Asthma

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Definition & Description

Asthma is a chronic lung disease which is a very common respiratory condition. It is also known as a reactive airway disease which is inconvenient most of the time but manageable. Asthma is caused by inflammation and constriction of bronchial walls which leads to a series of spasmodic attacks of wheezing and shortness of breath as a result of the hyper-reactivity of smooth muscle in the bronchial walls and in the absence of any other apparent cause. There are various factors such as exposure to cigarette smoke, climate change, physical exertion or emotional stress that causes asthma. It begins during childhood and the disease is commonly triggered by viral infection.

Asthma can be diagnosed by the presence of the signs and symptoms. The diagnosis is normally confirmed by presenting a response to a inhaled bronchodialator. Often pulmonary function tests, chest x-rays and blood tests can also be done in order to confirm the diagnosis.

The first symptoms in children may appear before the ages of five years. However, diagnosing asthma in young children age 0-5 is difficult due to the fact that other childhood conditions may have similar symptoms. Since it is harder to diagnose asthma in a children younger than 5 years, the doctor, must rely on the children's medical history, the symptoms and physical exams to make a diagnosis, or the doctor could run a 4-6 week asthma medication trial to see how well the child responds(US department of health and human services 2009).

Pathology

In asthma constriction of the airwaves is caused by bronchial constriction and bronchial inflammation. Bronchial constriction and inflammation results in a chronic disorder of the lungs in which airways are prone to be narrowed, causing episodes of wheezing, chest tightness, coughing and breathlessness that range in severity from mild to potentially life threatening 

Allergens enters the airway this results in swelling of the highly sensitive airway. This results in constriction of the muscles around the airway and the excessive release of mucs in the area resulting in a narrowing of the airway which in turn causes a decrease in the amount of air flowing into and out of the lungs . Due to the decrease in the flow of air in and out of the lungs, the lungs become hyperinflated. When the tidal volume reaches a capacity similar to the pulmonary dead space there is hypoventilation of the alveolar. This results in a ventilation-perfusion mismatch which is worsened by vasoconstriction 

When hypoxia results from the ventilation perfusion mismatch, the diffusion of carbon dioxide across the alveolar capillary membranes prevents hypercarbia from taking place during the early stages of an acute attack. Therefore patients with an acute episode in the early stages have hypoxia with the absence of retention of carbon dioxide. A decrease in PaCO2 also occurs because of the hypoxia that triggers hyperventilation. The increase of alveolar ventilation during early stages of an acute exacerbation prevents hypercarbia from occurring. Due to worsening obstruction and an increase in ventilation-perfusion mismatch, CO2 retention results. Hyperventilation results in respiratory alkalosis during the first stages of an episode. Metabolic acidosis results later on, when there is an increase of oxygen consumption, work of breathing and cardiac output. Respiratory failure causes respiratory acidosis.

There is an association of Chronic inflammation of the airways with an increased heart rate, therefore leading to bronchospasms, wheezing, shortness of breath, coughing due to exposure to allergens, environmental irritants, exercise, cold air or viruses. For some patients that has chronic asthma, limitation of airflow may be only partially reversible due to airway remodeling (hyperplasia and hypertrophy of smooth muscle, angiogenesis, and subepithelial fibrosis) that happens with chronic untreated disease.

Types of Asthma

• Allergic asthma:
  • The type of asthma that is triggered by allergies(substance that is responsible to cause allergic reaction more especially in sensitive people)

• Intrinsic asthma:
  • Usually develops after the age of 30 years where allergies do not play any role. It is likely triggered by respiratory irritation substances (e.g cleaning agents, perfume and smoking).

• Exercise Induced Asthma:
  • It affects anyone and at any age. It is caused by lack of heat and moisture in the lungs which occurs during strenuous exercises.

• Nocturnal Asthma:
  • Is the type of asthma that attacks people when they are asleep. The victims tend to sleep earlier and they wake up in the middle of the night (1-4am) due to difficulties with breathing and they will drink a glass of water to try to relieve the symptoms. 

• Occupational Asthma:
  • Occurs as the result of inhaling chemical fumes or dust on the working environment (X-Plain.com).

• Steroids Resistance Asthma:
  • Overuse of asthma medications which leads to status asthmatic and severe asthma that does not respond with any medication.
    

Signs and Symptoms

Since there is narrowing of the bronchial airways, the following signs and symptoms may arise:

• Wheezing(especially present during attack)
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• Chest tightness(especially present during attack)
• Shortness of breath(especially present during attack)
• Tiredness(specially during strenuous exercise)
• Itchy throat(that may be triggered and worsened by dust particles, perfume or smoke)
• Continuous coughing which is usually worse early in the morning or at night (especially present during attack)
• Headache
• Constant blocked-runny nose
• Changes in amount,thickness and color of sputum

When does asthma become life threatening?

• Difficulty to catch a breath
• Difficulty talking and concentrating
• Difficulty talking and walking
• Cyanosis of skin especially around the mouth and finger areas
• Nasal flaring and constant wheeze

When these signs and symptoms presents, a person should be aware and are advice to consult with your general practitioner as soon as possible.

Prevalence and Mortality

File:Asthma world map.png

WHO Asthma World Map

Asthma affects approximately 1 in every 10 children and 1 in every 20 adults. It usually starts before the age of 5, however it can occur for the first time at any age, even in adulthood. If it occurs in adulthood for the first time it will usually persist, but a child can outgrow it in their teenage years. (Jeena,P., Luyt,D., & Morris,A. 2004). In South Africa, particularly Durban and Soweto, there has been and increase in hospital admissions over the past 25 years. A 25 to 200 times increase has been recorded. (Jeena, P. et al. 2004)

The mortality rate for South Africa was estimated to be 77.643 deaths per one million people. It has the second largest mortality rate in the world after South Korea with 86.9226 deaths per one million people, followed by Georgia with an estimation of 59.226 deaths per one million people after South Africa.

