What is Asthma? Windpipe Wheezing and Hard to Breathe

Asthma is an immune-related disorder that results in narrowing of the airways when a susceptible person encounters certain environmental stimuli such as pollen and dust. Air flow through the windpipes to and from the lungs is therefore restricted and normal oxygenation of the blood is subsequently affected.

Although the condition is commonly referred to as wheezing, it is important to understand that wheezing is the abnormal breathing sound heard in asthmatics. It is a symptom. Wheezing can occur in other respiratory conditions as well. The constriction of the airways is usually reversible but causes great difficulty in breathing at the time of the asthma attack. If left untreated, severe asthma can cause respiratory and cardiac arrest followed by death.

How common is asthma?

Asthma Prevalence

The worldwide incidence of asthma seems to have increased within the past forty years. This is often attributed to the environmental and lifestyle changes in various countries caused by rapid industrialization. It is estimated that about 4% to 7% of the world’s population suffers from asthma. In the USA alone, more than twenty million people are thought be suffering from this disorder. Asthma affects individuals of all ages. It is one of the most common chronic ailments seen in children. Both males and females are equally susceptible.

What are the signs and symptoms?

Asthma Symptoms

Asthmatic patients usually do not show any symptoms till an asthma attack is triggered. Asthma is often related to two other allergic conditions – allergic rhinitis and atopic dermatitis (eczema) – and are collectively known as the allergic triad. The symptoms of these conditions may be present even though there are no asthma symptoms. The following symptoms are caused by the constriction of the airways (bronchioles) during an asthma attack :

• Dyspnea which is difficulty breathing
• Feeling of tightness in the chest which makes it hard to breathe
• Coughing
• Wheezing sounds during breathing (mostly during exhalation)

Many of these symptoms worsen at night time, causing patients to awaken from their sleep.

Asthma Diagnosis

Asthma is diagnosed on the basis of physical examination, medical history and lung function tests. Since the symptoms of asthma are non-specific, it is important that other causes are ruled out before arriving at a diagnosis of asthma.

• Pulmonary function tests are performed on suspected asthma patients to determine the extent of airway obstruction.
• Chest X-rays may also be done to rule out other conditions with similar symptoms.
• Allergy testing may be done in patients whose medical history suggests that asthma attacks are precipitated by certain allergens.

What happens in asthma?

Asthma Pathophysiology

The airways, specifically the bronchi and bronchioles (windpipes in common terms) leading to the lungs, are the main site of where the problem lies. A variety of inflammation-causing cells of the immune system such as TH2 cells, eosinophils, mast cells, neutrophils and CD4+ cells infiltrate the walls and the smooth muscles of the airways. These pro-inflammatory cells release chemical substances that stimulate growth of smooth muscles and fibroblasts, causing significant changes in the structure of the airways.

The proliferation of the smooth muscles narrows the airways and makes them hyper-reactive to allergens. This increased hyper-reactivity of the airway muscles to the allergens causes further constriction of the airway passages, leading to difficulty in breathing. Swelling in the already thickened airway walls and mucus build up with inflammation also contribute further to narrowing and hampers air flow to the lungs. Wheezing and complaints by the patient that they find it hard to breathe are simply symptoms of asthma.

Why does asthma occur?

Asthma Causes

Both genetic and environmental factors have been implicated in causing asthma. Genetic factors predispose an individual to developing asthma, whereas the environmental factors trigger or exacerbate the asthma attacks.

It is now accepted that asthma is caused by interactions of various genetic and environmental factors. The environmental allergens precipitate asthma attacks by activating type 2 T-helper (TH2) cells of the immune system, which then stimulate eosinophils and IgE production to mediate the allergic response.

Some individuals are born with a predisposition towards this pro-inflammatory TH2 pathway activation. Most people are tolerant towards these environmental allergens because of childhood exposures to bacterial and viral infections that trigger the TH1 pathway. The TH1 pathway suppresses the TH2 pathway and prevents allergic reactions.

