Description of the condition
Asthma is a chronic inflammatory disorder of the lungs that can lead to structural and functional changes resulting from bronchial hyperresponsiveness and airflow obstruction (Allen 2012; Brightling 2012; Holgate 2009; Taylor 2008; Zhang 2010). Symptoms of asthma include recurrent episodes of wheeze, cough, breathlessness and chest tightness, together with episodes of marked worsening of symptoms known as exacerbations (Bateman 2008; Brightling 2012; Zhang 2010). The diagnosis of asthma is based on the individual's medical history, physical examination findings and lung function and laboratory test results (Sveum 2010).
Asthma is a serious public health problem and a major cause of disability and health resource utilisation among those affected (Bateman 2008; Eisner 2012; To 2012). Around 300 million individuals of all ages worldwide are affected by asthma (Bateman 2008; Bousquet 2010; Brightling 2012). Asthma is the most common chronic disease in childhood (Solé 2006). Increased morbidity, mortality and economic costs are associated with patients with severe or difficult to treat asthma, particularly in industrialised countries (Eisner 2012; Zhang 2010). In addition, psychological symptoms may interfere with the severity of respiratory symptoms and may influence patients’ quality of life (Juniper 2004; Rimington 2001). Such consequences affect not only the patient but the whole family universe (Nogueira 2009), especially when it comes to children.
Asthma is sometimes associated with symptomatic hyperventilation, which decreases carbon dioxide (CO2) levels, causing hypocapnia (Bruton 2005a; Laffey 2002; Thomas 2001). Hypocapnia resulting from hyperventilation may perpetuate the bronchospasm, culminating in a cycle of progressive hypocapnia and increasing bronchospasm (Laffey 2002). Thus, hypocapnia may contribute to increased airway resistance in patients with asthma (Laffey 2002; van den Elshout 1991). This fact has led to increasing interest in strategies that can be used to reduce hyperventilation.
Description of the intervention
The main objective of asthma treatment is to achieve and maintain its clinical control (GINA 2012). Although no cure for asthma is known, its symptoms are controllable in most patients (Taylor 2008). Asthma treatment can be pharmacological or non-pharmacological or a combination of these approaches; it includes strategies of symptom control (information on environmental triggers and asthma education) to reduce symptoms and improve quality of life related to health (Burgess 2011; Rimington 2001; Welsh 2011).
Pharmacological treatment of asthma consists of maintaining control of the disease with the least medication, thereby minimising risks of adverse effects (Sveum 2010).
Non-pharmacological treatments have been used widely by researchers and professionals in the search for complementary therapies for the treatment of asthma; their use is reported in approximately 42% of patients in some populations (Blanc 2001). Some patients are interested in non-pharmacological therapies because they may feel or hope that they will lead to improvement in overall health (Bishop 2008), and because they are keen to try to reduce the need for pharmacological treatment (Brien 2011). Complementary medicine includes breathing exercises, homeopathy, acupuncture, aromatherapy, reflexology, massage, inspiratory muscle training and the Alexander technique (Blanc 2001; Bruton 2005b; Cooper 2003; Dennis 2012; Grammatopoulou 2011; Holloway 2007; Lima 2008; McCarney 2003; McHugh 2003).
Breathing exercises have been used routinely by physiotherapists and other professionals to control the hyperventilation symptoms of asthma (Bruton 2005b) and can be provided in the form of the Papworth method, the Buteyko breathing technique, yoga or any similar intervention that manipulates the breathing pattern (Ram 2003). Even though breathing exercises are commonly used, there is not a consensus regarding the effectiveness of breathing exercises. It was previously reported that groups with the same baseline characteristics may show different responses to different breathing exercise techniques (Prem 2013). Also, the duration of the intervention may interfere with the response to treatment, as was suggested previously (Grammatopoulou 2011). A previous systematic review on breathing exercises for asthma included studies performed in participants with mild to severe asthma (Ernst 2000). However, meta-analysis was not provided to assess the impact of breathing exercises at different levels of asthma severity.
How the intervention might work
Breathing exercise techniques focus on the use of an appropriate breathing pattern to reduce hyperventilation and hyperinflation, thereby increasing CO2 levels, which may reduce bronchospasm, normalise the breathing pattern and reduce breathlessness (Bruton 2005b; Burgess 2011). Such techniques may also be used to help reduce anxiety associated with asthma symptoms (Singh 1990). Therefore, breathing exercises in patients with asthma may provide psychological benefits by increasing patients' sense of control over their condition (Ram 2003).
Why it is important to do this review
The worldwide high prevalence of asthma became a public health problem because of the high healthcare costs resulting from hospitalisation and medication (Giavina-Bianchi 2010). Asthma promotes changes in the whole family context, not only because of the costs associated with health care, but also because of the impact of this condition on daily living, including patients’ quality of life (Ferreira 2010).
Asthma control is promoted by the correct use of medication and may be associated with other therapies, such as breathing exercises. Such techniques have been widely used as adjunct therapy in the treatment of asthmatic patients, generating considerable interest among researchers to develop studies that aim to provide evidence of this intervention. Recently, we published a Cochrane systematic review regarding the use of breathing exercises in adults with asthma (Freitas 2013). This review included studies that differed significantly in terms of intervention characteristics, such as types of breathing exercises, numbers of participants, numbers and duration of sessions, reported outcomes and statistical presentation of data. Such differences limited meta-analysis and attainment of conclusive results. On the other hand, this review indicated that breathing exercises are a safe and well-tolerated intervention for people with asthma. Similarly, no conclusive evidence was provided in two previous systematic reviews (Ernst 2000; Ram 2003), even though outcomes reported from individual trials showed that breathing exercises may have a role in the treatment and management of asthma.
It is important to synthesise the evidence obtained on such techniques, taking into account their effects in the paediatric population. To our knowledge, no systematic review on this topic has been published previously. Thus, within this review, we aim to summarise and assess evidence from randomised controlled trials regarding the effects of breathing exercises in children with asthma.