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Asthma

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Author - Dr. C. S. Ranaweera
Author 2 - Dr. E. A. L. Fernando (MD, FRCP) Consultant Pulmonologist

What is Asthma and Who Does it Affect?

Asthma is a condition that affects the smaller airways (bronchioles) of the lungs. From time to time the airways constrict (narrow) in people who have asthma. This causes the typical symptoms. The extent of the narrowing, and how long each episode lasts, can vary greatly.

Asthma can start at any age, but it most commonly starts in childhood. At least 1 in 10 children, and 1 in 20 adults, have asthma. Asthma runs in some families, but many people with asthma have no other family members affected.

The following diagram shows the structure of the lung, which is essential in respiration.

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What are the Symptoms of Untreated Asthma?

The common symptoms are cough and wheeze. You may also become breathless, and develop a feeling of chest tightness. Symptoms can range from mild to severe between different people, and at different times in the same person. Each episode of symptoms may last just an hour or so, or persist for days or weeks unless treated.

What are the typical symptoms if you have mild (untreated) asthma?

You tend to develop mild symptoms from time to time. For example, you may develop a mild wheeze and a cough if you have: a cold, a chest infection, be in the hay fever season, or when you exercise. For most of the time you have no symptoms. A child with mild asthma may have an irritating cough each night, but is often fine during the day.

What are the typical symptoms if you have moderate (untreated) asthma?

Without treatment: you typically have episodes of wheezing and coughing from time to time. Sometimes you become breathless. You may have spells, sometimes long spells, without symptoms. However, you tend to be wheezy for some of the time on most days. Symptoms are often worse at night, or first thing in the morning. You may wake some nights coughing or with a tight chest. Young children may not have typical symptoms. It may be difficult to tell the difference between asthma and recurring chest infections in young children.

What are the typical symptoms of a severe attack of asthma?

You become very wheezy, have a 'tight' chest, and have difficulty in breathing. You may find it difficult to talk because you are so breathless. Severe symptoms may develop from time to time if you normally have moderate symptoms. Occasionally, severe symptoms develop 'out of the blue' in some people who normally have just mild symptoms.

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What Causes Asthma?

Asthma is caused by inflammation in the airways. It is not known why the inflammation occurs. The inflammation irritates the muscles around the airways, and causes them to squeeze (constrict). This causes narrowing of the airways. It is then more difficult for air to get in and out of the lungs. This leads to wheezing and breathlessness. The inflammation also causes the lining of the airways to make extra mucus which causes cough and further obstruction to airflow. The following diagram

Asthma Attack

An acute exacerbation of asthma is commonly referred to as an asthma attack. The cardinal symptoms of an attack are shortness of breath (dyspnea), wheezing, and chest tightness.] Although the former is often regarded as the primary symptom of asthma, some people present primarily with coughing, and in the late stages of an attack, air motion may be so impaired that no wheezing is heard. When present the cough may sometimes produce clear sputum. The onset may be sudden, with a sense of constriction in the chest, as breathing becomes difficult and wheezing occurs (primarily upon expiration, but sometimes in both respiratory phases). It is important to note inspiratory stridor without expiratory wheeze however, as an upper airway obstruction may manifest with symptoms similar to an acute exacerbation of asthma, with stridor instead of wheezing, and will remain unresponsive to bronchodilators.

Signs of an asthmatic episode include wheezing, prolonged expiration, a rapid heart rate (tachycardia), and rhonchous lung sounds (audible through a stethoscope). During a serious asthma attack, the accessory muscles of respiration (sternocleidomastoid and scalene muscles of the neck) may be used, shown as in-drawing of tissues between the ribs and above the sternum and clavicles, and there may be the presence of a paradoxical pulse (a pulse that is weaker during inhalation and stronger during exhalation), and over-inflation of the chest.

During very severe attacks, an asthma sufferer can turn blue from lack of oxygen and can experience chest pain or even loss of consciousness. Just before loss of consciousness, there is a chance that the patient will feel numbness in the limbs and palms may start to sweat. The person's feet may become cold. Severe asthma attacks which are not responsive to standard treatments, called status asthmaticus, are life-threatening and may lead to respiratory arrest and death.

