Asthma is a widespread persistent inflammatory condition of the lung airways whose cause is not totally understood. It's a disorder of the respiratory system in which the passage of air to the lungs sporadically narrow causing coughing, wheezing, and shortness of breath which often worsens at night. This tightening is typically short-term and reversible, but in severe attacks, asthma can result in death.
The term Asthma most frequently refers to bronchial asthma, another inflammation of the airways, but it is also used to refer to cardiac asthma, which develops when fluid builds up in the lungs as a complication of heart failure.
Asthma causes inflammation of the airways airflow into and out of the lungs. The muscles of the bronchial tree become taut and the lining of the air passages to enlarge, which reduces airflow and produces the characteristic asthmatic wheezing sound.
An asthma attack, can also occur as an allergic reaction to an allergen or other substance (acute asthma), or as a part of a complex disease cycle which includes reactions to stress or exercise (chronic asthma).
Alternate Names For Asthma Include
Bronchial Asthma, Exercise Induced Asthma - Bronchial, Reactive Airways Disease (RAD)
Chronic Asthma
In chronic asthma, inflammation can be accompanied by irreparable airflow limitation. In pre-school children underlying pathology may not exhibit considerable bronchial hyper reactivity, and there is also no evidence chronic inflammation is a basis for the episodic wheezing which is associated with viral infections.
Characteristic Features of Chronic Asthma
These include an alteration of the construction and functions of elements of the airways. Together, these structural changes interact with the inflammatory cells and mediators to cause the characteristic features of the disease.
Occurrence
Asthma occurs in both males and females of all ages, racial groups, and socioeconomic levels. it is also found Asthma is usually more common in poor built-up neighbourhoods, and in cold climates, and developed countries, but this is probably due to the poor living conditions of the asthmatic sufferers.
Research suggests genetic factors can also increase the risk of developing asthma, and children with a family history of asthma are more likely to develop the disease than other children. However many people with no family history of asthma can also develop the disorder.
Prevalence Of Asthma
In many countries the frequency of asthma is increasing, particularly in the second decade of life where it affects 10-15% of the population. There is also a noted geographical variation, with asthma being common in more urbanized countries.
Some of the highest rates of Asthma are countries such as New Zealand and Australia, but it is much rarer in Far Eastern countries such as China, Malaysia, Africa and Central and Eastern Europe.
Having said that however long-term follow-up in these developing countries suggests asthma problems may become more frequent as the population becomes more 'westernized'.
Studies of occupational asthma suggest a high proportion of the workforce, perhaps up to 20%, may become asthmatic if exposed to potent sensitizers.
Asthma has three characteristics:
- airflow limitation,
- airway hyper responsiveness,
- Inflammation of the bronchi with its associated plasma exudation, oedema, and smooth muscle hypertrophy, mucus plugging and epithelial damage.
Asthma can be divided into:
Extrinsic - implying a definite external cause
Intrinsic - when no causative means can be identified.
Extrinsic asthma
This occurs most regularly in individuals who show a positive skin-prick reaction to universal inhalant allergens. Positive skin-prick tests to these inhalant allergens are shown in 90% of children with persistent asthma. Interestingly though only 50% of adults veer towards this trend.
Intrinsic asthma
This usually starts in middle age, though many sufferers with adult-onset asthma show positive skin tests and on closer questioning often give a history of respiratory symptoms which are compatible with childhood asthma.
Asthma Attacks
Asthma attacks occur when the bronchi and bronchioles become inflamed, this reduces the space throughout which air travels through the lungs. This causes the asthmatic victim to work harder to move air in and out of their lungs.
Asthma attacks usually begin with a dry cough and mild chest heaviness. As an attack grows, wheezing develops and increases in pitch; breathing becomes more difficult and coughing produces thick, stringy mucus.
As the airway irritation prevents some of the oxygen-rich air from reaching the alveoli in the lungs, the cells of the body start burning oxygen at a higher rate, which increases the body’s demand for oxygen.
The frequency of asthma attacks varies considerably among asthma suffers. Some people have daily attacks, while others can go months or even years without having an attack.
Narrowing of Airways in Asthma
People with asthma have extra responsive or hyper responsive airways. Their airways react by contracting or obstructing when they become irritated. This makes it difficult for them to move air in and out of their lungs.
