1 Childhood asthma

In this section, you will explore the experiences of those who have a diagnosis of childhood asthma and have often been in hospital with severe asthma attacks during childhood. You will explore the common condition found in children and young people, and how it is assessed, diagnosed and managed on a day-to-day and acute basis. You will hear Chloe’s experiences as a young person with asthma and how she copes with asthma and having an asthma attack; a parent of a child with asthma explaining how it felt to be part of the diagnostic process; and when children are hospitalised with acute episodes.

Explore Figure 1 to learn more about the common signs, symptoms and risk factors of asthma.

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Figure 1  Signs, symptoms and risk factors of asthma in children

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Figure 1 is a diagram in two parts showing the signs and symptoms of asthma, and the risk factors. There are two series of circles linked together with lines around a central circle. The first has ‘Signs and symptoms’ at the centre, with: ‘wheezing’, ‘coughing’, ‘rapid breathing’, ‘laboured breathing’, ‘chest hurts’, ‘low energy’, and ‘fatigue’ arranged around it. The second has ‘Risk factors’ at the centre, with: ‘allergies’, ‘family history’, ‘respiratory infections’, ‘low birth weight’, ‘exposure to second hand smoke’, ‘low socioeconomic status’, and ‘living in an urban area’ arranged around it.

Figure 1  Signs, symptoms and risk factors of asthma in children

Activity 1 Biological development of the respiratory system (children) and pathophysiology of childhood asthma

Timing: Allow 60 minutes

Watch the following video and on a piece of paper create a labelled diagram that identifies the difference between a normal and asthmatic airway. Then produce a list of ‘triggers’ that might affect asthmatics.

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Transcript: Video 1 Asthma pathophysiology / Respiratory system diseases

INSTRUCTOR

Before we talk about what asthma looks like, let’s take a look at a normal airway. So we’ve taken a cross-section of somewhere along the airway. Asthma is a small airway disease, so this is not the trachea or the stuff in your throat, but in your chest.

And one of the important players in the calibre of the structure of the airway that I want to start with is the smooth muscle layer. So we’ll use red for muscle. And this layer controls the diameter of the opening, the diameter of the lumen.

Of course, outside the muscle, there’s other things too. There’s connective tissue and cartilage, depending on if you’re high up enough on the airway. Those things are not really as affected by asthma, so we’ll just leave it like this. So we got our smooth muscle, which, smooth muscle, remember, you can’t control consciously. It reacts to the environment and usually keeps our airway nice and open like this. Label that here, smooth muscle. The inside that we have – a layer of the mucosa. So we call it the mucosal layer. Let me just label that, the mucosa. That basically coats the inside opening of the airway.

And within this layer, it’s very important that we have these glands that can secrete mucus into the lungs. They’re, therefore, lubricating the opening and keeping our lungs moist. And also when there is inflammation, or there are foreign bodies we have to get rid of, the mucus that they secrete is important in clearing out the area. So when we cough, and we cough up the phlegm, the phlegm comes from these glands that secrete the mucosa.

So they’re everywhere in the mucosal layer. And of course, here we have the lumen. This is where the air actually moves in and out. It is dry, but nice and lubricated by the mucus. So this is a quick look at what the normal lung, the normal cross-section of the airway, looks like.

And now let’s look at what happens when this person is having asthma. As you know, asthma comes in attacks. So most of the changes happen during an attack. Depending on the severity, this person might get it more often than the next patient.

So first, we still have our muscular layer. But now the lung is in spasm. The muscles are spasming, which means it’s constricting and the opening is going to be much smaller. The connective tissue, like the cartilage and other things, are still out there. So I’ll still draw it like this. But the important thing to focus on right now is the fact that the muscular layer has thickened, and it’s clamping down on this opening. In addition, the mucus layer, which is nice and round here, that I’ve drawn has swelled up in reaction to the inflammation.

So instead of a nice round opening like this, now we have this amorphous shape that further clamps down on the opening. So now look at what has happened to our lumen. It’s much smaller. And to make matters worse, don’t forget the glands.

So the glands are still here, but this time, they are also reacting to the immune response. And as a result, they’re filling up with mucus, and they’re secreting it into the lumen that’s already narrow and blocked off. So now we’ve got this swirling mucus in here.