Though symptoms may be very severe during an acute exacerbation, between attacks a patient may show few or even no signs of the disease.

Cause

Asthma is caused by environmental and genetic factors which can influence how severe asthma is and how well it responds to medication.  Some environmental and genetic factors have been confirmed by further research, while others have not been. Underlying both environmental and genetic factors is the role of the upper airway in recognizing the perceived dangers and protecting the more vulnerable lungs by shutting down the airway. Margie Profet has argued that allergens look to our immune systems like significant threats. Asthma, in this view, is seen as an evolutionary defense. This view also suggests that removing or reducing airborne pollutants should be successful at reducing the problem.

Environmental

Many environmental risk factors have been associated with asthma development and morbidity in children.

Environmental tobacco smoke, especially maternal cigarette smoking, is associated with high risk of asthma prevalence and asthma morbidity, wheeze, and respiratory infections. Low air quality, from traffic pollution or high ozone levels, has been repeatedly associated with increased asthma morbidity and has a suggested association with asthma development that needs further research.

Recent studies show a relationship between exposure to air pollutants (e.g. from traffic) and childhood asthma. This research finds that both the occurrence of the disease and exacerbation of childhood asthma are affected by outdoor air pollutants.

Viral respiratory infections are not only one of the leading triggers of an exacerbation but may increase one risk of developing asthma.

Psychological stress has long been suspected of being an asthma trigger, but only in recent decades has convincing scientific evidence substantiated this hypothesis. Rather than stress directly causing the asthma symptoms, it is thought that stress modulates the immune system to increase the magnitude of the airway inflammatory response to allergens and irritants.

Antibiotic use early in life has been linked to development of asthma in several examples; it is thought that antibiotics make one susceptible to development of asthma because they modify gut flora, and thus the immune system (as described by the hygiene hypothesis). The hygiene hypothesis is a hypothesis about the cause of asthma and other allergic disease, and is supported by epidemiologic data for asthma. For example, asthma prevalence has been increasing in developed countries along with increased use of antibiotics, c-sections, and cleaning products. All of these things may negatively affect exposure to beneficial bacteria and other immune system modulators that are important during development, and thus may cause increased risk for asthma and allergy.

Recently scientists connected the rise in prevalence of asthma, to the rise in use of paracetamoll, suggesting the possibility that paracetamol can cause asthma.

It has been suggested that viral infections such as HSV, VSV and CSV are correlated to asthma episodes

Genetic

Over 100 genes have been associated with asthma in at least one genetic association study. However, such studies must be repeated to ensure the findings are not due to chance. Through the end of 2005, 25 genes had been associated with asthma in six or more separate populations:

Myths, Facts, and Statistics About Asthma

Before we present the typical symptoms of asthma, we should dispel some common myths about this condition. This is best achieved by conducting a short true or false quiz.

  1. T or F - Asthma is "all in the mind."
  2. T or F - You will "grow out of it."
  3. T or F - Asthma can be cured, so it is not serious and nobody dies from it.
  4. T or F - You are likely to develop asthma if someone in your family has it.
  5. T or F - You can "catch" asthma from someone else who has it.
  6. T or F - Moving to a different location, such as the desert, can cure asthma.
  7. T or F - People with asthma should not exercise.
  8. T or F - Asthma does not require medical treatment.
  9. T or F - Medications used to treat asthma are habit-forming.
  10. T or F - Someone with asthma can provoke episodes anytime they want in order to get attention.

