What Is Asthma?
Air moves into and out of the lungs by traveling along airways. Asthma is a chronic medical condition that affects these airways, and that in affecting the airways, can make it difficult for asthma sufferers to breath. The airways that move air into and out of the lungs are surrounded by muscles. Asthma attacks are characterized by spasming of these muscles. When the muscles that surround the airways spasm, they squeeze the airways and make them more narrow. Narrow airways are able to move less air into and out of the lungs. In addition to the airways being narrow due to the spasming of the muscles that surround them, asthma attacks are also frequently characterized both by inflammation of the airways and by increased mucus production from the airways.
Inflammation of the airways further narrows them while increased mucus production from the airways frequently creates obstructing “mucus plugs”. Ultimately, when the airways first becoming narrowed by spasm and then become inflamed and plugged with mucus, they are not able to move as much air into and out of the lungs. With less air moving into and out of the lungs, asthma sufferers may feel short of breath during an asthma attack.
What Are Possible Risk Factors for Developing Asthma?
- Family history of asthma.
- Being overweight.
- Being a smoker or being exposed to secondhand smoke.
- Having an allergic condition like Hay Fever or Atopic Dermatitis/Eczema.
- Being born prematurely, though research has shown that children who develop asthma due to premature birth frequently outgrow it.
- Not having been breastfed as an infant.
What Are Common Triggers For An Asthma Attack?
- Outdoor allergens like pollen
- Indoor allergens like dust, pet dander and mold
- Cigarette smoke
- Emotional stress
- Cold air
- Thunderstorms/rainy weather
- Dairy products
- Certain medications (including NSAID pain medications like Motrin and Beta-Blockers that are frequently used to treat high blood pressure)
- Cockroach droppings
- Bacterial or viral respiratory infections
- Heartburn/Acid Reflux
What Happens During An Asthma Attack?
Asthma attacks typically occur after a person with asthma has been exposed to one of the asthma triggers listed above. After exposure to an asthma trigger has occurred, the airways of an asthmatic become “irritated” by that trigger. Once airways have become irritated, three things can occur. Firstly, the muscles that surround the airways can spasm. This spasming can cause narrowing of the airways. Secondly, the airways can become inflamed. This inflammation can further narrow the already narrowed airways. Thirdly, the airways can begin to produce too much mucus. The airways produce this mucus in an effort to “wash” away whatever trigger it was that initially irritated the airways leading to the asthma attack. Unfortunately, this build up of airway mucus can lead to the formation of mucus plugs. These mucus plugs can further prevent good airflow through the already narrow and inflamed airways. With airflow through the airways compromised, feelings of shortness of breath can occur.
What Are Common Symptoms of Asthma?
- Persistent cough
- Shortness of breath
- A sensation of chest tightness
- Wheezing (which sounds like a whistling while breathing, especially when exhaling).
Why Is Asthma Dangerous?
The human body needs oxygen to survive. Asthma however can severely limit how much oxygen carrying air is delivered to the lungs. This can in turn limit how much oxygen is available for use by the human body. Limited oxygen availability can cause both short term and long term damage to many of the body’s most critical organs.
How Is Asthma Diagnosed?
Asthma is most commonly diagnosed using Pulmonary Function Tests (PFT’s). PFT’s assess how well a person is able to move air into and out of their lungs. The most common PFT’s are Spirometry, the Exhaled Nitric Oxide test and Challenge Tests.
Spirometry is a simple test that measures how well someone is able to blow air out of their lungs. To perform spirometry, a person simply is asked to blow as hard as possible into a tube. The force with which they are able to blow air into the tube is measured. Many times during spirometry testing, a person may be asked to perform the spirometry test before and then again after taking a “bronchodilator” medication. Bronchodilators are medications that can widen narrowed airways. If a marked improvement in the ability to blow air out of the lungs is seen after taking a bronchodilator, this is frequently consistent with a diagnosis of asthma.
Exhaled Nitric Oxide
Asthma is a condition that is characterized by inflammation and spasming of the airways. The human body produces a gas called Nitric oxide when inflammation is occurring. So, the Exhaled Nitric Oxide test just involves a person breathing into a small, handheld machine for about 10 seconds. The machine then calculates the amount of nitric oxide present in the air that the person breathes out. If there is more Nitric Oxide than is normally contained in human breath, this indicates that there is airway inflammation present. Airway inflammation is a frequent indication that asthma is present.
When a diagnosis of asthma is still not clear after Spirometry and/or Exhaled Nitric Oxide testing, a Challenge Test may then be performed to confirm the diagnosis. There are 2 types of challenge tests. There is the Methacholine Challenge Test and there is the Mannitol Challenge Test. Methacholine and Mannitol are both inhaled agents that cause the airways of people with asthma to spasm. During these tests, a person inhales increasing amounts of either a Methacholine aerosol mist or a Mannitol dry powder before and again after a spirometry test. The Challenge Test is deemed to be “positive” when a person’s lung function decreases after he or she has inhaled the Methacholine or the Mannitol. After the test has been completed, a bronchodilator medication is then administered to reverse the effects of the Methacholine or the Mannitol on the airways.
