Asthma

What is Asthma?

Asthma is a disease affecting the airways that carry air to and from your lungs. People who suffer from this chronic condition (long-lasting or recurrent) are said to be asthmatic.
 

The inside walls of an asthmatic's airways are swollen or inflamed. This swelling or inflammation makes the airways extremely sensitive to irritations and increases your susceptibility to an allergic reaction.

As inflammation causes the airways to become narrower, less air can pass through them, both to and from the lungs. Symptoms of the narrowing include wheezing (a hissing sound while breathing), chest tightness, breathing problems, and coughing. Asthmatics usually experience these symptoms most frequently during the night and the early morning.

For information on the different causes of asthma (allergy, colds, stress, exercise, etc) please see page 4 (causes of asthma). 
Asthma is Incurable

Asthma is an incurable illness. However, with good treatment and management there is no reason why a person with asthma cannot live a normal and active life.
What is an Asthma Episode / Attack?

An asthma episode, or an asthma attack, is when symptoms are worse than usual. They can come on suddenly and can be mild, moderate or severe. 

What happens during an asthma attack? 

The muscles around your airways tighten up, narrowing the airway.
Less air is able to flow through the airway.
Inflammation of the airways increases, further narrowing the airway.

More mucus is produced in the airways, undermining the flow of air even more.

Asthma Attacks Vary

 In some asthma attacks, the airways are blocked such that oxygen fails to enter the lungs. This also prevents oxygen from entering the blood stream and traveling to the body's vital organs. Asthma attacks of this type can be fatal, and the patient may require urgent hospitalization. 

Asthma attacks can be mild, moderate, severe and very severe. At onset, an asthma attack does allow enough air to get into the lungs, but it does not let the carbon dioxide leave the lungs at a fast enough rate. Carbon dioxide - poisonous if not expelled - can build up in the lungs during a prolonged attack, lowering the amount of oxygen getting into your bloodstream.

See Your Doctor

If you suffer from asthma you should see your doctor. He/she will help you find out what triggers your asthma symptoms and how to avoid them. You will also be prescribed medications which will help you manage your asthma.

With experience you will learn to keep away from things that irritate your airways, know when to take your medication, and better control your asthma. Effective asthma control allows you to take part in normal everyday activities.

Consequences of Not Controlling Your Asthma

If you don't control your asthma you will miss school or work more often and you will be less likely to be able to take part in some activities you enjoy. In the USA and Western Europe, asthma is one of the leading causes of school absenteeism.

Types of Asthma

Child-Onset Asthma
 
Asthma that begins during childhood is called child-onset asthma. This type of asthma happens because a child becomes sensitized to common allergens in the environment - most likely due to genetic reasons. The child is atopic - a genetically determined state of hypersensitivity to environmental allergens.

Allergens are any substances that the body will treat as a foreign body, triggering an immune response. These vary widely between individuals and often include animal proteins, fungi, pollen, house-dust mites and some kind of dust. The airway cells are sensitive to particular materials making an asthmatic response more likely if the child is exposed to a certain amount of an allergen.

Adult-Onset Asthma

This term is used when a person develops asthma after reaching 20 years of age. Adult-onset asthma affects women more than men, and it is also much less common than child-onset asthma.

It can also be triggered by some allergic material or an allergy. It is estimated that up to perhaps 50% of adult-onset asthmas are linked to allergies. However, a substantial proportion of adult-onset asthma does not seem to be triggered by exposure to allergen(s); this is called non-allergic adult-onset asthma. This non-allergic type of adult onset asthma is also known as intrinsic asthma. Exposure to a particle or chemical in certain plastics, metals, medications, or wood dust can also be a cause of adult-onset asthma. 

Exercise-Induced Asthma

If you cough, wheeze or feel out of breath during or after exercise, you could be suffering from exercise-induced asthma. Obviously, your level of fitness is also a factor - a person who is unfit and runs fast for ten minutes is going to be out of breath. However, if your coughing, wheezing or panting does not make sense, this could be an indication of exercise-induced asthma.

As with other types of asthma, a person with exercise-induced asthma will experience difficulty in getting air in and out of the lungs because of inflammation of the bronchial tubes (airways) and extra mucus. 

Some people only experience asthma symptoms during physical exertion. The good news is that with proper treatment, a person who suffers from exercise-induced asthma does not have to limit his/her athletic goals. With proper asthma management, one can exercise as much as desired. Mark Spitz won nine swimming gold medals during the 1972 Olympics and he suffered from exercise-induced asthma. 

Eighty percent of people with other types of asthma may have symptoms during exercise, but many people with exercise-induced asthma never have symptoms while they are not physically exerting themselves.

