Overview

Asthma, known as bronchial asthma is a chronic lung condition that makes breathing hard. It is characterised by chronicity, requiring continuous medical supervision as it does not resolve on its own. When someone has asthma, their airways become narrow and inflamed, causing symptoms like wheezing, chest tightness, coughing, and shortness of breath. 

This condition affects about 25 million people in the U.S., including 4.6 million children, with equal prevalence among men and women.^1,2 Asthma can start at any age, but it is common in children often beginning at ages 2 to 6 although it can also develop in adulthood. 

The primary goal of asthma treatment is to manage symptoms and prevent or alleviate asthma attacks.

How asthma attack happens

An asthma attack occurs when the muscles surrounding your airways tighten, leading to narrowed air passages, swelling of the airway lining, and increased production of thick mucus, resulting in the obstruction of the airflow. 

This tightening of the airways causes wheezing, a characteristic sound when breathing. It is also known as an exacerbation or flare-up, indicating uncontrolled asthma symptoms.

Triggers such as pollution,³ tobacco smoke, and exercise can worsen asthma symptoms by irritating the already sensitive airways and this often leads to frequent doctor visits.

Causes and triggers of asthma

Researchers have been unable to understand the exact cause of asthma.⁴ However, certain factors increase the likelihood of developing the condition:

1. Allergies: Having allergies can increase the risk of developing asthma. They are the most common asthma triggers. Examples include animal dander, dust mites, ‘cockroach droppings, pollen, and moulds, both indoor and outdoor varieties.^5,6
2. Environmental factors: Exposure to irritants such as allergens, toxins, fumes, and second- or third-hand smoke can trigger asthma development.^7,8
3. Genetics: A family history of asthma or allergic diseases can elevate the risk of developing asthma. If one of your parents has asthma, you might be 3 to 6 times more likely to get it than someone whose parents don't have it.⁹
4. Respiratory infections: Certain respiratory infections, like respiratory syncytial virus (RSV), can harm the developing lungs of young children, potentially leading to asthma later in life.

Other triggers for asthma symptoms include:

• Physical activity or exercise
• Strong emotional expressions
• Gastroesophageal reflux disease (GERD)
• Certain medications, such as aspirin, NSAIDs, and beta-blockers
• Sulfites found in food items and beverages
• Dust mites, mould, pests, and pets
• Strong chemicals or odours
• Occupational exposures to various substances at work

Common signs and symptoms of asthma

Asthma symptoms may vary during each flare-up, and you may not experience all of them every time.¹¹ They may include:

1. Tightness, pain, or pressure in the chest
2. Coughing, particularly more noticeable during nighttime
3. Difficulty breathing, resulting in shortness of breath
4. Wheezing, characterised by a whistling sound during breathing¹²

Using inhalers for asthma treatment

Many asthma medications are administered through inhalers or nebulisers.¹³ These devices facilitate the inhalation of asthma medication through the mouth, delivering it directly to the airways. 

Asthma patients usually require two types of medications: quick-relief medicines for immediate symptom relief and long-term control medicines to manage airway inflammation and prevent symptoms.

Quick-relief medication, like inhaled short-acting beta2-agonists,¹⁴ swiftly relaxes tightened airway muscles to improve airflow.

How they work

The inhaler works by relaxing the muscles in the airways, making it easier to breathe. Salbutamol inhalers are commonly referred to as "reliever" inhalers because they provide rapid relief from breathing difficulties when needed.¹⁵ 

Typically, alongside a reliever inhaler, you'll also be prescribed a "preventer" inhaler to help prevent symptoms. The preventer inhaler is used regularly, usually on a daily basis.

The types of inhaler delivery devices are:

Metered dose inhaler (MDI)

A metered dose inhaler (MDI) is a small device you hold in your hand. It has a metal canister inside that holds the medicine. When you press down on the canister, it releases a specific amount of medicine. 

The canister is surrounded by a plastic cover with a mouthpiece for you to breathe through. There is medicine mixed with a substance called a surfactant inside the canister, which helps to spread the medicine into tiny particles. It also has a propellant which pushes the medicine out when you press down on the canister.

Advantages

• Easy to carry around
• Less risk of bacterial contamination
• Capable of delivering multiple doses

Disadvantages

• Requires precise coordination between pressing the device and inhaling
• Not suitable for individuals sensitive to or affected by propellants with heart-related issues
• Medicine may end up in the mouth and throat
• The propellant used may be flammable

Inhalation accessory devices

Inhalation accessory devices work alongside metered dose inhalers to improve their effectiveness. These devices are attached to the mouthpiece of the inhalers, helping to expand and slow down the high-pressure spray into a fine mist. 

