Asthma

What is Asthma?

Asthma is a chronic disease that affects millions of Americans and is increasing in incidence. Asthma is a syndrome that is comprised of reversible airflow obstruction that leads to breathing difficulty and shortness of breath. It is also associated with airway inflammation that is caused by various triggers including infections and environmental exposures, obesity and allergens. Some patients have a genetic predisposition to asthma with multiple family members being affected by the disease. Asthma is known as a heterogeneous condition, which means that it varies in what is driving it, even if the symptoms are the same.

About Severe Asthma

Although asthma can be easily treated in most patients, 10 percent of patients have severe asthma that causes debilitating disease. Asthma that is not well controlled can be fatal given exposure to triggers. The triggers cause blockage of the airway with mucous, and spasms of the muscles around the airways with closure of the bronchial tubes, resulting in an inability to breathe.

People with symptoms occurring at least 5-6 times a week and a couple of times at night a month are more at risk for a fatal asthma attack. Everyone is different, so it’s important for you to know when your asthma is flaring, which you can tell by your daily peak flow meter reading and whether you are still having tightness even after using your rescue inhaler.

Asthma Symptoms, Risks, and Triggers

Symptoms of asthma include:

• Shortness of breath
• Chest tightness
• Wheezing
• Chronic cough, can be dry or produce mucous

Common asthma triggers include:

• Viral infections
• Allergies, such as ragweed and pollen, aspirin, animal dander, or dust
• Chemical exposures, such as cleaning with bleach in a non-ventilated area
• Acid reflux (heartburn can spill chemicals from the gastrointestinal tract into airway)
• Smoking
• Cold air, during winter or from air conditioning
• Exercise
• Stress
• Obesity

People at risk for asthma often have a family history of asthma but it can occur in patients with any family history of the disease. Although it was previously thought that the onset of asthma only occurred in childhood, we now know that there are patients for whom asthma starts in adulthood. In fact, patients with asthma that starts in adulthood tend to have more severe disease that does not respond as well to treatment. Asthma is more common in those who have a history of allergies (seasonal) or atopy (immediate allergic reactions).

When asthma starts in childhood it may resolve in the late teens and early 20s. Patients will report that they have “grown out" of their asthma. However, in some cases, there is a period of minimal asthma symptoms as a young adult but a recurrence of asthma later in life.  Therefore, patients that “grow out of their asthma” must recognize the possibility of a recurrence and pay attention to any asthma symptoms that return later in life and should seek treatment if this occurs. While boys are more likely to have asthma during childhood, more females have asthma as adults.

Types of Asthma

There are several different types of asthma with varying causes and degrees of severity. The different types of asthma are described as phenotypes, which are the characteristics of a disease that can be observed (measured using tests). These phenotypes are produced by the interaction of a person's genetic predisposition and the environmental triggers that cause the disease to occur. The asthma phenotypes include:    

• Clinical phenotypes: Asthma caused by obesity or worsened by obesity, asthma that is associated with frequent attacks called exacerbations, adult onset asthma and asthma that is associated with fixed obstruction (the obstruction in airflow does not reverse with albuterol).

• Pathologic phenotypes: Asthma that is associated with increased numbers of various cells associated with inflammation such as eosinophilic asthma (caused by high eosinophils) and non-eosinophilic asthma (asthma is driven by cells other than eosinophils such as neutrophils).
• Phenotypes caused by specific triggers: These triggers include allergic asthma, exercise induced asthma, occupational asthma and asthma made worse by aspirins/non steroids and anti-inflammatory drugs like ibuprofen.

Asthma can vary in severity from person to person, regardless of the type of asthma that you have. The severity of asthma ranges from mild to severe as described below. The severity of your asthma can vary over time and does not stay the same for all individuals throughout the course of their disease. Some patients always have mild asthma, but some experience a progression of their disease and develop severe asthma over time.

• Mild intermittent asthma: Intermittent means that the asthma symptoms do not occur on a consistent basis and an individual can go through long periods without any symptoms. The majority of patients fall into this category. Includes wheezing once or twice a week. Patients with mild intermittent asthma rarely wake up at night. This type of asthma requires a minimal amount of medication and is generally easy to control. It can occur during various seasons of the year, with exercise and exposure to cold air, or with upper respiratory infections.
• Mild persistent asthma: Coughing, wheezing, and chest tightness 3 to 6 times a week. Patients may wake up at night coughing or having trouble breathing a few times a month. On a day-to-day basis, your peak flow meter (an at-home device to measure your lung function) will drop more than 20 percent. Most patients with mild persistent asthma require a low dose of asthma medications every day to keep their asthma under control.
• Moderate persistent asthma: Patients report daily symptoms of coughing, wheezing, and chest tightness. The asthma symptoms cause night time awakening more than 5 times a month. Peak flow meter reading is in the 60-80 percent range. Patients with moderate disease will definitely require medications on a daily basis for their asthma.
• Severe persistent asthma: About 10 percent of asthmatics fall into this group. These patients experience continuous symptoms of coughing, wheezing, shortness of breath and chest tightness. Patients report walking up regularly at night due to asthma. Peak flow meter reading is often less than 60 percent. Patients with severe asthma bear the burden of the disease more than any other group.  These patients suffer significantly with asthma symptoms, must take multiple medications for asthma on a daily basis and still continue to have symptoms (remain uncontrolled).  You still have severe asthma if you need multiple medications to maintain asthma control. 

Conditions That Make Asthma Worse

There are also other conditions that can make asthma worse, including gastroesophageal reflux disease, obstructive sleep apnea, vocal cord disorders (such as vocal cord dysfunction), smoking, anxiety or depression, allergic rhinitis/sinusitis, nasal polyps, menstruation and bronchiectasis (a condition that is associated with abnormally large bronchial tubes). These other conditions are called comorbidities.

The Importance of Controlling Your Asthma

Regardless of the type or severity of asthma you have, your physician should focus on controlling it. You cannot control the type or severity of asthma you have BUT you can focus on achieving control of your disease.

Uncontrolled asthma is defined as:

• Poor symptom control OR
• More than two exacerbations/year (attacks of asthma that require treatment with oral steroids like prednisone or require you to go to urgent care/ER or hospital for your asthma) OR
• At least one hospitalization or ICU stay per year OR
• Low lung function (<80% FEV1 – the amount of air that you can blow out of your lungs in one second)

Achieving asthma control is the central focus in the management of patients with asthma. Your goal should be to be able to live a productive and symptom-free life with asthma.

More Information and Patient Resources

For more information about asthma diagnosis and treatment at the University of Michigan, visit the Asthma Diagnosis and Treatment page.

For asthma patient resources, visit the Learn About Asthma section of our Care Guides website, a collection of resources approved by Michigan Medicine physicians.

Make an Appointment

To schedule an appointment to discuss yours or a patient’s need for asthma treatment:

For patients: Call our patient call center at 888-287-1084.

For referring physicians: Call M-Line at 800-962-3555, 24 hours a day.