Asthma

Asthma is a disease that causes the airways to be chronically inflamed and hyperresponsive. The asthmatic will have periods with no symptoms, or mild symptoms only, and then there will be periods when the symptoms worsen. If the symptoms become severe then this is called an asthma attack. An asthma attack can be life-threatening.

In an asthma attack, the bronchi and bronchioles become inflamed, causing them to become narrowed, which reduces the amount of air that can pass through. Furthermore, the muscles that surround the airways constrict. There is also increased mucus production. Mucus is a thick sticky liquid that can further block the airways.

Causes
There are a variety of factors that determine whether someone will get asthma, such as genetics and exposure to pollution. If a person has asthma it usually begins in childhood and continues throughout the person’s life.

An asthma attack occurs when the asthmatic is exposed to allergens (such as dust mites, furry animals, pollen, mold), or irritants (such as cigarette smoke or pollution), or certain medications (such as NSAID and beta-blockers), or other factors (such as cold weather, sudden exercise, upper respiratory tract infection). These factors can trigger an asthma attack, but triggers vary from person to person. Sometimes it may not be possible to identify the particular trigger that caused the asthma attack 

Signs and Symptoms
Asthma is a condition that has varying severities, from mild to severe. Cough, wheeze and chest tightness are common symptoms.

In an asthma attack these symptoms acutely worsen. There will also be shortness of breath, often with a decrease in oxygen saturation. The patient may be using accessory muscles to breathe. There will be a prolonged expiratory phase. An asthma attack can be life threatening.

Investigations
Oxygen saturation should be continuously monitored in patients with an exacerbation of asthma.

Auscultation normally reveals a wheeze. The wheeze is the sound of air moving through the narrowed airways. The wheeze is usually loudest during exhalation. However if no breath sounds are heard then this may be because inflammation is severe preventing the air passing through. Therefore, to hear no breath sounds is an emergency

A chest x-ray is not required to diagnose an asthma attack. However, sometimes it may be required to exclude other causes of respiratory distress. If a chest x-ray is performed then it usually shows hyperexpansion. Hyperexpansion is due to air being trapped inside the lung, due to the patient being unable to exhale adequately out the narrowed airways.

Treatment
Oxygen should be given to any patient that is short of breath.

Inhaled beta 2 agonist drugs (such as a Salbutamol nebulizer) should be administered as these cause the air passage to widen (bronchodilation). Regular or continuous inhaled beta agonists can be administered as required. 

Inhaled anticholinergic drugs (such as Ipratropium nebulizer) can also be added if required. These cause the smooth muscles inside the airways to relax, which enables further bronchodilation.

Corticosteroids (such as oral Prednisolone or intravenous Hydrocortisone) should be administered for moderate to severe cases, although these take up to six hours for effect.

Intravenous Magnesium Sulphate may be added for severe cases that are not responding to the above medications.

Long Term Management
Patients with asthma should carry around a beta 2 agonist inhaler (such as Salbutamol inhaler). This should be self administered whenever symptoms present.

Patients who have more severe asthma also benefit from a corticosteroid inhaler, which is self administered on a daily basis. Patients who have even more severe asthma may need additional medications.

It is important that each asthmatic identifies which allergens or irritants cause them to have asthma attacks. Care should then be taken to avoid those triggers. When a trigger cannot be avoided, then administration of the beta 2 agonist inhaler (such as Salbutamol) is required.

The patient can monitor their lung function daily by using a small device called a peak flow meter. This is a quick and simple test that the patient can do themselves each morning in their own home.