Asthma: Risk factors, symptoms and assessment: Dr Peter Bremner

Video transcript

I’m Peter Bremner. I’m a respiratory physician and I’ve been part of the Advisory Board for about 10 years.

What is asthma?

Asthma is a disease characterised by narrowing of the bronchial tubes and that narrowing is driven by inflammation which has two effects: it causes swelling of the tubes and it causes the muscles around those tubes to constrict. So when the tubes are narrow you feel more breathless because you can’t move the air in and out. When they are wide open you can move the air in and out much more easily and so you don’t tend to feel breathless. So as a result of that narrowing you tend to have symptoms such as wheezing, or chest tightness and breathlessness.

What are the risk factors for asthma?

Asthma is a very complex disease and we don’t truly understand why people get asthma. We don’t have a cure for asthma but we have very effective treatment that can abolish all asthma symptoms.

We know that asthma is related in part to your genetic predisposition and we know it’s related in part to your environmental exposures during various periods of your life, and it’s a combination of your genes and your environmental exposures that contributes to the development of asthma. That combination varies from patient to patient and in some it might be almost entirely environmental and in some it might be predominantly genetic. But each patient needs to have their basic substrate to develop asthma and there are a number of factors that can influence whether that substrate ultimately turns into asthma.

What are the symptoms of asthma?

When you’re having a flare-up, that’s generally characterised by some increase in asthma symptoms, those symptoms vary between patients but typically as things are escalating you get more breathless, you’ll develop a cough with wheeze and chest tightness. Those symptoms vary between individuals and some patients may find they just wake up at night or wake up early in the morning, but typically people are feeling breathless and wheezy – they’re the most common symptoms.

What triggers asthma symptoms?

There are a number of conditions or situations that can aggravate asthma, most notably exposure to allergens such as pets or dust or grass, there is a number of very common allergens that can precipitate this narrowing of the airways that we talked about before. You can have irritants such as tobacco smoke or certain strong smells that can also precipitate asthma.

The other common cause of difficult asthma is people who don’t actually take their medication, so that’s probably the most common cause of asthma symptoms is people who have asthma but don’t take their medication correctly.

How is asthma assessed?

It’s important to recognise that asthma symptoms are non-specific. There are a lot of people who have breathlessness, wheeze and chest tightness who don’t actually have asthma. The critical thing or diagnostic feature about asthma is to have abnormal lung capacity and we measure that abnormal lung capacity with a test called spirometry.

So it’s very important when you see your doctor and he makes a diagnosis of asthma that he performs spirometry to confirm that your symptoms are actually due to asthma because a lot of those symptoms can be present in many other diseases.

It’s quite possible to grow out of asthma and so it’s important that your doctor measures your breathing on a regular basis to determine whether it’s normal or still abnormal, because if it’s normal then we would want to reduce the dose of your anti-inflammatory medication so that you are on the lowest dose possible to keep you free of symptoms.

So measuring lung capacity or spirometry is a very important part of your on-going assessment of asthma so that we know we’re actually treating the correct disease.