Here are the Answers:

  1. F - Asthma is not a psychological condition. However, emotional triggers can cause flare-ups.
  2. F - You cannot outgrow asthma. In about 50% of children with asthma, the condition may become inactive in the teenage years. The symptoms, however, may reoccur anytime in adulthood.
  3. F - There is no cure for asthma, but the disease can be controlled in most patients with good medical care. The condition should be taken seriously, since uncontrolled asthma may result in emergency hospitalization and possible death.
  4. T - You have a 6% chance of having asthma if neither parent has the condition, a 30% chance if one parent has it, and a 70% chance if both parents have it.
  5. F - Asthma is not contagious.
  6. F - A new environment may temporarily improve asthma symptoms, but it will not cure asthma. After a few years in the new location, many people become sensitized to the new environment and the asthma symptoms return with the same or even greater intensity than before.
  7. F - Swimming is an optimal exercise for those with asthma. On the other hand, exercising in dry, cold air may be a trigger for asthma in some people.
  8. F - Asthma is best controlled by having an asthma management plan designed by your doctor that includes the medications used for quick relief and those used as controllers.
  9. F - Asthma medications are not addictive.
  10. F - Asthma attacks cannot be faked. In rare cases, there is a psychological condition known by a variety of names (factious asthma, spastic dysphonia, globus hystericus) where emotional issues may cause symptoms that mimic the symptoms of asthma

 

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What Can Make Asthma Symptoms Worse?

Asthma symptoms may flare up from time to time. There is often no apparent reason why symptoms flare up. However, some people find that symptoms are triggered, or made worse, in certain situations. It may be possible to avoid certain triggers which may help to reduce symptoms. Things that may trigger asthma symptoms include the following.

  • Infections. Particularly colds, coughs, and chest infections.
  • Pollens and moulds. Asthma is often worse in the hay fever season.
  • Exercise. However, sport and exercise are good for you if you have asthma. If necessary, you can use an inhaler before exercise to prevent symptoms from developing. But, as a rule, exercise-induced asthma often represents under-treated asthma. If it occurs it may indicate a need to step up your usual preventer treatment (see below).
  • Certain drugs. For example, about 1 in 50 people with asthma are allergic to aspirin which can trigger symptoms. Other drugs that may cause asthma symptoms include: anti-inflammatory painkillers such as ibuprofen (eg Neurofen®), diclofenac, etc, and beta-blockers such as propranolol, atenolol, or timolol. This includes beta-blocker eye-drops used to treat glaucoma.
  • Smoking and cigarette fumes. If you smoke and have asthma, you should make every effort to stop. See a practice nurse for help if you find it difficult. 'Passive' smoking can make asthma worse too. Even where adults smoke away from the presence of children, smoke on clothes, hair, etc, may make asthma worse. All children deserve to live in a smoke-free home. In particular, children with asthma.
  • Other fumes and chemicals. For example, fumes from paints, solvents and pollution. The increase in air pollution may be a reason why asthma is becoming more common.
  • Emotion. Asthma is not due to 'nerves', but such things as stress, emotional upset, or laughing may trigger symptoms.
  • Allergies to animals. Such as pet cats, dogs, and horses. Animals do not trigger symptoms in most cases, but some people notice that their symptoms become worse when close to certain animals.
  • House dust mite. This is a tiny creature that lives in mattresses and other fabrics around the home. If you are allergic to it, it may make symptoms worse. It is impossible to get rid of house dust mite completely. To greatly reduce their number takes a lot of time and effort and involves: using special mattress covers, removing carpets, removing or treating soft toys, etc. However, if symptoms are difficult to control with treatment, and you are confirmed to be allergic to house dust mite, then it may be worth considering trying to reduce their number. See separate leaflet called 'Allergy to House Dust Mite and Pets'.
  • Some foods. This is uncommon. Food is not thought to be a trigger in most cases.

Some people only develop symptoms when exposed to a certain 'trigger'. For example, exercise-induced asthma. As mentioned above, exercise can make symptoms worse for many people with asthma. But, some people only develop symptoms when they exercise, and are fine the rest of the time. Another example is that some people only develop symptoms when exposed to specific chemicals.

 

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How is Asthma Diagnosed?

Sometimes symptoms are typical, and the diagnosis is easily made by a doctor.

If there is doubt then some simple tests may be arranged. A peak flow meter is commonly used to help confirm that symptoms are due to asthma (see below). Sometimes a test called spirometry may be done to confirm the diagnosis. This involves breathing into a machine that measures the rate and volume of airflow in and out of your lungs.

 

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What are the Treatments for Asthma?

For most people with asthma, most of the symptoms can be prevented with treatment. So, you are able to get on with normal life, school, work, sport, etc.

