Conditions, types, triggers, & treatments
Asthma is a chronic inflammatory disease of the airways in the lungs in which there is narrowing and swelling of the airways and production of excess mucus. It is marked by spasms of the airways, or bronchial tubes, as well as shortness of breath, coughing, wheezing (a whistling sound when you breathe) and chest tightness or pain. It can affect people of all ages, but it often starts during childhood.
Asthma is triggered by hypersensitivity of the airways to inhaled stimuli, such as:
- Pet dander (skin flakes, fur or feathers shed by animals)
- Dust mites,
- Chemical fumes,
- Strong odours or air pollution.
Asthma can also be triggered by the following causes:
- Medications (i.e. aspirin and acetaminophen),
- High stress,
- Extreme weather conditions or
- Respiratory illness or the flu.
Thunderstorm asthma is a form of asthma-related to triggers from an uncommon combination of high pollen or dust (usually occurs during late Spring to early Summer) and a certain type of thunderstorm.
Flare-ups can vary in severity and may also be life-threatening. A major Thunderstorm event happened in late 2016 in Melbourne where they had a number of deaths and a massive influx of people being hospitalised.
The pollen and/or dust are drawn up into the clouds as they formed and carried in the clouds until the rain starts to fall, the moisture in the cloud breaks up the pollen, and the winds which are generated from the temperature difference from the rain carry the fine particles of pollen and dust.
The moisture in the clouds breaks down the particles to a size which is below 500 to 600 micros which makes means that fewer particles are captured by the hairs and mucus, which is the body’s natural filtering, collection and removal system. The finer pollen and dust particles become more concentrated, and they pass into the airway walls easier than normal, causing the walls of the airways to become inflamed easier and in a more severe way.
These finer particles can also affect people who have hay fever and even people who have unrecognised asthma who would not normally be affected by triggers as their mucociliary escalator would normally capture these particles and remove them effectively without major inflammation occurring in the airways.
The mucociliary escalator filters particles which are larger than approximately 500-600 microns, these particles are then moved up and out of the lungs and into the throat to be swallowed and coughed out naturally.
When particles are below 500-600 microns, they pass through the mucus and go directly into the airways, this directly affects the inflammatory cells of airways, causing a flare-up (please read “What Happens During an Asthma Flare-Up? below”).
Different Types of Asthma
- Childhood Asthma
- Atopic or childhood asthma is the most common disease
- in childhood and is strongly genetic in origin. Symptoms, together with allergic rhinitis and atopic dermatitis (eczema), often occur with identifiable triggers.
- Allergic Asthma
- This is the most common type of asthma and is triggered by inhaled allergens. About 90% of kids with childhood asthma have allergies, compared with about 50% of adults.
- Exercise-induced asthma (EIA) or exercise-induced bronchoconstriction (EIB)– Physical exertion triggers asthma symptoms. Quick breathing of air drier than the air inside the body during exercise causes loss of heat and/or water from the lungs and dehydration of bronchial tubes, which results in narrowing of the airways.
- People with this condition often work around chemical fumes, dust or other irritants in the air. Occupational factors are associated with up to 15 per cent of disabling asthma cases
Diagnosis of Asthma
An allergist has specialised training and experience in the treatment and diagnosis of asthma and allergies. An allergist obtains thorough patient and medical history and performs breathing tests, such as spirometry. Many people with asthma also have allergies, so an allergist may perform skin testing to assess sensitivity to allergens. X-rays and blood tests may also be performed.
Symptoms of Asthma
The common symptoms include:
- Wheezing (a whistling or squeaky sound in your chest when breathing, especially when exhaling)
- Chronic coughing
- Chest tightness or pain
- Shortness of breath
Symptoms often occur at night, early in the morning or during/after activity or exercise.
Ongoing health problems like obesity, obstructive sleep apnea, acid reflux and depression can cause symptoms to worsen.
If you experience symptoms on a regular basis, you should see your doctor.
Treatment and Management of Asthma
There is no cure for asthma but its symptoms can be controlled with effective treatment and management. This involves avoiding triggers that cause the asthma symptoms and taking asthma medications as directed.
Avoid triggers and stay healthy
According to Mayo Clinic (www.mayoclinic.org), avoiding exposure to triggers and staying healthy are key aspects of asthma control. These lifestyle and home remedies include the following:
- Use air conditioner. Air conditioning lowers indoor humidity and reduces that amount of airborne pollen and dust mites indoor.
- Decontaminate your decor. Minimise dust by replacing certain items in your house, i.e. removing carpet and installing hardwood or linoleum flooring, using washable curtains and blinds and using dustproof pillow covers and mattresses.
- Use dehumidifier to maintain optimal humidity.