Cough-Induced Asthma

Cough-induced asthma is one of the most difficult asthmas to diagnose. The doctor has to eliminate other possibilities, such as chronic bronchitis, post nasal drip due to hay fever, or sinus disease. In this case the coughing can occur alone, without other asthma-type symptoms being present. The coughing can happen at any time of day or night. If it happens at night it can disrupt sleep. 

Occupational Asthma

This type of asthma is triggered by something in the patient's place of work. Factors such as chemicals, vapors, gases, smoke, dust, fumes, or other particles can trigger asthma. It can also be caused by a virus (flu), molds, animal products, pollen, humidity and temperature. Another trigger may be stress. Occupational asthma tends to occur soon after the patients starts a new job and disappears not long after leaving that job.

Nocturnal Asthma

Nocturnal asthma occurs between midnight and 8 AM. It is triggered by allergens in the home such as dust and pet dander or is caused by sinus conditions. Nocturnal or nighttime asthma may occur without any daytime symptoms recognized by the patient. The patient may have wheezing or short breath when lying down and may not notice these symptoms until awoken by them in the middle of the night - usually between 2 and 4 AM. 

Nocturnal asthma may occur only once in a while or frequently during the week. Nighttime symptoms may also be a common problem in those with daytime asthma as well. However, when there are no daytime symptoms to suggest asthma is an underlying cause of the nighttime cough, this type of asthma will be more difficult to recognize - usually delaying proper therapy. The causes of this phenomenon are unknown, although many possibilities are under investigation.

Steroid-Resistant Asthma (Severe Asthma)

While the majority of patients respond to regular inhaled glucocorticoid (steroid) therapy, some are steroid resistant. Airway inflammation and immune activation play an important role in chronic asthma. Current guidelines of asthma therapy have therefore focused on the use of anti-inflammatory therapy, particularly inhaled glucocorticoids (GCs). By reducing airway inflammation and immune activation, glucocorticoids are used to treat asthma. However, patients with steroid resistant asthma have higher levels of immune activation in their airways than do patients with steroid sensitive (SS) asthma. 

Furthermore, glucocorticoids do not reduce the eosinophilia (high concentration of eosinophil granulocytes in the blood) or T cell activation found in steroid resistant asthmatics. This persistent immune activation is associated with high levels of the immune system molecules IL-2 (interleukin 2), IL-4 and IL-5 in the airways of these patients.

What Causes Asthma?
 
According to recent estimates, asthma affects 300 million people in the world and more than 22 million in the United States. Although people of all ages suffer from the disease, it most often starts in childhood, currently affecting 6 million children in the US. Asthma kills about 255,000 people worldwide every year.
Children at Risk

Asthma is the most common chronic disease among children - especially children who have low birth weight, are exposed to tobacco smoke, are black, and are raised in a low-income environment. Most children first present symptoms around 5 years of age, generally beginning as frequent episodes of wheezing with respiratory infections. Additional risk factors for children include having allergies, the allergic skin condition eczema, or parents with asthma.

Young boys are more likely to develop asthma than young girls, but this trend reverses during adulthood. Researchers hypothesize that this is due to the smaller size of a young male's airway compared to a young female's airway, leading to a higher risk of wheezing after a viral infection.
Allergies

Almost all asthma sufferers have allergies. In fact, over 25% of people who have hay fever (allergic rhinitis) also develop asthma. Allergic reactions triggered by antibodies in the blood often lead to the airway inflammation that is associated with asthma.

Common sources of indoor allergens include animal proteins (mostly cat and dog allergens), dust mites, cockroaches, and fungi. It is possible that the push towards energy-efficient homes has increased exposure to these causes of asthma. 

Tobacco Smoke

Tobacco smoke has been linked to a higher risk of asthma as well as a higher risk of death due to asthma, wheezing, and respiratory infections. In addition, children of mothers who smoke - and other people exposed to second-hand smoke - have a higher risk of asthma prevalence. Adolescent smoking has also been associated with increases in asthma risk.
Environmental Factors

Allergic reactions and asthma symptoms are often the result of indoor air pollution from mold or noxious fumes from household cleaners and paints. Other indoor environmental factors associated with asthma include nitrogen oxide from gas stoves. In fact, people who cook with gas are more likely to have symptoms such as wheezing, breathlessness, asthma attacks, and hay fever. 
 

Pollution, sulfur dioxide, nitrogen oxide, ozone, cold temperatures, and high humidity have all been shown to trigger asthma in some individuals.

During periods of heavy air pollution, there tend to be increases in asthma symptoms and hospital admissions. Smoggy conditions release the destructive ingredient known as ozone, causing coughing, shortness of breath, and even chest pain. These same conditions emit sulfur dioxide, which also results in asthma attacks by constricting airways.

