What Is Reactive Airway Disease?

Reactive airway disease (RAD) is a general term used to describe a reaction in which the lungs' bronchial tubes overreact to an irritant, triggering wheezing and shortness of breath. While it's easy to assume that RAD is the same thing as asthma, it's simply a classification of respiratory symptoms related to any number of conditions, including asthma, chronic obstructive pulmonary disease (COPD), and certain bronchial infections.

Varying Definitions

While the term RAD is not meant to confuse people, it frequently does—in part because it was once called reactive airway dysfunction syndrome, as coined by American pulmonologist Stuart Brooks in 1985.

Reactive airway dysfunction syndrome was described as a single toxic inhalation of smoke, fumes, or corrosive gases that leads to a long-term, often chronic lung condition mimicking a severe form of COPD.

Since that time, though, the shortened reactive airway disease (RAD) has been increasingly used to describe a wide range of diseases that cause asthma-like symptoms.

The problem is that it is not a medical term, per se, and it has different definitions depending on who you speak to. Some doctors use RAD to describe diseases that cause reversible airway narrowing, while others will include COPD, which is clearly not reversible.

To add even more confusion, some—including medical professionals—will misuse RAD as a synonym for asthma.

Others contend that the term has an appropriate usage, particularly in pediatrics or emergency care.

In fact, RAD is most commonly applied when a child experiences asthma-like symptoms but is too young to undergo certain forms of diagnostic evaluation. Less commonly, it may be used by ambulance personnel to describe irritant-related breathing problems to emergency room staff before an investigation has begun.

The very non-specificity of the classification, some argue, is meant to incite clinicians to look beyond the obvious causes and explore less common (and potentially more serious) explanations for symptoms.

Reactive Airway Disease Symptoms

You could be said to have RAD if you are experiencing:

• Wheezing
• Shortness of breath
• Persistent, productive cough

This cluster of symptoms is triggered by a common physiological response, whether you have asthma, COPD, or another reactive respiratory condition.

Depending on the severity of the response, symptoms can range from mild to life-threatening.

Causes

In the broadest of terms, RAD is an asthma-like episode that develops in the absence of allergy within 24 hours of exposure to an aerosol, gas, fumes, or vapor.

It occurs when there is:

• Breathing limitation caused when the smooth muscles of the lungs are hyperresponsive, cause airways to contract and narrow
• Inflammation caused by the body's response to allergens in the lungs, which causes swelling and further narrowing of air passages
• Excessive mucus production in response to the above, which clogs the airways and tiny air sacs of the lungs (alveoli)

Again, RAD is not a diagnosis, but rather a characterization of physical symptoms. It serves only as the launching point for an investigation, the direction of which can vary based on your age, medical history, symptoms, and events leading up to the attack.

The shortlist of possible causes of RAD includes:

• Allergic bronchopulmonary aspergillosis (ABPA), a colonization of mold that triggers an immune reaction in the lung resulting in asthma-like symptoms often accompanied by the coughing up of blood
• Asthma, which can occur at any age and often runs in families, or be due to occupational exposures (e.g., in bakers, farmers, plastic fabricators, etc.)
• Bronchiectasis, a chronic lung condition differentiated by audible crackles when breathing and finger clubbing
• Bronchiolitis obliterans, a severe lung disease often affecting younger people who do not smoke
• Congestive heart failure, often accompanied by leg swelling, chest pains, and irregular heartbeat
• COPD, typically associated with long-term exposure to cigarettes or toxic fumes
• Cystic fibrosis, a congenital disease affecting children at a young age and characteristically accompanied by chronic digestive problems
• Gastroesophageal reflux disease (GERD), in which asthma-like symptoms are accompanied by chronic acid reflux
• Granutalomous lung disease, granular formations in the lungs caused by fungal or mycobacterial infections, or by immune-mediated disorders like sarcoidosis or granulomatosis with polyangiitis
• Hypersensitivity pneumonitis, an immune condition that mimics asthma in the acute phase (short term) and COPD in the chronic phase (long term)
• Pulmonary embolus, a blood clot in the lungs often occurring in people with heart disease, cancer, or who have had recent surgery
• Upper respiratory viral infection, in which asthma-like symptoms are accompanied by high fever, chills, and body aches

Diagnosis

The approach to diagnosis is as varied as the possible causes. By and large, doctors will pursue investigations based on the diagnostic clues noted in the initial exam.

These may include:

• Bronchoprovocation challenge testing and peak expiratory flow rate (PEFR) to help diagnose asthma
• Pulmonary function tests like spirometry, diffusion studies, and body plethysmography to diagnose COPD
• Imaging tests like chest X-rays, computed tomography (CT), and magnetic resonance imaging (MRI) to investigate heart disease, lung disease, or cancer
• Blood tests or cultures to detect inflammation or infection
• Skin prick and RAST blood tests to identify allergy triggers
• Lung biopsy to help evaluate suspicious tissue growths
• Antinuclear antibody (ANA) blood tests to help diagnose autoimmune disease
• CF gene mutation panel to diagnose cystic fibrosis
• Bronchoscopy, in which a viewing scope is inserted into the windpipe to determine whether acid reflux is a cause

In pediatric cases, RAD may be notated in the infant's medical records if no apparent cause is found in the early investigation. The aim of the notation is to ensure that the baby's condition is monitored until such time as more definitive diagnostic investigations can be performed.

Treatment

There are no clear treatment guidelines for reactive airway disease.

"RAD" may serve as a shorthand of symptoms for ER staff that can provide them a sense of the patient's status before arrival by ambulance. The classification can help direct rescue efforts, which may include:

• Emergency oxygen therapy
• Pulse oximetry to assess oxygen blood saturation
• Inhaled rescue bronchodilators (or intravenous types in severe cases)
• Epinephrine injections if symptoms are suggestive of potentially life-threatening allergic anaphylaxis

However, one reason why some do not favor use of the term RAD outside of this or a pediatric setting is that it suggests that it is a disease entity when it is not. This has led to suggestions that the broad spectrum of diseases that fall under the RAD umbrella may be similarly treated, which is simply not the case.

One such example was a 2011 study published in the Journal of Allergy and Asthma in which high-dose vitamin D (up to 5,000 IU per day) was said to improve symptoms of RADS in a single woman whose lungs were injured in an ammonia spillage accident. 

The problem with this is that it creates an entirely different and idiosyncratic definition for RAD—supplanting the accepted medical term chemical pneumonitis for RAD—while inferring that vitamin D offers unique and unproven properties that extend to anyone with toxic lung injury.

A Word From Verywell

There is nothing wrong or inherently misleading about being told that you or your child have restrictive airway disease. It simply suggests that something is causing breathing problems and that further investigation is needed.

You should not be told, however, that you have restrictive airway disease and provided treatment without a proper investigation (or, worse yet, no treatment at all).

If you have an acute or chronic breathing disorder that is beyond the scope of your primary care doctor, ask for a referral to a pulmonologist for further evaluation.