- Prevent mold spores. Clean damp areas in house like the bath and kitchen to keep molds from developing. Get rid of moldy leaves or damp firewood in the yard.
- Reduce pet dander (skin flakes, fur or feathers shed by animals). Avoid pets with fur or feathers. Having regularly bathed and groomed pets may reduce the amount of dander in your surroundings.
- Clean regularly. Clean your home at least once a week. Wear a mask when cleaning or have someone else do it.
- Cover your nose and mouth if it is cold. Wearing a face mask can help if your asthma is triggered by cold or dry air.
- Get regular exercise. Regular exercise can strengthen your heart and lungs, which help relieve asthma symptoms. This is because exercise assists in the mucus clearance and removal process by creating a wind shearing process when you exert yourself, helping to take the top layers of the mucus with it and helping to push the mucus up and out of your lungs and into your throat to be swallowed or coughed out.
- Maintain a healthy weight. Being overweight can worsen symptoms.
- Control heartburn and gastroesophageal reflux disease (GERD). It is possible that acid reflux can damage the airways and worsen symptoms. You may need treatment of GERD before asthma symptoms improve.
The following are important pathophysiological features of asthma:
Airway hyperresponsiveness (AHR) – AHR is the defining characteristic of asthma wherein there is exaggerated airway narrowing due to an increased sensitivity of the airways to stimuli.
There are two types of Airway Hyperresponsiveness (AHR): Acute and chronic AHR, based partly on its response to inhaled corticosteroids (ICS).
The acute AHR is thought to be due to acute inflammatory changes, such as mucus hypersecretion, airway wall edema and plasma leakage, and it responds well to ICS.
The chronic AHR, on the other hand, is primarily due to airway wall remodelling, such as fibrosis, smooth muscle hyperplasia/hypertrophy and airway nerve hyperalgesia, and it does not respond well to anti-asthma therapy when administered for several years. AHR invariably correlates with the disease severity and its measurements are useful in making a diagnosis of asthma.
What Happens During an Asthma Flare-Up?
An asthma flare-up is caused by three important changes in the airways that make breathing more difficult:
- Airway Inflammation – Exposure to asthma triggers not only increase airway responsiveness, but inflammation of the airways as well. In asthma, the inflammatory response is activated inappropriately and is harmful rather than beneficial. The mechanisms involved in the persistence of inflammation in asthma remain poorly understood. The combination of the chronic inflammation and transient acute inflammatory episodes correspond to exacerbation of asthma.
- Excess mucus -This results in congestion and mucus “plugs” that get caught in the narrowed airways. Mucus Plugs may lead to the reduction in the lung capacity as they reduce or shut off access for oxygen to reach the Alveoli and Carbon Dioxide to exit the airways at the end of these closed or semi-closed airways and reducing the surface area of the blood vessels to perform gas exchange of Oxygen and Carbon Dioxide.
- Narrowed airways or bronchoconstriction – Bands of muscle lining the airways tighten up, further narrowing and constricting the airways, creating an obstruction and making it harder to breath.
These 3 changes can also lead to a condition called Gas Trapping where Carbon Dioxide is trapped between the mucus plug and the Alveoli, where it is unable to escape from the lungs.
The exact role of many different inflammatory cells involved in asthma is not yet certain, but some cell types predominate.
- Mast cells are increased in airway smooth muscles in patients with asthma and these cells initiate the acute Bronchoconstrictor responses to triggers.
- Macrophages are derived from blood monocytes and may accumulate in the airways and may be activated by allergens to initiate inflammatory response.
- Dendritic cells play a critical role in the allergen-induced responses in asthma.
- Eosinophil infiltration is a characteristic feature of allergic inflammation and there is a correlation between increased eosinophil counts in peripheral blood or bronchial lavage (BAL) and AHR.
- Neutrophils in the airways is predominantly observed in severe asthma and also in patients who die suddenly of asthma.
- T-lymphocytes play an important role in coordinating the inflammatory response in asthma through recruitment of eosinophils and maintenance of mast cells in the airways.
- Platelet activation may be observed and there is evidence of platelets in bronchial biopsies of patients with asthma.
- Airway remodeling – There are structural irreversible changes that occur in the airways of patients with asthma. These changes are characterised by:
- Airway epithelial shredding – The disruption of epithelium or outer layer of the airways is a characteristic feature of asthma and may contribute to AHR and chronic inflammation in several ways, including penetration of allergens due to loss of outer lining barrier, increased neural reflexes due to exposed sensory nerves, loss of anti-inflammatory enzymes and epithelium-derived relaxant factor, and release of mediators resulting in an increased inflammatory response. Epithelial cells may release growth factors that stimulate structural changes in the airways as an attempt to repair the damage caused by chronic inflammation.
