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).

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’.

Vitamin C, vitamin E and beta-carotenes

There is a great deal of research under way into whether specific dietary supplementation is of benefit in asthma. Consensus on the importance of eating enough fresh fruit is yet to emerge, but one review found that:

Longitudinal data support the hypothesis that fresh fruit consumption has a beneficial effect on the lung. Among children, consumption of fresh fruit, particularly fruit high in Vitamin C, has been related to a lower prevalence of asthma symptoms and higher lung function.¹³

The message is therefore that a healthy diet is far more likely to be beneficial in asthma than supplements, particularly in the presence of a poor diet.¹³

Tartrazine exclusion

Tartrazine is one of the most commonly used food and medication additives or colourants. The evidence that tartrazine makes asthma worse, or that avoiding it makes asthma patients better, is questionable.¹⁴

Pharmacological

The cornerstone of asthma management is the use of inhaled corticosteroids. The greatest challenge is in deciding when they are required and in what dose. The recommendation of the National Asthma Council Australia is summarised in Figure 41.3.^2a

FIGURE 41.3 Management of mild, moderate and severe persistent asthma. BDP-HFA: beclomethasone dipropionate; ICS: inhaled corticosteroid; LABA: long-acting beta-2 agonist; LTRA: leukotriene receptor antagonist

(from NACA 2006²)

Surgical

There has been some very early work on destroying the muscle layer in the airways as a means of minimising asthma symptoms, but this is still experimental.

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

Dietary supplements

There has been much interest in whether specific dietary supplementation can influence the clinical course of asthma. Many entities and results have been examined but the authors of the studies are careful in making claims. One study showed that the lipid extract of New Zealand green-lipped mussel had a beneficial effect in patients with atopic asthma.¹⁸

Adolescents with a less nutritious diet, with a lower intake of antioxidants and anti-inflammatory micronutrients, have poorer pulmonary function and increased respiratory symptoms, especially among smokers. The likely explanation is that these nutrients promote respiratory health and lessen the effects of oxidative stress.¹⁹ Dietary supplementation or adequate intake of lycopene and foods rich in vitamin A may also be beneficial in asthma.²⁰

Acupuncture

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.

Alexander Technique

The Alexander Technique is a form of movement-based physical therapy. It is commonly used to correct posture and bring the body into natural alignment, and also as an aid to relaxation and greater body awareness. Although there are some positive findings, a review of trials found that there was not enough evidence to show a benefit of the Alexander Technique in reducing the need to use medication for asthma.²²

Herbal treatments

Evidence from 27 trials covering 21 different herbal treatments for both adults and children, and from both inpatient and outpatient settings, was inconclusive generally because of methodological limitations of the trials. Although further trials of high quality are needed to assess the use of herbal treatments in asthma, there is enough positive preliminary evidence to suggest that some of these compounds will prove to be of benefit.²³

Homeopathy

Different types of homeopathy are used for asthma, such as classical homeopathy (tailored to an individual’s bodily and psychological constitution and their symptoms) or isopathy (e.g. using a dilution of an agent that causes an allergy, such as pollen). In the existing studies on homeopathy and asthma, the type of homeopathy used varies and study designs are sometimes poor. Consequently, there is no strong evidence that homeopathy is effective for asthma.²⁴

Speleotherapy

Speleotherapy, or staying in an underground environment such as a cave or mine, is believed by some to be of benefit for people with asthma. If benefits are there, it is believed that they come from air quality, underground climate (cool and humid), air pressure or radiation. Evidence is more anecdotal than derived from high-quality randomised controlled trials.²⁵

ONGOING REVIEW AND/OR MONITORING

Asthma is a chronic disease and, as such, is worthy of regular planned medical review. However, it is the experience of many clinicians that people with asthma tend to view their asthma as an intermittent disease and so take medications and seek treatment only when they are particularly troubled by symptoms.

IMPORTANT PITFALLS

Making an accurate diagnosis of asthma can be particularly difficult in the paediatric age group, when the history and response to empirical treatment are the only guides. In the older patient, it is important to differentiate asthma from COPD (see below) but, at the same time, to be aware that some people have a mixed picture. If there is significant reversibility on spirometry (post-bronchodilator FEV₁ increases by 200 mL and 12%), treat as asthma.

PROGNOSIS

More children than adults manifest asthma and so the assumption is that, as a problem, asthma ‘weakens’ with age. It is probably better to accept the view of the National Asthma Council Australia that:²

education, together with self-monitoring, appropriate drug therapy, regular medical review and a written asthma action plan, reduces morbidity and mortality.

Most people with asthma lead normal lives and can participate competitively in sport.

PATIENT EDUCATION

There is a wealth of useful material available at the National Asthma Council Australia website (see Resources list).

CHRONIC OBSTRUCTIVE PULMONARY DISEASE

BACKGROUND AND PREVALENCE

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.