This narrowing or obstruction is caused by:
- Airway inflammation (the airways in the lungs become red, swollen and narrow)
- Broncho-constriction (the muscles encircling the airways tighten or go into spasm)
Airway Inflammation
If a normal airway has been exposed to certain stimulus (i.e. inhaled allergen like grass pollen), it becomes inflamed, swollen and plugged with mucus. This makes the airway opening smaller and more difficult for air to get through. It's easy to see why children, who have small airways to begin with, would have difficulty breathing if this happens.
Broncho-constriction
If the opening of a typical airway is exposed to certain stimuli (such as cold air or enthusiastic exercise), the muscle fibres surrounding the airway contract thus making the airway opening even smaller. This makes breathing for the sufferer much more difficult.
Causes Of Asthma
Asthma attacks are caused by airway hyper receptiveness. The most common causes of an asthma attack are very small lightweight particles transported through the air and inhaled into the lungs.
When they enter the airways, these particles which are known as environmental triggers, cause an inflammatory reaction in the airway walls which results in asthma attack.
Allergens
For some people environmental triggers are allergens. These are natural substances, such as plant pollen and mould spores, animal dander (tiny pieces of animal hair and skin), and faecal material from dust mites and cockroaches.
Allergens produce an inflated response of the immune system in which a specific antibody immunoglobulin E, initiates an inflammatory response. These same allergens usually cause little or no response in non-allergic people.
The allergens involved in asthma are similar to those in rhinitis. The particle size of pollens (>20 microns) mean they are more likely to cause conjunctivitis, rhinitis and pharyngitis as well as asthma. Allergens from faecal particles of the house-dust mite are the most important extrinsic cause of asthma world-wide.
Chemical Irritants
Chemical irritants trigger an inflammatory response differently to allergen-triggered asthma.
Some people are sensitive to common chemical irritants, such as perfume, hairspray, make-up, and household cleaners.
Other chemical irritants include industrial chemicals and plastics, as well as many forms of air pollution, such as exposure to high levels of ozone, car exhaust, wood smoke, and sulphur dioxide.
Physiological Triggers
Aggravation from within the body is known as physiological triggers and includes exercise and infections, such as the common cold. Sometimes eating certain types of food can cause an asthma attack.
Chemicals found in food or drugs such as aspirin and ibuprofen can be especially problematic for many asthma sufferers. Emotions, such as expressions of grief, shouting, or laughing, can also provoke rapid inhalation of oxygen causing the airways to narrow which trigger an attack. Many asthmatics are especially responsive to physical exercise in cold weather.
Causes and triggers of asthma
Those people who readily develop antibodies of IgE class against common materials present in the environment can also develop asthma.
Such antibodies are present in 30-40% of the western population, and there is a link between serum IgE levels and both the prevalence of asthma and airway responsiveness to histamine or methacholine.
Genetic and environmental factors affect serum IgE levels and may turn out to play a key role in the development of asthma.
Early childhood exposure to allergens and maternal smoking can also cause IgE production. It has been suggested growing up in a relatively clean environment can predispose towards an IgE response to allergens. On the other hand, growing up in a dirtier environment may allow the immune system to avoid developing allergic responses!
Occupational sensitizers
Over 200 materials encountered in the workplace are recognized as giving rise to occupational asthma. These are usually recognized as occupational diseases in the western world.
Asthma sufferers in insurable employment who can prove their workplace contributed to their condition are eligible for statutory compensation provided they apply within 10 years of leaving the occupation in which the asthma developed (UK).
The risk of developing occupational asthma increases in smokers.
The proportion of workers developing occupational asthma depends on their exposure, so the correct enclosure of industrial processes and appropriate ventilation can greatly reduce the risk of contracting Asthma
Non-specific factors
Characteristic feature of bronchial hyper reactivity in asthmatics mean as well as reacting to specific antigens their airways will also respond to a wide variety of non-specific stimuli.
Cold air and exercise
Many asthmatics may experience an attack of wheezing after they have completed prolonged or non-stop exercise especially in a cold environment. The attack doesn't occur during the middle of their exercise period but towards the end. The inhalation of cold, dry air can also cause an asthmatic attack.
