Asthma is caused by the sudden contraction of smooth muscles in the airways of the body. This is normally due to unusually viscous mucus being produced in abundance in the bronchial mucous glands. One of the primary causes of asthma is the narrowing of bronchial tubes because of inflammation. Asthmatics are overly sensitive (hyperreactive) to stimulants in the environment that can cause the bronchial muscles and tubes to contract. Tubes become irritated and swollen, in turn producing excess mucus and blocking the flow of air. While asthma is often hereditary, it can also be acquired through prolonged exposure to substances such as solder and sulphite.
In severe asthma attacks, the accumulation of additional mucus from the bronchial tree can also inhibit airflow within the airways, making it more difficult for an asthma sufferer to breathe. There are several things that can trigger an asthma attack, including exercising and traffic fumes. To overcome an attack, an asthma inhaler can be used to relax the muscles and widen the bronchial tubes so that normal breathing can be resumed.
How do inhalers help asthmatics?
Metered-dose inhalers (MDIs) are small hand- operated devices that can send out an aerosol with a precise amount of medication into a small chamber. The user then breathes in the drugs through the mouthpiece, and the medication goes directly to the airways and lungs.
The inhaler, or puffer, consists of a plastic body and a pressurised canister that contains the medication and a propellant vapour. Large plastic, valved holding chambers, or spacers, can be fitted to the mouthpiece of the inhaler, if desired, so that the user has more time to inhale the aerosol.
For the treatment of asthma, the user usually has two colour-coded inhalers. One is a ‘preventer’ inhaler which contains medication that has to be used on a regular basis, and the other is a ‘reliever’; the latter is used in the event of breathlessness or a sudden asthma attack.
Top 5 Facts: Respiratory treatments
1. Breathe easy
Ancient cultures in India, Greece and Egypt discovered that inhaling the smoke or vapours from medicinal leaves and herbs helped relieve a number of respiratory problems.
Ancient civilisations also found that the smoke produced by burning incense (a mix of medicinal plants, minerals and gum resins) eased tension. It became common practice to use it to purify the air and during religious ceremonies.
3. Pressurised inhalers
These were invented by Riker Laboratories in 1956, after the daughter of the company’s president asked why she could not use her asthma medication in the same way as her hairspray can worked.
In 2009, the US banned the use of CFCs as propellants in inhalers as they could be harmful to the ozone layer. Since then less harmful hydrofluorocarbons (HFCs) have been used instead.
Over 5 million people in the UK suffer from asthma, and there are over 1,100 asthma-related deaths per year; 90 per cent of these are preventable with the correct use of an inhaler.
Discover more amazing science in the latest issue of How It Works. It’s available from all good retailers, or you can order it online from the ImagineShop. If you have a tablet or smartphone, you can also download the digital version onto your iOS or Android device. To make sure you never miss an issue of How It Works magazine, make sure you subscribe today!