Weather changes have also been known to stimulate asthma attacks. Cold air can lead to airway congestion, bronchoconstriction (airways constriction), secretions, and decreased mucociliary clearance (another type of airway inefficiency). In some populations, humidity causes breathing difficulties as well.

Obesity

Overweight adults - those with a body mass index (BMI) between 25 and 30 - are 38% more likely to have asthma compared to adults who are not overweight. Obese adults - those with a BMI of 30 or greater - have twice the risk of asthma. According to some researchers, the risk may be greater for nonallergic asthma than allergic asthma.

Pregnancy

The way you enter the world seems to impact your susceptibility to asthma. Babies born by Caesarean sections have a 20% increase in asthma prevalence compared to babies born by vaginal birth. It is possible that immune system-modifying infections from bacterial exposure during Cesarean sections are responsible for this difference. 

When mothers smoke during pregnancy, their children have lower pulmonary function. This may pose additional asthma risks. Research has also shown that premature birth is a risk factor for developing asthma.

Stress

People who undergo stress have higher asthma rates. Part of this may be explained by increases in asthma-related behaviors such as smoking that are encouraged by stress. However, recent research has suggested that the immune system is modified by stress as well.
Genes

It is possible that some 100 genes are linked to asthma - 25 of which have been associated with separate populations as of 2005.
 

Genes linked to asthma also play roles in managing the immune system and inflammation. There have not, however, been consistent results from genetic studies across populations - so further investigations are required to figure out the complex interactions that cause asthma. 

Mom and Dad may be partially to blame for asthma, since three-fifths of all asthma cases are hereditary. The Centers for Disease Control (USA) say that having a parent with asthma increases a person's risk by three to six times.

Genetics may also be interacting with environmental factors. For example, exposure to the bacterial product endotoxin and having the genetic trait CD14 (single nucleotide polymorphism (SNP) C-159T) have remained a well-replicated example of a gene-environment interaction that is associated with asthma.

Airway Hyperreactivity

Researchers are not sure why airway hyperreactivity is another risk factor for asthma, but allergens or cold air may trigger hyperreactive airways to become inflamed. Some people do not develop asthma from airway hyperreactivity, but hyperreactivity still appears to increase the risk of asthma.

Atopy

Atopy - such as eczema (atopic dermatitis), allergic rhinitis (hay fever), allergic conjunctivitis (an eye condition) - is a general class of allergic hypersensitivity that affects different parts of the body that do not come in contact with allergens. Atopy is a risk factor for developing asthma.

Some 40% to 50% of children with atopic dermatitis also develop asthma, and it is probable that children with atopic dermatitis have more severe and persistent asthma as adults.

Treatment for Asthma
 
Asthma is not so much "treated" as it is "controlled". As a chronic, long-term disease, there is no cure. However, there are tools and medicines to help you control asthma as well as benchmarks to gauge your progress.

The Peak Flow Meter

A peak flow meter is a simple, small, hand-held tool that can help you maintain control of asthma by providing a measurement of how well air moves out of the lungs.

After blowing into the device, the meter reveals your peak flow number. A physician will indicate how often to test as well as how to interpret the result to determine the amount of medication to take. Some people record scores every morning while others use the peak flow meter intermittently. 

Often, each test with the peak flow meter will be judged against your "personal best" peak flow number (found during 2 to 3 weeks of good asthma control). If peak flow tests begin to decline - even before other symptoms are present - it may indicate a looming asthma attack. After taking asthma medication, the peak flow meter can be used to test the effectiveness of drug therapy.

Good Control

Asthma is considered "well-controlled" if:
Chronic and troublesome symptoms (coughing and shortness of breath) are prevented and occur no more than 2 days per week.
There is little need for quick-relief medicines or they are needed less than 2 days per week.
You maintain good lung function.
Your activity level remains normal.
Your sleep level remains normal and symptoms do not wake you from sleep more than 1 to 2 nights per month.
You do not need emergency medical treatment.
You have no more than one asthma attack each year that requires inhalation of corticosteroids.
Your peak flow stays above 80% of your personal best number.

These benchmarks can be obtained by working with a doctor and avoiding factors that can make your asthma flare up. Also be sure to treat other conditions that may interfere with asthma management.

Good control also means avoiding things that trigger asthma or asthma symptoms such as allergens. This may mean limiting time spent outdoors when pollen levels or air pollution levels are highest and limiting contact with animals. Asthma linked to allergies can also be suppressed by getting the necessary allergy shots.

Preventive Checkups

Part of good asthma control is seeing a doctor every 2 to 6 weeks for regular checkups until it is under control. Then checkups may be reduced to once a month or twice a year. 

It is a good habit to keep track of asthma symptoms and attacks and diagnostic numbers such as the peak flow measurement. Doctors and nurses will ask about these and about daily activities in order to gauge the status of your asthma control.