Inhalers

Most people with asthma are treated with inhalers. Inhalers deliver a small dose of drug directly to the airways. The dose is enough to treat the airways. However, the amount of drug that gets into the rest of your body is small so side-effects are unlikely, or minor. There are various inhaler devices made by different companies. Different ones suit different people. A doctor or nurse will advise on the different types. See separate leaflet called 'Asthma - Inhalers' for more details.

Drugs delivered by inhalers can be grouped into 'relievers', 'preventers' and 'long acting bronchodilators'.

  • A reliever inhaler is taken 'as required' to ease symptoms. The drug in a reliever inhaler relaxes the muscle in the airways. This makes the airways open wider, and symptoms usually quickly ease. These drugs are also called 'bronchodilators' as they dilate (widen) the bronchi and bronchioles (airways). There are several different reliever drugs. For example, salbutamol and terbutaline. These come in various brands made by different companies. If you only have symptoms every 'now and then', then the occasional use of a reliever inhaler may be all that you need. However, if you need a reliever inhaler three times a week or more to ease symptoms, a preventer inhaler is usually advised.
  • A preventer inhaler is taken every day to prevent symptoms from developing. The drug commonly used in preventer inhalers is a steroid. There are various brands. Steroids work by reducing the inflammation in the airways. When the inflammation has gone, the airways are much less likely to become narrow and cause symptoms. It takes 7-14 days for the steroid in a preventer inhaler to build up its effect. Therefore, it will not give any immediate relief of symptoms. However, after a week or so of treatment, the symptoms have often gone, or are much reduced. It can take up to six weeks for maximum benefit. You should then continue with the preventer inhaler every day even when your symptoms have gone - to prevent symptoms from coming back. You should then not need to use a reliever inhaler very often, (if at all).
  • A long acting bronchodilator may be advised in addition to a preventer inhaler. One may be needed if symptoms are not fully controlled by the preventer inhaler alone. The drugs in these inhalers work in a similar way to 'relievers', but work for up to 12 hours after taking each dose. They include salmeterol and formoterol. (Some brands of inhaler contain a steroid plus a long acting bronchodilator for convenience.)

Spacer devices are used with some types of inhaler. They are commonly used by children, but many adults also use them. A spacer is like a small plastic chamber that attaches to the inhaler. It holds the drug like a reservoir when the inhaler is pressed. A valve at the mouth end ensures that the drug is kept within the spacer until you breathe in. When you breathe out, the valve closes. So, you don't need to have good co-ordination to inhale the drug if you use a spacer device. A face mask can be fitted onto some types of spacers, instead of a mouthpiece. This is sometimes done for young children and babies who can then use the inhaler simply by breathing in and out normally through the mask.

Tablets to Open up the Airways

Most people do not need tablets as inhalers usually work well. However, in some cases a tablet (or in liquid form for children) is prescribed in addition to inhalers if symptoms are not fully eased by inhalers alone. Some young children use liquid medication instead of inhalers.

Steroid Tablets

A short course of steroid tablets (such as prednisolone) is sometimes needed to ease a severe or prolonged attack of asthma. Steroid tablets are good at reducing the inflammation in the airways. For example, a severe attack may occur if you have a cold or chest infection.

Some people worry about taking steroid tablets. However, a short course of steroid tablets (for a week or so) usually works very well, and is unlikely to cause side-effects. Most of the side-effects caused by steroid tablets occur if you take them for a long time (more than several months), or if you take frequent short courses of high doses.

 

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What are the Dosages of Treatment?

Everyone is different. The correct dose of a preventer inhaler is the lowest dose that prevents symptoms. A doctor may prescribe a high dose of a preventer inhaler at first, to quickly "get on top of symptoms". When symptoms have gone, the dose may then be reduced by a little every few weeks. The aim is to find the lowest regular dose that keeps symptoms away.

Some people with asthma put up with symptoms. They may think that it is normal to still have some symptoms even when they are on treatment. A common example is a night time cough which can cause disturbed sleep. But if this occurs and your symptoms are not fully controlled - tell your doctor or nurse. Symptoms can often be prevented. For example, by adjusting the dose of your preventer inhaler, or by adding in a long acting bronchodilator.