Asthma Genes

Genetic factors causing asthma: A variety of pro-inflammatory genes are implicated in the pathogenesis of or susceptibility to asthma. These include genes for:

• Cytokines (interleukins-3, 4, 5, 9 and 13)
• Tumor necrosis factor-α
• IgE (immunoglobulin E)
• Granulocyte-monocyte colony-stimulating factor (GM-CSF)
• Genes involved in production of T-helper cells (both TH1 and TH2)
• The ADAM33 gene which is responsible for the production of a protein that stimulates proliferation of airway smooth muscles and fibroblasts. This gene may also be involved in the regulation of proinflammatory cytokine production.

Asthma Triggers

Environmental factors causing asthma: The environmental factors that may trigger asthma include a variety of allergens :

• Dust mites, cockroaches, pets, pollen, cigarette smoke, perfumes and smog are well known triggers of asthma attacks when due to an allergy.
• Viral infections can trigger asthma attacks in children. Some of these infectious triggers include rhinovirus, parainfluenza virus and respiratory syncytial virus (RSV). Pneumonia can also trigger asthma.
• Obesity.
• Diets low in vitamin C, vitamin E and omega-3 fatty acids have also been linked to asthma.
• Perinatal factors such as poor maternal nutrition, young maternal age, premature birth, low birth weight and lack of breastfeeding have also been implicated as causes of asthma.
• Aspirin.
• Exercise in cold and dry environment.
• Gastroesophageal reflux disease (GERD – acid reflux).

Risk of Asthma

Asthma has both genetic and environmental risk factors. Apart from the genes that predispose certain people to asthma, being female also seems to be a risk factor. In addition, an early age of onset is a risk factor for chronic recurring asthma.

Environmental risk factors include smoking (primary or secondary) and sensitivity to household dust mites. Presence of allergens like pollen and chemicals in the environment also increase the chances of triggering an asthma attack.

How is asthma treated?

Asthma Treatment

There is no cure for asthma. However, the condition can be successfully treated by using a two-pronged approach:

1. avoiding the environmental triggers of the asthma attack, and
2. taking medications for controlling the symptoms of an asthma attack.

Avoidance of triggers:

If the environmental triggering factors for an asthma attack are known, then the primary step is to avoid those factors. Dust mites should be removed from the patient’s house by steam treatment. Soft toys, carpets and other such household items can be reservoirs of mites. Therefore, these items should be discarded.

It is advisable for patients to avoid furry pets since they could be sources of mites and dander. Dehumidifiers should be used to prevent mold buildup in damp rooms. Cigarette smoke, strong perfumes, irritant fumes, cold temperatures and humid environments should be avoided. Exercise should be avoided at times when it is found to be the triggering factor.

Medication: Drugs used for the treatment of asthma consist of β2-agonists, anti-cholinergics, corticosteroids, leukotriene modifiers, mast cell stabilizers and methylxanthines. These drugs are either inhaled or taken orally. These drugs act by relaxing the airway muscles and preventing further inflammatory immune response. It may also suppress the immune system. Severe asthmatic attack (status asthmaticus) may require emergency medical treatment that is not a part of the long term management of asthma.

What is the prognosis for asthma?

Asthma Recovery and Outlook

Asthma can be controlled and treated well with medication. The prognosis for patients undergoing treatment is quite good depending on the management and whether there are major structural changes in the airways. Many of the deaths attributed to asthma attacks could have been prevented if the patients knew about the condition and had taken the steps to deal with it. Proper medical care and rapid access to an emergency room are other important factors in determining survival in status asthmaticus. Therefore, patient education is of paramount importance in managing asthma.

Dr. Ethan Lee

He is a dedicated ENT specialist, provides comprehensive and compassionate care for ear, nose, and throat concerns. His expertise guides individuals to breathe, hear, and communicate with ease, enhancing their quality of life.