Reactive Airway Dysfunction Syndrome - An Overview

Introduction

Lungs are the vital organs of the respiratory system located in the chest cavity, one on each side of the heart. The right lung comprises three lobes, and the left has two lobes. During breathing, the air enters the airways, moves down into the air sacs or alveoli, and reaches the lungs, where oxygen and carbon dioxide exchange occurs. Alveoli comprise a mesh of tiny blood vessels known as capillaries; they are elastic and can easily expand and contract. Infection, inflammation, or damage to the airways or lungs can lead to asthma, bronchitis (inflammation of the bronchial tubes), pneumonia (infection of the lungs), and other respiratory disorders.

Exposure to cigarette smoke, dust, chemicals, air pollutants, and other substances can make these conditions more severe and require long-term treatment. Therefore, limiting exposure to air pollution, using protective gear to avoid inhaling chemicals or allergens, and taking necessary precautions during flu seasons can help maintain respiratory health.

What Is Reactive Airway Dysfunction Syndrome?

Breathing problems of sudden onset that develop following a single exposure or repeated exposures to high levels of an irritant are known as reactive airway dysfunction syndrome. Irritants include perfumes, laundry detergents, petrol fumes, chemical spills, corrosive gas, or other substances that can cause smoke, fumes, fire, and vapors. These may lead to swelling, narrowing, and other harmful effects on the lungs' airways.

Reactive airway dysfunction syndrome (RADS) was first described in 1981 by Brooks and Lockers as nonimmunological asthma that results from exposure to an irritant gaseous substance. It is a poorly understood condition, but it is similar to asthma (a chronic lung disorder characterized by inflammation and narrowing of the airways) and is often classified as occupational asthma. However, according to research, the presentation of RADS may differ from that of true occupational asthma as it is an acute single event in most cases without a significant latency period.

What Are the Symptoms of Reactive Airway Dysfunction Syndrome?

Symptoms of reactive airway dysfunction syndrome develop rapidly, usually 24 hours after exposure to the irritant. Depending on the irritant, it manifests as bronchitis (inflammation of the bronchial tubes or airways) or ocular and mucous membrane irritation of the airways. They are similar to asthma symptoms, mild or severe, and last several months to years. If the symptoms persist for more than six months, they can become chronic or even life-threatening, especially if they are occupation-related or there is daily exposure. However, most symptoms respond well to treatment, but there may be long-term airway damage.

Some of the common symptoms of RADS include:

• Coughing.

• Wheezing (a whistling noise in the chest).

• Trouble breathing or shortness of breath.

• Chest discomfort or tightness.

• Swelling in the throat.

• Increased heart rate.

• Burning sensation in the nose and throat.

• A feeling of tearing in the throat.

• Conjunctivitis (inflammation of the conjunctiva).

Who Is at Risk of Developing Reactive Airway Dysfunction Syndrome?

People who are in certain occupations are at an increased risk of exposure to pulmonary irritants, which may cause the development of reactive airway dysfunction syndrome.

These include the following:

• Policemen.

• Cleaners.

• Firefighters.

• Hospital workers.

• Farmers.

• Emergency service workers.

• Construction workers.

• Factory workers.

How Is Reactive Airway Dysfunction Syndrome Diagnosed?

The American College of Chest Physicians criteria for the diagnosis of reactive airway dysfunction syndrome include:

• Documented absence of a preceding respiratory complaint.

• The onset of the condition occurs after a single specific exposure incident or accident.

• Exposure to a very high concentration of smoke, fumes, corrosive gas, vapors, or other substances with irritant properties.

• The onset of symptoms occurs within 24 hours of exposure and is persistent for at least three months.

• Symptoms such as cough, wheezing, and dyspnea (difficulty breathing) are stimulated by irritant exposure.

• Airflow obstruction is observed on pulmonary function tests with or without nonspecific bronchial hyper-responsiveness.

• All other pulmonary diseases are excluded.

The doctor will take the patient's complete case history, conduct a chest examination, and recommend chest X-rays, certain blood tests, investigations to check oxygen levels, and spirometry if required (a common breathing test to measure lung function). Some of the other tests include immunologic testing, allergy skin testing, pulmonary function tests, and bronchoprovocation tests.

Pathological examination in patients with reactive airway dysfunction syndrome demonstrates nonspecific inflammation with a cellular infiltrate, primarily lymphocytic, with epithelial desquamation. In some cases, the diagnosis of RADS may be confirmed after multiple follow-ups or after visiting a respiratory specialist. If symptoms of reactive airway dysfunction syndrome are observed within 24 hours of exposure to the irritant, it is recommended to consult a healthcare provider immediately, as it requires emergency treatment.

How Is Reactive Airway Dysfunction Syndrome Managed?

The treatment of reactive airway dysfunction syndrome is similar to asthma treatment. Initially, medications are prescribed to ease the symptoms. Avoiding irritants or other substances that trigger the symptoms is also necessary. The healthcare provider prescribes certain medications based on the severity of the condition and the patient's overall health.

Some of the common medications include:

• Quick-Relief Medicines: These fast-acting drugs provide quick relief after the onset of symptoms. They act by relaxing and opening up the airways. It must be kept always with the patient but taken only when necessary. If symptoms are severe, oral steroids can also be recommended.

• Inhaled Corticosteroids: These medications are inhaled directly through the nostrils, reducing the swelling or inflammation and opening up the airways. These are used when symptoms are severe or persist for a long time.

• Long-Term Medications: These drugs help relax the muscles around the airways and are taken explicitly on a schedule. It must be taken regularly and exactly as prescribed by the doctor.

• Vitamin D: Studies have shown that vitamin D's effects as a hormone have gained attention recently. It possesses regulatory effects on the immune system and assists steroids in reducing inflammation.

What Are Some of the Measures to Prevent Reactive Airway Dysfunction Syndrome?

Some of the preventive measures for reactive airway dysfunction syndrome include:

• Avoiding exposure to pulmonary irritants or substances that trigger the symptoms.

• If it is a household product, switching to alternatives is better.

• Protective gear can be used to avoid exposure to chemicals or irritants during occupation.

• Quitting smoking and avoiding exposure to secondhand smoke.

• Taking prescribed medications regularly.

• If an individual is exposed to irritants or experiences dizziness (lightheadedness), cough, difficulty breathing, or discomfort in daily activities, a healthcare provider must be consulted immediately.

Conclusion

Reactive airway dysfunction syndrome is a respiratory condition similar to asthma that usually occurs suddenly after a single high-level exposure to pulmonary irritants such as smoke, dust, fumes, chemicals, vapors, corrosive gas, etc. However, the condition currently lacks clarity due to a retrospective diagnosis following an unmeasured exposure to respiratory irritants. While there are reports of an increased number of cases from an array of causal agents, it lacks sufficient evidence on effective treatment, particularly in patients with ongoing symptoms who experience a poor quality of life. Therefore, it is recommended to stay away from irritants or discuss with the employer if it is occupation-related to improve overall health and prevent future complications.