 

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A 'Typical' Treatment Plan

A common treatment plan for a 'typical' person with moderate asthma is:

  • A preventer inhaler (usually a steroid inhaler), taken each morning and at bedtime. This usually prevents symptoms throughout the day and night.
  • A reliever inhaler may be needed now and then if breakthrough symptoms occur. For example, if symptoms flare up when you have a cough or cold.
  • If exercise or sport causes symptoms, then a dose of a reliever inhaler just before the exercise usually prevents symptoms.
  • The dose of the preventer inhaler may need to be increased for a while if you have a cough or cold, or during the hay fever season.
  • Some people may need to add in a long acting bronchodilator, or tablets, if symptoms are not controlled with the above.

At first, adjusting doses of inhalers is usually done on the advice of a doctor or nurse. In time, you may agree an 'asthma action plan' with your doctor or nurse. This means that you make adjustments to the dose of your inhalers, depending on your symptoms and/or peak flow readings.

 

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Does Asthma go Away?

There is no once-and-for-all cure. However, about half of the children who develop asthma 'grow out of it' by the time they are adults.

For many adults, asthma is variable with some good spells and some spells that are not so good. Some people are worse in the winter months, and some worse in the hay fever season. Although not curable, asthma is treatable. Stepping up the treatment for a while during bad spells will often control symptoms.

 

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Some Other General Points About Asthma

It is vital that you learn how to use your inhalers correctly. In some people, symptoms persist simply because they do not use their inhaler properly, and the drug from the inhaler does not get into the airways properly. See your practice nurse or doctor if you are not sure if you are using your inhaler properly.

See a doctor or nurse if symptoms are not fully controlled, or if they are getting worse. For example, if:

  • a night time cough or wheeze is troublesome
  • sport is being affected by symptoms
  • your peak flow readings are lower than normal
  • you need a reliever inhaler more often than usual

An adjustment in inhaler timings or doses may control these symptoms.

See a doctor urgently if you develop severe symptoms that are not eased by a reliever inhaler. In particular, if you have difficulty talking due to shortness of breath. You may need emergency treatment with high dose reliever drugs and other treatments, sometimes in hospital. A severe asthma attack can be life-threatening.

 

Prevention

Trigger Rvoidance

  • As is common with respiratory disease, smoking is believed to adversely affect patients in several ways, including an increased severity of symptoms (likely due to increased inflammation[91]), a more rapid decline of lung function, and decreased response to preventive medications.[92] Automobile emissions are considered an even more significant cause and aggravating factor.[citation needed] Patients with asthma who smoke or who live near traffic[citation needed] typically require additional medications to help control their disease. Furthermore, exposure of both non-smokers and smokers to second-hand smoke is detrimental, resulting in more severe asthma, more emergency room visits, and more asthma-related hospital admissions, but the effect of woodstove and gas stove fumes is uncertain.[93] Smoking cessation and avoidance of second-hand smoke is strongly encouraged in people who have asthma.[94] Air filters and room air cleaners may help prevent some asthma symptoms.[95] Ozone is also considered as a major factor in increasing asthma.[96] The report by the National Heart, Lung and Blood Institute [97] supports the idea of an asthma management plan that includes the avoidance of as many allergens as possible to which the individual is sensitive. This report, and others [98][99] also agree that no one single approach is sufficient to reduce allergens; a multifactorial approach is required. The Asthma and Allergy Friendly Certification Program that is operated in the USA by the Asthma and Allergy Foundation of America and in Canada by the Asthma Society of Canada [1] is based on this multifactorial approach to trigger control.
  • For those in whom exercise can trigger an asthma attack (exercise-induced asthma), higher levels of ventilation and cold, dry air tend to exacerbate attacks. For this reason, activities in which a patient breathes large amounts of cold air, such as skiing and running, tend to be worse for people with asthma, whereas swimming in an indoor, heated pool with warm, humid air is less likely to provoke a response.[16]

 

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Last update on : 2011-03-23 12:04:54