Thursday February 9, 2017
Asthma is a very common long-term condition, with around 1 in 12 adults in the UK living with it. Many of our patients at London Doctors Clinic suffer with asthma, whether that's noted as part of a patient's medical history, or whether that's the main reason for the consultation. But how much do you actually know about asthma?
Asthma is an inflammatory condition which is estimated to affect around 250 million people in the world. It affects the lungs, leading to increased contraction of the smooth muscle lining the bronchi, causing shortness of breath, difficulty breathing, and coughing. The symptoms associated with asthma usually begin in childhood, and are associated with a combination of genetic and environmental factors. The environmental factors include allergens and air pollution, and triggers such as cold air, exercise, and medication, and the symptoms are typically worse early in the morning and at night.
Causes of Asthma
Although the cause of asthma is thought to be a combination of genetic and environmental factors, the way that these interact to cause the condition is unknown. Generally, it is believed that asthma in patients younger than 12 is more likely due to genetic factors, whereas asthma which begins in patients older than 12 is more likely due to environmental factors.
Family history is definitely an important risk factor for the development of asthma, since if one identical twin has asthma, the chance of the other twin developing it in their lifetime is 25%. Additionally, genes which are involved in the immune system and inflammation have also been linked with asthma. Furthermore, the hereditary medical condition of atopy involves the development of eczema and hay fever in childhood, which gradually progresses into the development of asthma.
The hereditary medical condition of atopy involves the development of hay fever in childhood, which progresses into asthma
However, environmental factors are also important as a cause of asthma. These include smoking during pregnancy, pollution from traffic or low ozone levels, and indoor allergens such as dust mites and animal fur. Childhood respiratory infections by viruses such as respiratory syncytial virus and rhinovirus are thought to also increase the risk.
The number of cases of asthma has been rising steadily worldwide, and one suggestion why this might be the case is the hygiene hypothesis. This states that increased cleanliness and decreased family size in modern society means that children are exposed to certain non-pathogenic bacteria later on in life, which may lead to asthma like symptoms. Exposure to these bacteria earlier in life may prevent the development of asthma, supported by evidence that families with pets have a lower incidence of asthma, and delivery via caesarean section (which prevents colonisation by bacteria from passage through the birth canal) is associated with an increased risk of asthma.
These genetic and environmental risk factors predispose individuals to asthma, and these changes lead to inflammation of the wall lining the bronchi and bronchioles of the lung, resulting in increased contractility of the smooth muscles surrounding them, and therefore narrowing of the bronchi. This leads to the symptoms of wheezing, breathlessness, coughing, and a feeling of tightness around the chest. However, these symptoms are usually temporary, and get better by themselves.
In asthma, symptoms will be stable for most of the time, but may suddenly exacerbate into acute episodes, known as an asthma attack. These episodes can be triggered by factors including stress, exercise, infections, perfumes, animal fur and dust. This is characterised by symptoms that do not get better, breathlessness to the extent that it interferes with speaking or eating, and increased heart rate to compensate for the lack of oxygen.
Asthma attacks can be potentially life threatening, and symptoms associated with severe acute asthma attacks include blue lips and fingernails, tightened neck and chest muscles, low blood pressure and arrhythmia. Lungs may tighten to the extent that there is not enough air movement to cause wheezing, resulting in a “silent chest”. This is a medical emergency and patients suffering from a severe asthma attack need to be taken to the hospital immediately.
Asthma is suspected when the pattern of symptoms above have been reported, and worsen due to triggers such as exercise, stress and infections. Spirometry is then used to confirm the diagnosis. This involves the patient taking the deepest breath they can and exhaling, to measure the forced expiratory volume capacity of the lungs (FEV1). First the patient is asked to do the test without any medication, then the test is repeated after administration of salbutamol, a bronchodilator. If the FEV1 improves by more than 12% after salbutamol, this supports the diagnosis.
There is no current cure for asthma, but the symptoms associated with asthma can be managed. Lifestyle modifications can be put into place to reduce exposure to triggers such as pet fur and cigarette smoke. For patients with mild, occasional attacks, the first line treatment involves short-acting beta 2-adrenoceptor agonists (SABA), such as salbutamol, given through an inhaler (usually blue in the UK). If the patient cannot tolerate SABA, then an anticholinergic such as ipratropium bromide is used instead.
Inhalers are often administered to treat asthma
If the disease is more persistent and long term control is needed, low-dose inhaled corticosteroids, such as beclomethasone, is given twice daily through an inhaler (usually red in the UK) this may be used in conjunction with long-acting beta 2-adrenoceptor agonists (LABA), oral leukotriene antagonists such a montelukast, or a mast cell stabiliser. With treatment, the outcome for patients with asthma is generally good, and the mortality rates worldwide from asthma has been decreasing steadily.
If you want to find out more about asthma, why come and see one of our private doctors? With eight London clinics - and a ninth opening this month (Paddington clinic) - we can help you find a GP near you. And if you're looking for a same day doctor London Doctors Clinic is here for you! Book today!
By Jennie Han