Medicine

 
Medication for asthma is broadly categorized as either quick-relief medicine or long-term control medicine. Reducing airway inflammation and preventing asthma symptoms is the goal of long-term control medicines, where as immediate relief of asthma symptoms is the goal of quick-relief or "rescue" medicines.

Medications can be ingested in pill form, but most are powders or mists taken orally using a device known as an inhaler. Inhalers permit medicines to travel efficiently through the airways to the lungs.

Inhaler

Medication may also be administered using a nebulizer, providing a larger, continuous dose. Nebulizers vaporize a dose of medication in a saline solution into a steady stream of foggy vapor that is inhaled by the patient.

Long-Term Control

Long-term control medicines are taken every day and are designed to prevent asthma symptom such as airway inflammation. Inhaled corticosteroids are the most effective long-term control medicine - the best at relieving airway inflammation and swelling. They are usually taken daily to greatly reduce the inflammation that initiates the chain reaction of the asthma attack.

Even if taken every day, inhaled corticosteroids are not habit-forming. However, the medicines do have side effects such as the mouth infection known as "thrush". Thrush occurs when the corticosteroids land in your throat or mouth. Spacers or holding chambers have been developed to help avoid this. Thrush can also be avoided by rinsing the mouth out after inhalation. 

Inhaled corticosteroids also increase the risk of cataracts (clouding of the eye's lens) and osteoporosis (weakening of the bones) if taken for long periods of time. 

There are other long-term control medicines available that doctors may prescribe. Most of them are taken by mouth and are designed to open the airways and prevent airway inflammation. Examples include inhaled long-acting B2-agonists (used with low-dose inhaled corticosteroids), leukotriene modifiers, cromolyn and nedocromil, and theophylline.

Quick-Relief Medicines

Quick-relief medicines relieve asthma symptoms when they occur. The most common of these are inhaled short-acting B2-agonists - bronchodilators that quickly relax tight muscles around the airways, allowing air to flow through them. 

The quick-relief inhaler should be used when asthma symptoms are first noticed, but should not be used more than 2 days a week. Most people carry the quick-relief inhaler with them at all times. Quick-relief medicines usually do not reduce inflammation and therefore should not be used as a replacement for long-term control medicines.

Emergency Care

 
If your medicines do not relieve an asthma attack or your peak flow is less than half of what it normally is, emergency medicine may be necessary. Call 911 or have someone take you to the emergency room if you cannot walk because you are out of breath or if you have blue lips or fingernails. 

Lifesaving treatments at the hospital will consist of direct oxygen (to alleviate hypoxia) and higher doses of medicines. Emergency personnel will likely administer a cocktail of short-acting B-2 agonists, systemic oral or intravenous steroids, other bronchodilators, nonspecific injected or inhaled B-2 agonists, anticholinergics, inhalation anesthetics, the dissociative anesthetic ketamine, and intravenous magnesium sulfate.

Intubation (a breathing tube down one's throat) and mechanical ventilation may also be used in patients undergoing respiratory arrest.
Children 

Although quick-relief medicines can relieve wheezing in young children, long-term control medicines will be used to treat infants and young children if symptoms are likely to persist after 6 years of age. 

Like adults, children are treated with inhaled corticosteroids, montelukast, or cromolyn. Often, treatments will be tried for 4 to 6 weeks and stopped if the desired outcome is not seen. Inhaled corticosteroids carry the side-effect of slowed growth, but the effect is generally small and is only apparent for the first few months of treatment.

Elderly

Elderly asthma care may require adjustments to prevent interactions between medicines. Beta blockers, aspirin, pain relievers, and anti-inflammatory medicines can prevent asthma medicines from working correctly and may worsen symptoms. In addition, it may be difficult for older persons to hold their breath for 10 seconds after inhalation of medicines, but spacers have been developed to help this issue.

The increased osteoporosis risk brought on by inhaled corticosteroids may be magnified in older adults with weak bones. It is common to take calcium and vitamin D pills, among other therapies, to keep bones healthy.

Pregnant Women

Proper asthma control is necessary for pregnant women in order to ensure a good supply of oxygen to the fetus. Babies born of asthmatic mothers have a higher chance of premature birth and lower birth weight. For pregnant women, the risks associated with having an asthma attack outweigh any risks associated with asthma medicines. 

Non-medical Treatments

Some people treat asthma using unconventional alternative therapies, but there is little formal data to support the effectiveness of these methods. There is research, however, that has found acupuncture, air ionizers, and dust mite control measures, to have little or no effect on asthma symptoms or lung function. Evidence is inconclusive to support or reject osteopathic, chiropractic, physiotherapeutic, and respiratory therapeutic techniques. Homeopathy may mildly reduce the intensity of symptoms, but this finding is not robust.