What is Asthma?

Asthma is a common condition that affects more than 10% of the population. Asthma is defined as reversible airway obstruction. It is caused by narrowing of the lower airways due to inflammation, and is therefore a disease of airway inflammation. Asthma patients might be normal most of the time, but when the disease exacerbates, the patient would cough, wheeze, and feel tight in the chest and short of breath.

Asthmatic tendency is genetically determined, but the disease is triggered by external factors. Asthma most commonly starts during childhood, and the two most common causes are allergy and infection. Before the age of three, asthma is more commonly caused by virus infection, and the most common culprits are Respiratory Syncythial Virus (RSV), Rhinovirus and Adenovirus. Acute infections with these viruses can lead to croup, and patients develop high fever, cough, wheezing and dyspnea. In susceptible individuals, croup during the first two years of life can subsequently lead to recurrent wheezing illnesses.

However, this problem often improves with age and goes into remission by about 8 years of age. Allergic asthma, on the other hand, often persists into adulthood. Even in those patients who seem to outgrow their asthma during their teens, recent studies have shown that many of them will develop asthma symptoms again in their 30s and 40s. The majority of patients with allergic asthma also suffer from allergic rhinitis, since both conditions are caused by allergen exposure. The most common allergens include house dust mites, cockroach, animal dander, mold spores and pollens.

Reference information:  http://www.allergy.hk

The information aims to provide educational purpose only. Anyone reading it should consult physician before considering treatment and should not rely on the information above.

Asthma diagnosis - Lung Function Test

Asthma is characterized by reversible airway obstruction. That means the airway narrowing in asthmatic patients should be, at least at the outset, fully reversible. As the disease progresses without treatment, airway remodeling occurs and this leads to irreversible loss of lung function.

Patients with asthma often present with chest tightness, shortness of breath and wheezing. However, chronic cough is an early sign of asthma, and many patients might not experience wheezing. It is now recognized that asthma patients should receive treatment early on in order to prevent irreversible loss of lung function, especially in children. It is therefore important to make a diagnosis early so that treatment can be started.

Lung Function testing is an essential tool in asthma management. At the Centre for Allergy and Asthma Care, we employ the KoKo Spirometer for lung function testing. All asthmatic patients should undergo spirometry testing at baseline and periodically during treatment to monitor their progress.

Some patients with asthma and chronic cough rarely develop wheezing and airway narrowing. Regular spirometry testing will therefore be normal. For these patients, inhalation challenge with methacholine will show bronchial hypersensitivity. We employ the KoKo DigiDoser to perform inhalation challenge. This computer-controlled dosimeter can accurately administer dosages for inhalation followed by spirometry measurements. We also perform lysine-aspirin inhalation challenge to diagnose aspirin-sensitive asthma, and allergen challenge in special circumstances such as occupational asthma.

Reference information:  www.allergy.hk

The information aims to provide educational purpose only. Anyone reading it should consult physician before considering treatment and should not rely on the information above.

Cough in Children – quick tips for parent

As a parent, hearing your child cough may make you feel uneasy, yet an occasional cough doesn't always mean there is a problem. Cough protects your child's body by removing mucus, irritating substances and infections from his or her respiratory tract.
Children can cough several times a day and have coughing episodes lasting up to a couple of weeks if they have viral infections. However, coughing that lasts more than two to three weeks should prompt a visit to your physician.

Acute Cough in Children (Two Weeks or Less)
The majority of children have brief repeated periods of coughing due to viral upper respiratory tract infections, such as the common cold. Healthy preschool children in day care can have up to eight viral respiratory infections with a cough every year, each lasting about 10 days.
Infrequently, a cough occurs because of a foreign body in the airway. This may occur after an episode of choking, but sometimes the choking episode might not be noticed, especially in younger children. See your physician quickly if you think this is possible.

Causes of Chronic Cough
There are many different causes for a persistent or chronic cough in children.

·         Asthma
Most children with asthma have inflamed or swollen airways, which commonly cause wheezing. But sometimes the only symptom is a cough that is made worse by viral infections, that happens while your child is asleep, or may be triggered by exercise and cold air.

·         Nasal and Sinus Disease
Postnasal drip caused by rhinitis or a sinus infection (sinusitis) can produce chronic cough. Usually other symptoms are present, but sometimes the only symptom you notice is the cough.

Allergic rhinitis may be seasonal or year-round. The seasonal allergy, often called "hay fever," typically occurs in the spring, summer or fall. Symptoms include sneezing, stuffy or runny nose and itching in the nose, eyes or on the roof of the mouth. When the symptoms are year-round, they may be caused by exposure to indoor allergens such as dust mites, indoor molds or pets. An allergist can perform testing to find out to what your child is allergic.

·         Stomach and Esophageal Causes of Cough
In some children, the cause of chronic cough is stomach fluid moving back up the throat. This is called "reflux" and may occur silently without heartburn. Some children may develop a hoarse voice and/or choking as symptoms. To determine if this is the cause, your physician may perform tests to see if acid is refluxing up out of the stomach.

·         Post-Viral Cough
After having a viral respiratory infection, otherwise healthy children can have a cough lasting for weeks. There is no specific therapy for this cough, which eventually goes away. Cough suppressant medications can be tried in school-age children, but they don't always solve the problem.

·         Bacterial Infection of the Lower Airway
Bacteria sometimes can infect the lower airways and cause irritation and cough. It's unknown why this happens, and sometimes the best course of action isn't clear. Your physician will help you sort out whether this may be relevant in your child.

·         Inhaled Foreign Body
Foreign bodies, such as toys and food, can be accidentally inhaled at any age, but most commonly occurs at ages two to four years. It can cause a cough to persist for many weeks to months until it is discovered.

·         "Habit" Cough
This is a persistent cough that has no clear physical cause. It occasionally persists after a simple viral respiratory infection. The cough is typically dry and repetitive or is a "honking" cough. Habit cough usually occurs only when your child is awake, not sleeping. A neuromuscular tic can also cause this kind of cough.

·         Irritant Cough
Exposure to tobacco smoke and other pollutants (smoke and exhaust from wood burning, air pollution and exhaust from vehicles) can lead to cough and may worsen the cough associated with asthma or rhinitis.

Treatment
If your child has a daytime cough after a viral respiratory infection, it usually doesn't need any specific treatment-particularly if it goes away in one or two weeks.
The main treatment for chronic cough should be based on the underlying cause. This search for the cause usually involves visiting your physician. Also visit your physician if your child's cough is increasingly frustrating, persists longer than you think is reasonable, if blood is coughed up or if the cough interferes with your child's daily activities.
Over-the-counter mucous thinning agents such as guaifenesin, and cough suppressing medications such as dextromethorphan can be tried. Although most of the over-the-counter cough medications are not thought to be particularly effective, it is possible that one might work better in your child than in other children.
If you think your child may have asthma, make an appointment with an allergist/immunologist, often referred to as an allergist. An allergist is the best physician to diagnose and treat this disease.

Healthy Tips

• A cough protects your child's body by removing mucus, irritating substances and infections from his or her respiratory tract.
• If your child has a cough that lasts more than two to three weeks, schedule a visit with your physician.
• Coughing that lasts more than two weeks is considered chronic. It may be caused by asthma, allergic rhinitis (hay fever), reflux or other causes. An allergist is often the best specialist to determine the cause.

Reference source: http://www.aaaai.org/patients/publicedmat/tips/coughinchildren.stm

The above information serve as an education purpose only, you are encourage to consult with your allergist for appropriate diagnosis and treatment.