The two main types are:

1. Spacers: Spacers create space for the aerosol spray to slow down and form a fine mist. They can be used by children with a pediatric mask and come in two varieties:
   • Reverse-flow spacers: These devices redirect the flow of medication away from the spacer's mouthpiece and alert the user if they inhale too quickly
   • Open tube spacers: These extensions provide extra space to slow down the spray.

• Valved holding chambers: Valved holding chambers feature a one-way valve that keeps the medication mist inside the spacer until the patient inhales it through the valve. Most of these devices alert the patient if he inhales too quickly.

Advantages

• Improved drug delivery efficiency
• Prevents exhalation of air into the device
• Eliminates the requirement to coordinate inhalation with device activation 
• Decreases the amount of drug deposited in the mouth and throat

Disadvantages

• Prone to potential bacterial contamination; necessitates regular cleaning
• Static electricity may decrease drug delivery to the lungs
• Larger in size

Dry powder inhalers (DPI)

Dry powder inhalers (DPI) are devices that hold medication in tiny particles within a capsule or blister. Before inhaling through the mouthpiece, the blister or capsule is pierced. Unlike other inhalers, dry powder inhalers do not require a propellant and are activated by the patient's breath.

Here are some types of dry powder inhalers:

• Diskus: This device has a disk-like shape and contains a coiled strip of blisters punctured using a rotating wheel
• Aerolizer: Made of plastic, this device features a button for puncturing capsules
• HandiHaler: A spherical plastic device with a button for puncturing capsules
• Twisthaler: This device includes a twisting mechanism to deliver measured doses of dry powder medication
• Flexhaler: Utilizing a twisting motion, this device punctures capsules for medication delivery

Advantages

• Portable and easy to carry
• It does not require a propellant
• Activated by the patient's breath, removing the need for coordination
• Eliminates the need for spacers

Disadvantages

• Humidity can cause the powder to clump together, hindering dispersal
• Medication may be deposited in the throat
• They require a sufficient inhalation flow rate, making them unsuitable for patients with acute asthma attacks or children with reduced lung function

Nebulisers

Nebulisers are electric devices that convert liquid medication into breathable aerosol particles through nebulisation. The tabletop nebulisers can be connected to wall outlets, while portable models operate on batteries.

While studies indicate that nebulisers are not superior to MDIs in terms of effectiveness,¹³ they offer an alternative option for patients. Nebulisers are particularly useful for individuals who struggle with coordinating MDI usage or prefer a slower medication delivery.

They are beneficial for patients who are too ill or young to use other inhalation devices and can be used with a mouthpiece or mask.

Advantages

• Patient coordination is unnecessary
• Beneficial for individuals unable to utilise the alternative inhalation devices
• Capable of administering large medication doses

Disadvantages

• Higher price
• More challenging to transport
• Requires more time for setup and medication administration

Dosage guidelines for inhaler usage

For both adults and children:

• Take 1 or 2 puffs of salbutamol as needed, up to 4 times in 24 hours
• During an asthma attack, you can use the inhaler more often, up to 10 puffs
• Wait 30 seconds between each puff and shake the inhaler each time for best results

Tips on how to use the inhaler  

Poor use of inhalers is a common practice. Research suggests that only 30% of people know how to use their inhalers properly.^16,17 See how to use it:

Metered dose

1. Shake the inhaler before each use
2. Exhale completely before inhaling the medication
3. Hold the inhaler in the right position
4. Inhale deeply while simultaneously pressing the inhaler to release the medicine into your mouth. Then, hold your breath for as long as you can (at least 5 seconds)
5. Remember to shake the inhaler between each puff

Dry inhaler

1. Avoid tilting the inhaler while loading the dose
2. Fully exhale before inhaling, and take a deep, complete breath
3. Do not exhale into the inhaler
4. Close the inhaler after each use

Summary

Inhalation therapy is a crucial aspect of asthma management, providing both quick relief and long-term control of symptoms. It is important to know the different types of inhalers, proper usage techniques, and dosage guidelines are essential for effective asthma treatment.

Understanding asthma triggers and working closely with healthcare providers are pivotal for achieving optimal management and enhancing overall health.