Environmental Pollution
Contact with cigarette smoke, car exhaust fumes, strong perfumes or high concentrations of dust in the atmosphere can be strong factors in causing an asthmatic attack.
Epidemics
Major epidemics of asthma have been recorded when large amounts of allergens have been released into the air, (e.g. there was a soy bean epidemic in Barcelona.)
Further insignificant epidemics of asthma have occurred during periods of heavy atmospheric contamination in industrialized areas which is caused by the presence of high concentrations of sulphur dioxide, ozone and nitrogen dioxide in the air.
Food
Certain foods such as wine can trigger an asthma attack.
Emotion
Asthma is also influenced by certain emotions such as laughing, crying etc. But there is no proof people with asthma are any more psychologically disturbed than their non-asthmatic peers.
Drugs Used with Asthma
Non-steroid anti-inflammatory drugs (NSAIDs). NSAIDs, chiefly aspirin, have a major role in the development and precipitation of attacks in approximately 5% of people with asthma.
Immediate asthma
This is the most common response. An attack begins within minutes of contact with the allergen, reaches its maximum in 15-20 minutes and subsides after 1 hour.
Late-phase reactions
Following an instantaneous reaction many asthmatics may develop more prolonged and sustained attacks that respond inadequately to the inhalation of bronchodilator drugs.
Dual asthmatic response
This is a combination of an early reaction followed by a late reaction.
Recurrent asthmatic reactions
Development of a late-phase response is associated with increases in underlying level of airway hyper reactivity that individuals can show with systematic episodes of asthma on subsequent days.
Asthma Symptoms & Signs
Clinical features
People experiencing asthma exhibit symptoms virtually identical to those suffering from airflow limitation which is caused by COPD. (Chronic Obstructive Airways Disease). The symptoms for both are usually worse during the night.
Wheezing attacks and shortness of breath are more or less universal in both conditions. A cough is a frequent symptom that will often predominate, and can often be misdiagnosed as another respiratory disorder.
There are many variations in the regularity and duration of asthmatic attacks. Some individuals have only one or two attacks a year lasting a few hours, whilst others may have attacks lasting for weeks.
Unfortunately asthma is a major cause of impaired quality of life. It has an impact on work as well as recreational and physical activities and emotions.
Symptoms of Asthma
· wheezing which
o usually begins suddenly
o is episodic
o may be worse at night or in early morning
o is aggravated by exposure to cold air
o is aggravated by exercise
o is aggravated by heartburn
o resolves spontaneously
o is relieved by bronchodilators
Other Symptoms include
· cough with or without sputum (phlegm) production
· shortness of breath which is aggravated by exercise
· breathing requiring increased work
· intercostals retractions (pulling of the skin between the ribs when breathing)
Emergency Symptoms of Asthma
· acute difficulty in breathing
· bluish colour to lips and face
· severe apprehension
· fast pulse
· sweating
· decreased level of consciousness (severe drowsiness or confusion) during the asthma attack
· Death
Additional symptoms associated with asthma
· nasal flaring
· chest pain
· tightness in the chest
· an abnormal breathing pattern, in which exhalation (breathing out) takes more than twice as long as inspiration (breathing in)
· breathing which temporarily stops
· coughing up blood
Asthma Diagnosis & Tests
Physicians typically diagnose asthma by looking for characteristic symptoms such as intermittent problems with breathing which can include wheezing, coughing, and shortness of breath. When these symptoms alone fail to establish a diagnosis of asthma, doctors will usually use spirometry testing.
Trigger Identification
Identifying a specific trigger of a person's asthma is frequently more difficult than an initial diagnosis. An asthma sufferer might develop an asthma attack when using a particular cosmetic or household cleaning product. So when triggers are difficult to identify, a series of allergy skin tests are useful to determine what they are.
Correct Diagnosis
Making a correct diagnosis is tremendously important because if asthma is correctly diagnosed it can be treated more appropriately.
A diagnosis of asthma involves all of the following:
A detailed history which would include:
o A family history of asthma, allergies, hay fever and eczema; children will have a greater chance of developing the above if there is a family history of allergies and asthma
o A child's medical history including:
§ When parents first noticed the child developed breathing problems; history of nasal stuffiness (rhinitis), itchy eyes (allergic conjunctivitis) and eczema, which are common accompaniments to asthma, and hives (urticaria).
