What is Asthma?
Learn what asthma is and what causes it.
Rob Lamberts, MD
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What is Asthma?
Breathing is important. You have to trust me on that; I’m a doctor. Everyone should practice breathing every day (hopefully you picked the habit up after reading my episode on sleep apnea). There are some conditions, however, that make breathing very difficult. This is serious because without breathing people are…dead. That’s not good. Trust me on that one as well.
What is Asthma?
The next two articles will cover a common condition that makes breathing difficult in adults and children: asthma. Asthma is very common, affecting 7% of Americans, and nearly 300 million people worldwide. Even if you don’t have asthma, this is an important disease to understand for several reasons:
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It’s common enough that you will frequently encounter people with asthma
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The symptoms are subtle, so sometimes the first sign of the disease is a major attack
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People can die from major attacks.
To understand asthma, however, I have to first explain breathing. That may sound obvious, but breathing is more complicated than you think. Next week, I’ll cover some ways to treat asthma and prevent asthma attacks.
Why People Breathe
There are two main parts of breathing: breathing in and breathing out. The purpose of breathing in is to suck air into the lungs, whereas breathing out is all about pushing air out of the lungs. That sounds obvious, but what isn’t obvious is what happens in the lungs when you do this.
What Happens in Your Lungs When You Breathe?
The lungs are where air meets your bloodstream.Two things happen when the air meets the blood:
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The red blood cells suck up oxygen from the air
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The carbon dioxide in the blood moves into the air in the lung.
Both of these are very important. Your cells need oxygen to burn energy and do the cell things they do, be they muscle cells contracting, nerve cells conducting nerve signals, or spleen cells doing whatever spleen cells do. The energy they usually burn is a sugar called glucose (see the diabetes articles for more about glucose).
“Burning” something involves combining it with oxygen – a process which releases energy stored in the substance. That’s what happens to wood in the fireplace and gas in the car. In the body, the cells combine oxygen and glucose releasing energy, water and carbon dioxide. The water is, well, water, but the carbon dioxide is toxic to the cell, and so is carried away by the bloodstream to the lungs, where it leaves the blood and is exhaled.
Why am I telling you this? It turns out that both intake of oxygen and output of carbon dioxide are really important to your body. Without oxygen, your cells can’t burn glucose and so are without energy. They suffocate. Too much carbon dioxide in your blood will make your blood acidic, and that causes all sorts of problems. The oxygen is like fuel for your car, which is necessary for it to function, whereas the carbon dioxide is like the toxic gasses released when fuel is burned; if you don’t get rid of them, everyone in the car gets sick or dies.
What Causes Asthma?
In asthma, the tubes that bring oxygen to the lungs, called bronchi, get inflamed and spasm, so that they are narrower than they should be. That affects exhaling more than inhaling because you increase the pressure in your chest cavity when you breathe out. That increased pressure pushes the bronchi closed even more. The result is a prolonged exhalation, often with a high-pitched sound called a wheeze. Let me say that again: wheezing is a high-pitched sound that happens when a person breathes out. That is why asthma is sometimes called an obstructive lung disease.
Why Do Bronchi Become Inflamed?
So why do the bronchi get inflamed? Respiratory infections, allergies, cold air, air pollution, and smoke are some of the more common causes of inflammation. A person with asthma has an increased response to these things, causing more inflammation than normal, as well as a spasm of the muscles in the bronchi. That means that what gives most of us a cough will result in wheezing in an asthmatic.
What are the Symptoms of Asthma?
Some people with mild asthma have a persistent cough only–that’s their only symptom. I’ve seen people who come in a few times each year with a cough and even mild wheezing end up having mild asthma. Other people with asthma get short of breath after a small amount of exercise. They avoid symptoms by simply avoiding exercise.
Wheezing isn’t Always Asthma
Not all wheezing is caused by asthma. Certain viruses can cause wheezing in non-asthmatics. The most notorious of these is the Respiratory Syncytial Virus, or RSV, which causes wheezing and shortness of breath and hospitalizes many young children and infants each year. Hospitalization with RSV is associated with a higher future risk of asthma, but it doesn’t guarantee it.
Exposure to smoke and to caustic chemicals like chlorine can cause the bronchi to spasm, resulting in wheezing. Though this wheeze can be life threatening, it doesn’t represent asthma.
Finally, there is a condition known as Chronic Obstructive Pulmonary Disease, or COPD, which causes significant wheezing and shortness of breath. COPD, which includes the terrible condition called emphysema, is caused by cigarette smoking, which permanently destroys lung tissue. I’ll cover this in a future article.
How Asthma is Diagnosed
People coming into the office or ER with repeated episodes of wheezing and shortness of breath undoubtedly have asthma.
So how is asthma diagnosed? Sometimes it is easy, but other times it is subtle. People coming into the office or ER with repeated episodes of wheezing and shortness of breath undoubtedly have asthma. For others, doing lung function tests is the only way to uncover the problem. In these tests, the person blows hard into a tube that measures the velocity of the air leaving the lungs. People with airway obstruction will take longer to breathe out, which usually means they have asthma.
The diagnosis is more difficult in the person with intermittent symptoms. It’s a known fact that setting foot into a doctor’s office can make symptoms mysteriously disappear. That is especially true with young children. The symptoms and the obstruction from asthma sometimes only happen outside of the office, especially in asthma that occurs with exercise. In this case, I often use a trial of asthma medication to see if the symptoms get better.
Quick and Dirty Tips
So here are my quick and dirty tips for this article:
Tip 1: Breathe
I recommend that you breathe every day. If you don’t, it will ruin your day.
Tip 2: Know the Symptoms of Asthma
You may want to visit your doctor to be evaluated for asthma if you have any of the following symptoms:
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A cough that won’t go away
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A cough that comes back every year around allergy season
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Trouble catching your breath with exercise
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Wheezing
Tip 3: Read My Next Article if You Want to Know More About Asthma
In my next article I’ll discuss how to treat asthma and how to prevent asthma attacks.
If you have questions you want answered, send them to housecalldoctor@quickanddirtytips.comcreate new email. You can find me on Twitter as @housecalldoc and on Facebook under “House Call Doctor.”
Let me remind you that this podcast is for informational purposes only. My goal is to add to your medical knowledge and translate some of the weird medical stuff you hear, so when you do go to your doctor, your visits will be more fruitful. I don’t intend to replace your doctor; he or she is the one you should always consult about your own medical condition.
Catch you next time! Stay Healthy!
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