisciplinary teams established to manage the complex patient with breathlessness are becoming more common. A recent report from the UK's first paediatric respiratory physiotherapist run dysfunctional breathing clinic indicated dramatic improvements in QoL that were sustained when subjects were re-evaluated 6 months after the last of their four sessions at the clinic [ 45]. Another recent report describes the experience of a specialised "airways clinic" in the UK, in which patients referred with complex breathlessness are seen by a physician and have access to experienced speech pathologists and physiotherapists attached to their team. This clinic reports a significant number of their patients with severe asthma or chronic lung disease to also have PDB and/or vocal cord dysfunction. Despite a protracted history of symptoms in most, patients reported clinical improvement with multidisciplinary team intervention addressing their dysfunctional breathing [ 21].

Conclusion

EID is a common symptom reported in young people and adults and can affect QoL and engagement in physical activity. Bothersome EID may be a symptom of serious cardiovascular or pulmonary disease, or of a benign cause. Differential diagnosis of EID is important to guide clinical management that maximises treatment effect and minimises unnecessary medication prescription. The clinician should "seek to do no harm", harm in the context of EID could be failure to diagnose the cause accurately and the administration of unnecessary and potentially harmful drugs, while failing to deal with the underlying problem and hence perpetuating a condition that is impacting negatively on the patient's QoL.

Careful clinical evaluation based on a clear conceptual map of potential causes linked to appropriate testing should be the standard. Lung function testing with appropriate use of challenge testing, CPET testing and/or CLE should form part of an integrated approach to the athlete (at whatever level) who is reporting limitation of exercise due to their breathing.

Thoracic dysfunctional breathing appears, based on the limited data available, to affect up to 10% of the population and 30% of the asthmatic population, yet few individuals are being referred to respiratory physiotherapists. This reflects a lack of awareness of the nature, prevalence and impact of the condition among many clinicians. Consequently funding bodies do not appear to recognise it as an important cause of morbidity worthy of funding, thus perpetuating this situation. Clarity in our approach to dysfunctional breathing is vital if funding is to be made available for high quality studies designed to identify the prevalence and the potential healthcare cost saving and improvements in QoL that would follow from accurate assessment and intervention.

View Abstract

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Dysfunctional breathing and reaching one's physiological limit as causes of exercise-induced dyspnoea

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Key points This review provides an overview of the spectrum of conditions that can present as exercise-­induced breathlessness experienced by young subjects participating in sport and aims to promote understanding of the need for accurate assessment of an individual's symptoms. We will highlight the high incidence of nonasthmatic causes, which simply require reassurance or simple interventions from respiratory physiotherapists or speech pathologists.

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