Learn if your child’s unending hacking is because of asthma or if their persistent condition is down to other reasons.
“My child has a cough that doesn’t seem to go away.” Parents raise this common concern to both paediatricians and general practitioners. In this article, I will cover common causes of chronic cough in children and ways to manage it.
First, the basics. What is considered chronic? In children, this is a cough that lasts more than four weeks. This is because the majority of cough caused by common colds resolve within one to three weeks.
What is a cough? A cough is a sudden expulsion of air from the lungs with a characteristic sound. Irritants and germs are cleared from the lungs in this process. This is an important concept because you’ll need to understand that the cough is not the disease itself. Indeed, the ability to cough is actually a protective mechanism.
I have patients with muscle disease who are unable to produce a good cough, and hence, are more prone to lung infections. To give an analogy, coughing is like a fire sprinkler that sprays out water if there is a fire in the room. The fire is like the disease ― some “small” fires like the common cold resolves over time, some “medium” fires (like many causes of chronic cough) will need some extra help from the doctor in order to extinguish them. It is helpful to have some basic understanding of the structure of the respiratory system (see diagram below).
The airways of the chest start from the trachea ― called the first generation airway. The trachea divides into two to form the left and right main bronchus ― the second generation airway.
From then on, each bronchus divides into two or more smaller airways, up to 23 generations, and the smallest airways are called bronchioles. You can see from the diagram that this is like a tree branching into smaller and smaller branches. Hence, there are tens of thousands of bronchioles!
“Coughing is like a fire sprinkler that sprays out water if there is a fire in the room. The fire is like the disease…some “medium” fires (like many causes of chronic cough) will need some extra help from the doctor in order to extinguish them.”
1. Asthma
Asthma is a disease of the small airways, which are narrowed and produce increased mucus. Besides cough, children with asthma usually wheeze, and may have other symptoms such as shortness of breath and chest tightness. As their wheezing may not be heard by parents, a doctor is often required to detect it through the stethoscope.
Clues that point toward an asthma diagnosis include: Viral infections triggering wheezing frequently, a cough that is worsened after laughing or exercise, or a lingering cough that worsens in the early hours of the morning. Effective and safe inhaled medications are now available to control asthma in children, so these children should be able to live an active life and exercise normally.
2. Upper Airway Cough Syndrome (UACS)
Many local people refer to this condition as “sinus”, although most people do not know what “sinus” really means. UACS ― the new medical term for postnasal drip ― is a condition caused by mucus draining down from the nose or paranasal sinuses (see diagram below). The paranasal sinuses are air-filled spaces in the facial bones which are connected to the nose.
In Singapore, allergic rhinitis is very common. This is a condition where the passages of the nose are inflamed and causes symptoms such as sneezing, itchy nose, runny nose, blocked nose and postnasal drip. The postnasal drip may also cause a chronic cough. Allergic rhinitis often occurs in preschool children, and is commonly triggered by allergens such as house dust mites and pet animal dander (shed animal skin). If allergic rhinitis is not well controlled, the inflammation of the nose can extend into the paranasal sinuses, causing sinusitis (inflamed paranasal sinuses) in older children, teens and adults.
Clues that point to a UACS diagnosis include prominent nasal symptoms, as well as signs of allergic rhinitis on physical examination. Often, a UACS cough isn’t a true cough, but rather a throat-clearing sound. Again, effective medications are now available to control allergic rhinitis and to prevent it from worsening into chronic sinusitis, which is much more difficult to treat.
3. Protracted Bacterial Bronchitis (PBB)
Wait before you say you know what this is because it isn’t the usual “bronchitis” a GP or paediatrician hears on detecting wheezing or abnormal sounds in an ill child’s chest. This is a new discovery from recent research, so new that it is not found in many medical textbooks and you do not hear many doctors talk about it.
PBB is caused by bacteria growing and being very “sticky” on the larger airways (not the smaller airways like asthma or the usual small airway “bronchitis” that you hear doctors talk about). However, in this condition, the bacteria strangely does not cause fever, or wheezing, but rather an annoying phlegmy cough that may last for months. Other than the phlegmy cough, a child with PBB usually has a completely normal physical examination.
“Although symptoms are usually more annoying than harmful in the short-term, research shows that if it’s left unchecked, PBB may possibly lead to damaged airways (a condition called bronchiectasis).”
Don’t get me wrong ― this is not a new condition that has come to plague human beings, but rather a newly-discovered diagnosis of an age-long disease. When I was a child, doctors and parents probably ignored this condition because the child looked so well, apart from the cough!
However, we need to pay attention to this condition because it is more common than we think. It affects some 40 per cent of children with chronic cough in Australia, where most of the research in PBB has been carried out. Although symptoms are usually more annoying than harmful in the short-term, research shows that if it’s left unchecked, PBB may possibly lead to damaged airways (a condition called bronchiectasis).
Thankfully, treatment ― with at least two weeks of antibiotics ― is usually successful. Yes, you didn’t read the number wrongly, two weeks of antibiotic treatment is required because in this condition, the bacteria sticks closely to the airways, so a shorter course of antibiotics often fails.
To manage this condition effectively, a doctor experienced in diagnosing PBB has to make a good diagnosis. The doctor also has to ensure that no other conditions are responsible for your child’s cough. Plus, both the doctor and the parents have to be certain that this daily phlegmy cough has lasted more than four weeks, because the decision to treat well-looking children with two weeks of antibiotics should not be taken lightly.
This article isn’t intended to be exhaustive for all causes of chronic cough. As there are other less common but more serious causes of chronic cough, be sure to consult a doctor if your child does not recover as expected. In general, if the diagnosis is still unclear, more investigations, such as a chest X-ray, may need to be performed on a child with a chronic cough.
Dr Theodric Lee, a paediatrician with a special interest in respiratory and sleep medicine, practises at Thomson Paediatric Centre (Jurong East).
Photos: iStock
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