§ A history of recurrent and persistent cough following a cold, frequent colds, croup, seasonal changes (i.e. worse in the spring and autumn), exercise limited by breathing problems, waking at night with symptoms.
§ school absences, emergency room visits (hospitalizations)
§ environmental history
2. Physical examination: i.e. listening to the lungs with a stethoscope; examination of nasal passages etc.
3. Chest x-ray to exclude the likelihood of breathing problems being caused by something other than asthma.
4. Blood tests and sputum studies.
5. Allergy prick skin testing: Skin tests can confirm a presence or absence of allergies; but they must, be correlated to the history of symptoms shown.
6. Spirometry If testing children who are less than five years old, this test is not commonly indicated because a certain amount of effort and cooperation is required. However, it's a very good trustworthy method of making an asthma diagnosis. Any difficult or troublesome asthma should be confirmed objectively by performing a spirometry test.
7. Challenge tests: Exercise challenge tests and methacholine inhalation tests are procedures which are used most frequently in clinical laboratories to assess airway responsiveness.
8. Differential diagnosis: Other possible causes of shortness of breath, wheeze, and cough plus chest tightness need to be investigated in order to rule them out. These can include such illnesses as heart disease, other lung conditions and gastro-oesophageal reflux.
- A trial use of asthma medications: If asthma medications are taken and an improvement in symptoms is seen this further supports a diagnosis of asthma.
Tests may include:
· Peak expiratory flow charts
- Exercise tests
- Histamine or methacholine bronchial provocation test
- A trial of corticosteroids
- Blood and sputum tests
- Chest X-ray
- Skin tests
- Allergen provocation tests
Peak expiratory flow charts
Measurements of PEFR on waking, prior to taking a bronchodilator medication and before bed after a bronchodilator, are very useful in demonstrating the variable airflow limitations characterizing asthma.
It's also useful in the longer-term evaluation of the sufferer's disease and its response to proffered treatment. Peak flows should always be measured over several days and preferably over a weekend or short holiday if the effect of the asthma sufferer's work exposure is also being studied.
Exercise tests
These are widely used in the diagnosis of asthma in children. Ideally, the child should run for 6 minutes on a treadmill at a workload which is sufficient to increase their heart rate above 160 beats per minute. Alternative methods use cold air challenge.
Histamine
This test indicates the presence of airway hyper responsiveness, which is a feature found in most asthmatics. It can be predominantly useful in investigating those people whose main symptom is a cough.
Trial of corticosteroids
All asthma sufferers presenting with a severe airflow restriction should undergo formal trials of steroids. Prednisolone 30 mg orally is usually given daily for 2 weeks with their lung function measured before and immediately after the course.
A significant improvement confirms the benefits of this type of treatment for the asthma sufferer. If the trial is for 2 weeks or less, the oral steroids can be withdrawn without tailing off the dose, and should be replaced by inhaled corticosteroids in those people who have responded and are thought will benefit from this medication.
Blood and sputum tests
Individuals with asthma often have an increase in the number of eosinophils in peripheral blood. However the presence of large numbers of eosinophils in the sputum is a more useful diagnostic tool.
Chest X-ray
This has a slightly limited use as there are no diagnostic features of asthma on a chest X-ray, although during an acute occurrence or in chronic severe disease over inflation is a characteristic often found in a chest x-ray.
Skin tests
Skin-prick tests should be performed in all cases of asthma to help identify allergic triggers.
Asthma Treatment
Although there is no cure for asthma, effective management is available for preventing attacks and controlling and ending attacks soon after they have begun.
Asthma medications are taken orally or inhaled in vapour form using a metered-dose inhaler. This is a hand-held pump which delivers medicine directly to a person's airways.
There are two kinds of asthma medication: bronchodilators, which reduce broncho-spasms; and anti-inflammatory medications, which reduce airway inflammation.
Immunotherapy is another treatment option for asthma caused by allergens. This form of therapy modifies a person’s allergic response by repeated exposure to small amounts of allergens.
By breathing into a PEFR, a small hand-held device called a flow meter, an asthmatic can find out when their airways are first starting to narrow. When the PEFR falls, asthma medication is probably needed to prevent an attack.