Risk Factors and Prevention

There are a few risk factors associated with asthma that can lead to the onset of asthma, an attack or other respiratory symptoms

• the closeness of home or work to airports, industries and shopping centers(environmental irritants)
• the dampness level of home or work
• being a smoker, living with a smoker or working with a smoker
• the use of spray insecticides or insect oils
• having pets at home, allergies and sinusitis
• having mats or carpets that can easily trap dust particles
• insufficient education and information

Prevention of an attack or an episode is better in the case of asthma because it cannot be cured

• education on the disease and medication that is used
• follow the doctor's instructions on how to use medicine and how to keep symptoms under control
• identify the aggravating factors e.g. smoke, dust, etc.
• keep record of recurrent symptoms and try and maintain control
• go to doctor for regular checkups
  

Many substances can trigger allergies and the same applies to asthma. Common allergens that triggers asthma are pollen, mold, dust mites and pet dander. Other irritants are smoke, pollution fumes, sprays and cleaning chemicals. Asthma symptoms can therefore be reduced by avoiding exposure to known respiratory irritants and allergens.

Medical Management

Various medication exists that help the control of asthma by reducing inflammation of the airway and bronchial constriction, these medications are administered orally, via aerosol or an inhaler. (Cleveland Clinic. 2009)

One form of an inhaler is a bronchodilator, which allows dilatation of the bronchioles and in turn relieves some of the symptoms. It also aids in mucus removal from lungs. There are two forms of bronchodilators:

1. Short-acting beta 2-agonists (quick acting or rescue medicine): these drugs are used best to treat sudden and severe or new asthma symptoms as they open the airways and relieve symptoms within 20 minutes and lasts four to six hours. It can also be used before physical activity about 15-20 minutes before the time to prevent exercise-induced asthma.
2. Long-acting beta 2-agonists: these drugs are not used to for a quick relief of asthma symptoms, instead they are used to control symptoms and their effect lasts 12 hours.
   

Physiotherapy Management

Evidence is weaker concerning the benefits of asthmatic physiotherapeutic treatment/management for asthmatic patients. It only shows that the primary categories of asthma breathing exercises that could benefit asthmatic victims. It involves training the respiratory muscles to increase their strength and endurance .

The aim of breathing pattern retraining is to develop a more efficient pattern of respiration, thereby reducing breathlessness. This is usually accomplished by slowing the breathing rate, and encouraging relaxed, ‘abdominal’ breathing (Bruton, 2006). Another potential mechanism for breathing pattern retraining is that by encouraging a longer expiratory time, the effects of any static/ dynamic hyperinflation may be reduced. The principles of overload and specificity can be applied to the respiratory muscles to produce adaptations that will improve strength and endurance, like any other skeletal muscles. The controversy rests on whether this is of any clinical or functional value to patients. Specific training usually involves breathing at increased levels of ventilation or against external mechanical loads (Bruton, 2006).
The following physiotherapy management techniques would also be beneficial:

• Removal of secretions: due to the allergen excessive mucous is produced in the lungs, physiotherapy techniques such as percussions/shaking/vibrations, postural drainage and effective coughing are used to manage the removal of these secretions and prevent infection from occurring.
• Posture: physiotherapist educate the patient on the correct posture in standing, sitting, etc which assists in the management of asthma attacks by allowing the chest to expand appropriately and the lungs to function optimally
• Range of motion exercises for patients who need hospitalization.
• Exercise tolerance: physiotherapy aims at improving exercise tolerance in order to reduce breathlessness when the patient is performing any activity. (Porter, S & Tidy, N. M., 2008)
• Education: To the patients and their families on use of a bronchodilator and any other medication, and about condition and lastly how to prevent any chest infection from occurring by advising them on various areas, and so, to avoid.
  

Unfortunately there is no cure for this illness but there are ways of effectively managing the disease. However this should involve the active participation of both the person suffering from the disease and his/her doctor.

Recent Related Research (from Pubmed)

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References

• Bass, P. (2009). What is asthma?. About.com: The New York Times Company. Retrieved from http://asthma.about.com/od/asthmabasics/a/Asthma_whatis.htm
  

• Bruton, A., Garrod R. (2006). Physiotherapy practice and asthma. Editorial or Opinion Piece. Retrieved on April,3, 2009, from: http://www.library.nhs.uk/respiratory/ViewResource.aspx?resID=124901
  

• Cleveland Clinic. (2009). Treating Asthma with bronchodilators. Retrieved on February,17, 2009, from http://my.clevelandclinic.org/disorders/Asthma/hic_Treating_Asthma_With_Bronchodilators.aspx.

• Jeena,P., Luyt, D., Morris,A. (2004). What is Asthma? Department of Health. Retrieved on April,11, 2009, from http://www.capegateway.gov.za/eng/pubs/public_info/W/67819

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• National Institute of Health. (2009). What is Asthma?. United States Department of health and human resources. Retrieved from http://www.nhlbi.nih.gov/health/dci/Diseases/Asthma/Asthma_WhatIs.html

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• Shellharbour Hospital. (2004). Nurse Practitioner Clinical Practice Guidelines for the Management of Asthma in Children. Retreived from http://www.health.nsw.gov.au/resources/nursing/practitioner/pdf/kd_paed_guidelines_asthma.pdf