- Fibrosis – The subepithelial cells (beneath outer cellular covering of internal and external surfaces of the airways) appear thickened in patients with asthma, which may lead to irreversible loss of lung function.
- Airway smooth muscle hypertrophy and hyperplasia –Both airway smooth muscle hyperplasia (an increase in the number of airway smooth muscle cells) and hypertrophy (an increase in the size of airway smooth muscle cells) have been shown in the airways of patients with asthma, and these are thought to be due to inflammatory mediators, growth factors, cytokines, extracellular matrix proteins, and genetic factors.
Pharmacologic management of asthma
- Long-term prevention medications are generally taken daily and include inhaled corticosteroids (fluticasone, budesonide, flunisolide, ciclesonide, beclomethasone, mometasone and fluticasone furoate), leukotriene modifiers and combination inhalers containing an inhaled corticosteroid and long-acting beta-agonist (LABA). LABA helps open the airways but may carry some risks. It should never be prescribed as the sole therapy, but should always be used in combination with inhaled corticosteroids. Theophylline keeps the airway open but is not used as often as in past years.
- Short-acting beta-agonists, ipratropium (Atrovent) and oral and intravenous corticosteroids are used as quick-relief or rescue medications to quickly relax and open the airways and relieve symptoms during an asthma flare-up. This medication may also be taken before exercising if recommended by a doctor. Quick-relief or rescue medications do not take the place of controller medications. A quick-relief or rescue inhaler can ease an asthma flare-up right away, but should not be used very often if the long-term controller medications are working properly. If you need to use your quick-relief inhaler frequently, it is recommended that you see your doctor to adjust your long-term controller medication.
- Allergy medications, such as allergy shots (immunotherapy) and omalizumab (Xolair), may help if asthma is triggered or worsened by allergies.
- It is important for people with asthma to get vaccinated annually as they are at risk of developing complications from respiratory infections, such as influenza (flu) and pneumonia.
Management of Productive Cough
Oscillating Positive Expiratory Pressure therapy has been proven effective in assisting patients with asthma in the following three processes:
1. Positive Expiratory Pressure (PEP)
The ball bearings create a seal with the cone so that when you blow into the device, this creates a positive pressure going back into your lungs and airways called Positive Expiratory Pressure (PEP). This positive pressure expands your lungs and airways (similar to how a balloon expands when you blow into it). By inflating your airways, this helps to loosen any closed or semi-closed airways from mucus plugging and loosen any obstructions or blockages in the airways which restrict your ability to breathe.
2. Air Pressure Release
When the pressure in the device reaches a specific level, the ball bearing lifts off the cone, breaking the seal and allowing the air to rush out of the devices. This air release also allows the air to release from the lungs and airways, up and out of the lungs and throat, creating a gentle suction effect as it rushes out.
This assists the body’s natural cleaning method called the mucociliary escalator (cilia/hairs on the airway walls) by pulling the mucus as it rushes past, helping to remove the built-up mucus with the trapped foreign particles (smoke, pollution, pollen, etc..) and bacteria up and out of the lungs and into the throat to be coughed out naturally.
Process 1 and 2 occur between 25-35 times per second, causing the airway walls to open and close continuously over a period of 2-3 seconds. The causes the airway walls to shake, loosening the mucus bond to the airways, helping to mobilising the mucus for better expulsion out of the body.
The combined action of oscillation and positive expiratory pressure therapy assists the body’s natural mucus clearance process, helping to clean out any foreign particles. This includes triggers, which may have inflamed the airways and encouraged hyper-secretion (excess mucus), the excess mucus may then capture bacteria and viruses to be trapped in the mucus, which may lead to a cold or flu.
The device also helps to improve breathing by opening up the airways and expanding the lungs.
Management of exercise-induced asthma (EIA) and occupational asthma
The prevention and treatment of occupational asthma require environmental interventions, including education on behavioural changes to avoid triggers, along with drug therapies and careful medical follow-up.
Management of exercise-induced asthma (EIA) involves:
- Warming up with gentle exercises for about 15 minutes
- before starting more intense physical activity,
- Using a scarf or face mask to cover mouth and nose when exercising in cold weather,
- Trying to breathe through the nose while exercising, which helps warm the air that goes into the lungs, as well as using the hairs in the nose which act as the body’s natural air filter
Lastly, work with your doctor to create an asthma action plan, which may include:
- A list of your regular medications and how many times each day you should take them.
- A list of triggers and how to avoid them.
- How to tell if your condition is getting worse or an attack is developing and how to manage it.
- Symptoms that are serious enough to need urgent medical help.