Respiratory medicine

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chapter 41 Respiratory medicine



It is estimated that worldwide as many as 300 million people of all ages have currently diagnosed asthma. The prevalence of asthma in Australia is quite high, with one in six children (14–16%) and one in nine adults (10–12%) having the disease.2 There is variation between countries in the incidence of asthma (this is detailed in the document Global burden of asthma (see Resources list at the end of this chapter)).

The condition we call asthma involves a number of pathological processes including inflammation, smooth muscle spasm and increased airways secretions. In essence it is a chronic inflammatory disorder affecting the airways. Many types of cells play a role in this inflammatory process, including mast cells, eosinophils, T-lymphocytes, macrophages, neutrophils and epithelial cells. Individuals who experience asthma generally have a genetic susceptibility that can also be affected by lifestyle and environmental factors. Airway inflammation causes recurrent episodes of asthma associated with the symptoms of wheezing, shortness of breath, chest tightness, and also coughing, most commonly at night or in the early morning or in response to exercise. These episodes of wheezing and dyspnoea brought on by widespread airflow obstruction will reverse spontaneously or with treatment.2 In those disposed to airway hypersensitivity, the inflammation is usually triggered by environmental factors such as allergens, irritants and temperature change. Psychological and emotional factors can also trigger or aggravate episodes of asthma.



The ‘hygiene hypothesis’4 is a theory, still being debated,5 that links an increased risk of atopic disease with reduced microbial exposure from a variety of sources during childhood. Epidemiological studies are providing increasingly strong evidence that protection from atopic disorders including asthma is afforded by early-life exposure to environmental microbes. For example, children who are raised on farms, who drink unpasteurised milk, have more older siblings or attend day care at an earlier age are protected to some extent against asthma. This may explain to some extent the ‘asthma epidemic that has been occurring, especially in developed nations, over the past several decades’.6

If the ‘hygiene hypothesis’ is correct, letting children ‘get down and dirty’ may become a preventive activity!

Respiratory hygiene and minimising spread of infection is important in preventing exacerbations. Ensure routine immunisation against Haemophilus influenzae, seasonal influenza and pertussis (whooping cough).


Many self-help strategies or home remedies are suggested but robust evidence of their efficacy is often lacking. Self-help strategies or home remedies that have been subjected to scrutiny and are listed in the medical literature are described below.

Fish oil

Many people with asthma who change their diets to include more fish oil do not improve their asthma,11 but other evidence has suggested that others do. There has been some work published on taking fish oil supplements (rather than just increasing fish in the diet). In one study,12 some benefit was shown in people with predominately exercise-induced bronchospasm (EIB) but the authors have given the guarded advice that ‘fish oil supplementation may represent a potentially beneficial non-pharmacological intervention in asthmatic patients with EIB’.

Breathing exercises

The way in which ‘breathing exercise’ or ‘re-training’ is understood varies depending on the form of the therapy, the therapist providing the therapy and the cultural background of the person having the therapy. Some of the earlier studies of breathing exercises were small or had methodological flaws, but more recent studies demonstrate a trend for improvement.15 Evidence on breathing exercises, including yoga-based breathing exercises16, in asthma suggests that they can provide objective and subjective benefit and can be useful in reducing the need for reliever and preventer use.17 The Buteyko method is also widely used in asthma. Evidence suggests that it provides subjective benefit, although results indicating whether it also provides objective benefit have been inconsistent. It is best to learn breathing exercises from health professionals trained in their use.

Complementary therapies


The evidence is not clear and consistent enough to make firm recommendations about the value of acupuncture in asthma.21 It may be that some forms of acupuncture are more beneficial than others, or that acupuncture is beneficial for some variants of asthma but not others.



Chronic obstructive pulmonary disease (COPD) is a major cause of disability, hospital admission and premature death. It is commonly associated with other diseases including heart disease, lung cancer, stroke, pneumonia and depression.26 In a community-based survey that included lung function testing, doctor-diagnosed chronic bronchitis or emphysema was reported by 4.3% of the population. When clinical diagnosis is combined with complex lung function testing and an FEV1/FVC of less than 75%, around 12% of the population have some evidence of emphysema.27 This figure will be considerably higher in countries where anti-smoking legislation and campaigns are less prominent.

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