How Is Asthma Treated?
There are two basic approaches taken to the treatment of asthma. The first approach involves preventing asthma attacks. This is done by either avoiding exposure to asthma triggers or by using long-term asthma “control medications”. The second approach involves using asthma “rescue medications”. These medications are meant to acutely treat an asthma attack when it is occurring. Rescue medications can “rescue” an asthma sufferer when they are having an asthma attack, but they won’t necessarily prevent an asthma attack. Control medications can “control” asthma by preventing an asthma attack, but if an asthma attack occurs, control medications won’t resolve it.
Asthma Control Medications
- Corticosteroids – Corticosteroids are medications that can prevent inflammation. A great deal of what happens during asthma attacks and exacerbations involves airway inflammation. Taking corticosteroids can prevent this airway inflammation, making an asthma attack or an asthma exacerbations less likely. Corticosteroids can be taken in the form of a pill (i.e. Prednisone). Corticosteroids can also be inhaled and delivered directly into the lungs (i.e. Pulmicort, Symbicort, Qvar).
- Inhaled Long-Acting Beta Agonists – Inhaled Long-Acting Beta Agonists cause the muscles that surround the airways to relax. A great deal of what happens during asthma attacks and asthma exacerbations involves the muscles around the airways spasming. Inhaled Long-Acting Beta Agonists can help to prevent this spasming. A commonly prescribed Inhaled Long-Acting Beta Agonists is Serevent.
- Combined Corticosteroid/Inhaled Long-Acting Beta Agonists – The two primary processes that lead to asthma attacks and/or exacerbations are airway spasming and airway inflammation. Combined Corticosteroid/Inhaled Long-Acting Beta Agonists can prevent asthma attacks and exacerbations by preventing both airway spasms and airway inflammation. Commonly prescribed combined Corticosteroids/Inhaled Long-Acting Beta Agonists include Advair, Symbicort and Dulera.
- Omalizumab – Many asthmatics suffer asthma attacks after their airway’s have been irritated by certain allergens. Exposure to these allergens causes the body to release Immunoglobulin E (IgE). IgE is an antibody that normally helps the body to fight against allergens. IgE however can also cause spasming of the muscles around the airways, ,leading to an asthma attack. Omalizumab works to prevent asthma attacks by blocking the spasming effect of IgE on the muscles that surround the airways.
- Leukotriene Modifiers – Leukotriene Modifiers work by preventing inflammation of the airways. Commonly prescribed Leukotriene Modifiers include Singulair, Zyflo and Accolate.
- Cromolyn Sodium – Cromolyn Sodium is an inhaled “Mast Cell Stabilizer”. Mast Cells are cells in the human body that release chemicals called histamines after the body has been exposed to a potential asthma attack inducing allergen. Histamines can cause the muscles that surround the airways to spasm, leading to an asthma attack. By “stabilizing” Mast Cells, Cromolyn Sodium basically prevents them from releasing the histamines that can cause an asthma attack.
- Theophylline – Theophylline is a “methylxanthine” medication. Methylxanthines relax the muscles that surround the airways. By relaxing these muscles, the airway spasming that is characteristic of an asthma attack is prevented.
Asthma Rescue Medications
- Short-Acting Beta Agonists – Short-Acting Beta Agonists are inhaled asthma rescue medications. This means that they are used to immediately “rescue” someone who is having an asthma attack. Short-Acting Beta Agonists rescue an asthma sufferer by quickly relaxing the muscles around the airways that spasm during an asthma attack. Short-Acting Beta Agonists are the first choice for quick relief of asthma symptoms. Commonly prescribed Short-Acting Beta Agonists include ProAir, MaxAir, Proventil and Ventolin.
- Anticholinergics – Anticholinergic medications are asthma rescue medications meant to immediately rescue someone having an asthma attack. While fast acting, anticholinergics are not as fast acting as the Short-Acting Beta Agonists are. Like Short-Acting Beta Agonists though, anticholinergics also work by relaxing the muscles that surround the airways and spasm during an asthma attack. Anticholinergics also reduce airway mucous production, helping to prevent formation of the airway mucus plugs that can also make it harder for people with asthma to breath properly. Commonly prescribed anticholinergics include Spiriva and Atrovent.
- Combination Rescue Medications – Combination Rescue Medications combine both Short-Acting Beta Agonists and Anticholinergics. Commonly prescribed combination rescue medications include Combivent and DuoNeb.