Bronchiectasis is a chronic disease of the lungs. It is caused by repeated damage to the airways of…
What is asthma?
Asthma is a common disease that affects the lungs. It causes the airways inside the lungs to become very sensitive to certain particles that are inhaled during breathing.
The main symptoms of asthma are episodes of wheezing, feeling out of breath, tightness in the chest and coughing. Some people with asthma may not experience very severe symptoms, but for others, it can be a major problem that interferes with daily activities and can lead to a life-threatening asthma attack.
There is no cure for asthma. However, with a proper medication plan and avoiding things that trigger asthma, most people with the condition can live a normal and active life.
In asthma, the airways are very sensitive to certain particles and irritants that enter the lungs. In healthy lungs, the airways that carry air into and out of the lungs are surrounded by muscle, which is usually relaxed and allows the airways to stay open to let air in and out.
During an asthma attack, certain particles that enter the lungs cause the airways to become inflamed, swollen and fill with mucus. The muscle surrounding them tightens, which causes the airways to narrow. This can make it difficult to breathe.
The triggers for asthma can vary from person to person and can depend on what type of asthma you have. Some triggers include:
- Airborne allergens such as pollen, pet hair and dust mites;
- Food allergens such as peanuts, eggs or dairy;
- Infections such as the common cold, flu and pneumonia;
- Cold air;
- Air pollution, including cigarette smoke;
- Some medications;
- Strong emotions and stress, and;
- Sudden changes in the weather or temperature.
There are some factors that can increase your chance of developing asthma. These include:
- Family history of asthma;
- A past history of allergic skin conditions (such as eczema) or hay fever;
- Passive and active smoking;
- Having a mother who smoked during pregnancy;
- Sensitivity to allergens, including airborne allergens and foods, and;
- Exposure to triggers in the workplace, such as chemicals and fumes.
There are several different types of asthma, which include:
Allergic asthma is the most common type. It is caused by an allergic reaction to certain particles that enter the lungs during breathing. These particles that can trigger the symptoms of asthma are known as allergens and include pet fur, pollens and dust mites, which can be found in mattresses, pillows and carpets. The symptoms of allergic asthma may start straight away, or several hours after allergen exposure.
Exercise-induced asthma is triggered by exercise or physical exertion. The airways begin to narrow 5-20 minutes after exercise begins. If you are diagnosed with asthma that is triggered by exercise, taking a preventer medication before exercise may be recommended to prevent the symptoms from occurring. In many cases, people with this type of asthma do not get symptoms when not exercising.
Cough-variant asthma is difficult to diagnose because the only symptom is a long-lasting dry cough. People with this type of asthma do not usually experience other signs of asthma, such as wheezing and difficulty breathing.
Work-related asthma is also sometimes called occupational asthma and is triggered or made worse by the work environment. This type of asthma is usually associated with workplaces that contain chemicals, smoke or fumes. As well as having the usual symptoms of asthma, people with work-related asthma may also experience nasal and eye irritation. Work-related asthma usually occurs at work and gets worse at the end of the work day or week.
Night-time asthma, also called nocturnal asthma, is when asthma attacks tend to occur between midnight and about 8am. It is not known why the asthma symptoms are worse in some people at night. Night-time asthma can occur on its own, or it may occur together with symptoms during the day.
Child-onset asthma is asthma that usually occurs during childhood. It occurs because a child becomes sensitive to common allergens in their environment. This type of asthma is linked to other allergic conditions such as hay fever and eczema and often runs in the family.
This term is used when a person is over 20 years old when they first develop asthma.
Signs and symptoms
Asthma symptoms vary from person to person. Some people have rare, mild asthma attacks, while others have more severe symptoms more often.
Early warning signs
If you have asthma, you may experience some early-warning signs that you are about to have an attack. These signs may include:
- Common cold symptoms (sneezing, headache, runny or congested nose, irritation of the throat);
- Trouble sleeping and tiredness;
- Increase in cough;
- Difficulty exercising, and;
- Poorer-than-normal lung function.
Recognising these early warning signs allows for early treatment, which may reduce the severity of the attack. These signs vary from person to person and may be noticed by the asthmatic, their friends or family.
Asthma attack symptoms
If you have an asthma attack you may experience:
- Shortness of breath;
- Chest tightness or pain;
- Poor lung function;
- Severe wheeze, either when breathing in or breathing out;
- Coughing that will not stop, and;
- Tight neck and chest muscles.
If action is taken when these symptoms first appear, a severe attack may be avoided.
Severe asthma attack symptoms
A severe asthma attack is a medical emergency. The symptoms of a very severe asthma attack may include:
- Increased coughing, breathlessness or chest tightness;
- Increased, or sometimes absent, wheezing;
- Difficulty speaking;
- Shallow breathing;
- Using other muscles to breathe, such as the neck muscles or shoulders;
- Grey or blue colour around the mouth and fingers;
- Pale complexion and sweating, and;
- Limited or no response to asthma medication.
Asthma symptoms in children
Asthma is very common in children. Children who have asthma can have very different symptoms. In children the symptoms can appear as:
- Frequent coughing spells;
- Less energy during play;
- Rapid breathing;
- Complaint of a tight chest or pain in the chest;
- Whistling or wheezing sound when breathing in or out;
- Laboured breathing;
- Shortness of breath, and;
- Tightened neck and chest muscles.
There are several conditions that have similar symptoms to asthma. These include heart failure and vocal cord dysfunction. If you experience asthma symptoms and don't respond to any of the normal asthma medications, these conditions may be investigated.