Note:
PEFR and medication should only ever be used under a physician’s guidance.
There are two basic kinds of medication for the treatment of asthma:
Long-term control medications – These are used on a regular basis to prevent attacks and not to be used for treatment during an attack.
These include:-
o inhaled steroids (e.g., Azmacort, Vanceril, AeroBid, Flovent) prevent inflammation
o leukotriene inhibitors (e.g., Singulair, Accolate)
o long-acting bronchodilators (e.g., famoterol, Serevent) help open airways
o cromolyn sodium (Intal) or nedocromil sodium
o aminophylline or theophylline (This isn't used as frequently as it was in the past)
o a combination of anti-inflammatory and bronchodilators, using either separate inhalers or a single inhaler (Advair Diskus)
Quick relief (rescue) medications – which are used to relieve the symptoms during an acute attack.
o short-acting bronchodilators (e.g., Proventil, Ventolin, Xopenex, and others)
o oral or intravenous corticosteroids (e.g., prednisone, methylprednisolone) which help to stabilize severe episodes of asthma.
People with mild asthma (infrequent attacks) can use their relief medication as needed, but those with persistent asthma problems should take their control medications on a regular basis to prevent their symptoms from occurring.
A severe asthma attack requires a medical evaluation and may even require hospitalization with oxygen, intravenous therapy and medications being required.
How to Approach Asthma Management
A winning approach to asthma management is critically dependent on using the correct anti-inflammatory medications with broncho-dilators which are needed for immediate and occasional relief of symptoms of asthma.
- Anti-Inflammatory - Preventers: Anti-inflammatory medication is used to treat the inflammation caused by exposure to inducers.
2. Bronchodilators - Relievers (Rescue medication)
Bronchodilators are used to relieve Broncho-constriction which is provoked by triggers.
Medications: Anti-inflammatory
A successful move towards decent asthma management, both in and out of an acute hospital setting is dependent upon the accurate use of anti-inflammatory treatment and bronchodilators being prescribed for immediate and occasional relief of any symptoms shown.
Anti-inflammatory medications work mostly by interfering with the activity and chemistry of immune cells, such as mast cells, which cause inflammation in the airway walls. Anti-inflammatory medication also helps rest the airway muscles that narrow and constrict during broncho-spasms.
Anti-Inflammatory Medications (Preventers)
These:-
· prevent and reduce inflammation, swelling and mucus in the airways
· put a stop to symptoms such as cough, wheeze and breathlessness
· need to be taken on a regular basis
· are slow acting (over hours or weeks)
Types of Anti-Inflammatory Drugs
There are steroidal and non-steroidal anti-inflammatory drugs.
The most common ones include:
A-Steroids
- beclomethasone (Beclovent®, Vanceril®, Becloforte®)
- budesonide (Pulmicort®)
- flunisolide (Bronalide®)
- fluticasone (Flovent®)
B-Non-Steroidal
- sodium cromoglycate (Intal®)
- nedocromil (Tilade®)
Corticosteroid Inhalers
Corticosteroid drugs are the most effective Preventers. They work by reducing and preventing airway inflammation, swelling and mucus. They must be used regularly and do not have an instant effect. This means they have no value whatsoever if an effect is needed straight away.
The Side effects of Corticosteroid Inhalers
There are few side effects at low doses
- High doses might cause growth suppression; studies have shown children whose asthma is not controlled don't grow as quickly as other children.
- side effects, in general, are usually restricted to the throat:
- hoarseness and sore throat
- Thrush or yeast contamination which can be prevented by rinsing the mouth and gargling, Using a holding chamber can also help prevent side effects.
Corticosteroid Tablets
Corticosteroid tablets or Prednisone®:
- These are used when inflammation becomes severe
- They reduce inflammation, swelling & mucus, and help bronchodilators work better
- They start to work within a few hours, but may take several days to have a full effect
- They are often used for short periods of time just to get the inflammation under control
- There are lots of side effects if used on a long-term basis such as water retention, bruising, puffy face, increased appetite, weight gain and stomach irritation.
Other Preventers
Other preventers are Intal® and Tilade®. They are non-steroidal and again used to reduce inflammation.