That only makes matters worse. So look at the difference between air going through this nice, big opening and air trying to get through this. So between the constriction and all the fluid in there, we’re going to have little bubbles. That’s why you hear the popping and the wheezing when you listen to a person having an asthma attack.

The wheezing comes from the obstruction, both from mechanically narrowing this area and the extra fluid in there from these glands going crazy. So that’s how it happens. But why does this whole thing take place? What triggers asthma?

Well, that is the million dollar question, because there are so many things in the environment. What I’m drawing here are – it could be pollution. It could be smoke. It could be food or dander, anything that this particular person reacts to. These are the allergens in the air.

And when they get into the body, our body has an immune response that reacts to anything that’s foreign. Some people react more than others. And we have these antibodies that look like Y-shaped molecules. So these, in an immune reaction, tend to be IgE. That’s just the name of these antibodies.

Now the body has a tricky memory system. If it’s the first time that it’s seen these allergens, you might only get two IgEs because they’re working hard to make new ones to recognise them. But the third or fourth time, every time you get exposed, because the memory is still there, it’s easier to make the IgE each time. It’s like fighting an enemy that you’ve already fought before. So the IgE actually increases in number.

So the size of this IgE response is proportional to the size of this immune response or to this allergic response, I should say, because when the immune response goes haywire, responding to something that’s foreign and trying to fight it off, that’s called an allergy. So we’ve got these foreign allergens, whatever the trigger is, with the IgE. The job of the IgE is to recognise and pick up these foreign particles.

The IgE is in the same family of antibodies that help us fight off infections. But in this case, it goes to search for a cell we call it the mast cell. It’s spelled mast like the mast on a ship.

And inside the mast cell, it’s just floating around our body carrying little pockets of a molecule we call histamine. And histamine is the main player in any allergic reaction. Remember, if you have ever taken anything to fight off an allergy, there’s a class of drugs called the antihistamines.

So histamine is just usually walled off in the mast cell and not in our system. But the IgE antibodies we just talked about, they are friends with the mast cells. And only when they’re carrying a foreign body like this do they find a mast cell and attach to it. So every pair of the IgE that has picked up an allergen will go then look for a mast cell to attach to it like this.

This attachment right here wakes up the mast cells. So all these little pockets inside it open up. The histamine then flows out of the mast cell like this and floods into our system, into our bloodstream, causing allergic reactions everywhere. This is why you sneeze and your eyes water, you can get hives.

The whole cascade of that allergic reaction is thanks to these little histamine molecules. And in the lungs, if this person has asthma, this is exactly what happens as a result of the histamine. Let me just draw a few more particles here to show you.

And voila. We get this constriction. We get the mucosal swelling, and we get the wheezing. So asthma is really an immune response going overboard as all allergies are. It’s a part of our body’s natural response to a foreign body that then causes us harm by reacting too strongly and releasing things that cause us discomfort.

So to sum up the pathophysiology of asthma, remember, first, we’ve got the muscular layer thickening and constricting. Then we’ve got the mucosal layer swelling up. And third, we have the glands overproducing the mucus that then floods the already constricted opening.

End transcript: Video 1 Asthma pathophysiology / Respiratory system diseases

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Video 1 Asthma pathophysiology / Respiratory system diseases

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Discussion

Your diagram might have had the following features shown in Figure 2.

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Figure 2  How airways are affected by asthma

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Figure 2 is a diagram showing how airways are affected by asthma. To the left is a drawing of a man with the lungs and airways visible. The centre part of the diagram shows a cross section of a normal airway and labels the muscle and airway wall. The final part of the diagram shows an airway during asthma symptoms. The airway is narrowed allowing limited airflow; the muscles are tight, constricting the airway, and there is mucus further restricting the flow of air.

Figure 2  How airways are affected by asthma

You may have identified the following triggers:

• infections e.g. a cold
• allergens such as pollen, animal fur or dust mites
• cigarette smoke
• pollution
• medicines
• mould
• weather changes, such as cooler weather in the winter
• exercise.

As a person working with or caring for children and young people with asthma, it is important that you are vigilant to signs of deterioration in health and wellbeing and that you know how and when to escalate any concerns. It is often useful to understand how asthma is diagnosed. In the next section you will look at the assessment and diagnosis of asthma.