Methods for diagnosis
If your doctor suspects that you have asthma, they will ask you about your medical history, perform a physical examination and conduct some tests to measure your lung function.
A physical examination will likely involve assessment from the nose down to the chest and lungs. A stethoscope may be used to listen to chest sounds, although these may be normal when the patient is not having an asthma attack.
There are several types of breathing tests that can determine whether you have asthma. The first are tests that determine how well your lungs are working.
Spirometry is the most common breathing test. It is used to measure how well your lungs function, including how much air you can rapidly breathe out, the amount you can breathe in and if there are any changes after taking a medication commonly used to treat asthma.
A peak flow test is a simple test that measures how fast you breathe out. This test is performed using a peak flow meter, which is a small plastic tube that you blow into. It is also useful to see if you are responding to treatment. They can also be used every day at home to measure your lung function to work out if your asthma is getting worse, or if you may be about to have an asthma attack.
If simple spirometry and peak-flow tests do not clearly show whether your symptoms are caused by asthma, you may need to have a methacholine challenge. Methacholine is a bronchoconstrictor, which means it can cause your airways to narrow. People who have asthma are much more sensitive to methacholine than healthy people. To work out if you have asthma, lung function is measured before and after a fine mist of methacholine is inhaled. If asthma is present, lung function will usually drop by at least 20% after methacholine is given.
Less commonly used breathing tests include:
Bronchial provocation test
In a bronchial provocation test, your doctor will measure the level of airway narrowing before and after you perform strenuous physical activity, or take several breaths of cold air.
Exercise-induced bronchoconstriction test
To work out if you have exercise-induced asthma, your doctor may ask you to exercise and then measure your lung function.
A chest X-ray may occasionally be ordered to exclude other causes for symptoms, and/or to assess if a chest infection (pneumonia) may have triggered an asthma attack.
Types of treatment
Asthma is usually managed with a combination of medication and lifestyle changes.
The medication used to treat asthma can be divided into two main types.
Quick-relief medication is sometimes also called rescue medication. It works very quickly to open up the airways if you are having an asthma attack. It can also be used prior to exercise to prevent an attack if you get exercise-induced asthma. Quick-relief medication consists primarily of a class of medication known as short-acting beta-2 agonists, which include salbutamol, tetrabutaline and efometerol. These medications are usually taken via an inhaler, which is a device that helps medication get into your lungs. If you need to use quick-relief medication more than twice a week, your asthma may not be well controlled.
Preventer medications are used for the long-term control of asthma. They are slow-acting and, if used regularly, can prevent you from having an asthma attack, reduce the amount of wheeze, improve lung function and reduce the need for quick-relief medications. These are usually taken daily and often delivered via inhalers. Preventer medications can include corticosteroids (such as beclomethasone, budesonide, and fluticasone) and/or long-acting beta-2 agonists (such as salmeterol and formoterol). Other preventer medications that may be used to control asthma, particularly in children, include leukotriene antagonists (such as montelukast) and cromolyns (such as nedocromil).
Note on inhalers
Inhalers are an effective way of delivering medication directly to the airways and lungs, where they are needed. However, using inhalers can be confusing and difficult if you are not shown the correct technique. It is generally recommended that inhalers are used with a spacer, which is a device that helps mix the medications with air, prior to it being breathed in. It helps to deliver more of the medication to the airway and lungs, and less onto the tongue and mouth, which is not effective. Often your doctor, nurse or pharmacist will demonstrate the correct technique for using an inhaler when you are first prescribed them.
Prednisolone is a commonly used corticosteroid to help treat severe asthma, or attacks that do not respond to the other treatments. It works by reducing inflammation, which causes severe symptoms. It is usually given as a tablet that is taken for a few days until the condition improves. Long-term use is associated with certain adverse conditions.
Omalizumab is a specific medication used to treat moderate to severe allergic asthma. It works by blocking the immune system's natural response to allergens that trigger asthma. This is usually given as an injection once a week for a few months, then once a month for a period of 3-5 years. Other allergy medication that may be used to treat asthma includes oral and nasal spray antihistamines and decongestants.
Bronchial thermoplasty is a relatively new treatment for severe asthma. It involves reducing the amount of muscle that surrounds your airways, which limits the ability of your airways to tighten during an asthma attack. This makes breathing easier and may reduce the number of attacks. Bronchial thermoplasty treatment is not widely available and is used for very severe asthma that does not improve with inhaled corticosteroids or other long-term asthma medications.
Without proper treatment, asthma can be life-threatening, but with the right treatment, most people with the condition can lead normal lives. While there is no cure for asthma, sometimes the symptoms can improve over time. Half of the people who had asthma as a child no longer have the condition after a decade.
Asthma cannot be prevented, but there are several steps that can be taken to help manage asthma and reduce the frequency of attacks. These steps include:
- Getting healthcare professionals to work with you to form an action plan to educate you on how to take your medications and what to do if you are experiencing an asthma attack;
- Using a peak flow meter to measure your lung function, to work out if your lung function is getting worse and if you may be about to have an asthma attack;
- Getting flu and pneumonia vaccinations, to prevent getting these infections that can often trigger an asthma attack;
- Identifying and avoiding things that can trigger an asthma attack, such as smoking (quitting smoking);
- Taking medication as prescribed, as it is important to take asthma medication even if there are no symptoms present, and;
- Keeping a diary to help you recognise patterns of your asthma attacks and prevent them.