Understanding Asthma: Causes, Diagnosis, And Treatment

According to the Centers for Disease Control and Prevention (CDC), asthma affects at least 1 in 12 adults and 1 in 11 children in the  U.S.¹ The World Health Organization (WHO) states that approximately 262 million people globally have asthma.²

Although researchers haven’t discovered the precise factor that causes asthma, they’ve pinned down several genetic and environmental elements. Allergens and viral infections contribute to its development, as well as premature birth, obesity, genetics, and exposure to cigarette smoke. 

Although asthma in childhood is a predominantly male disease, after age 20, the prevalence between men and women is about equal. At age 40, asthma becomes more common in women.

What is asthma?

Asthma is a chronic respiratory condition that causes your airway to swell and narrow, resulting in breathing difficulties. 

The condition may cause: 

• Coughing

• Wheezing when breathing out

• Breathlessness

• Chest tightness

• Difficulty breathing

These symptoms tend to occur more often in the early morning or at night. While the issue can resolve on its own, you may need treatment.

Asthma is a mild annoyance for some people. For others, it can be a serious issue, and severe cases could result in a potentially fatal asthma attack. 

Although doctors cannot cure asthma, they can manage its symptoms.

What is the pathophysiology of asthma?

Pathophysiology refers to how a disease affects the way your body normally functions. The word derives from the Greek words 'Pathos,' referring to suffering, and 'physiologia,' which means natural philosophy.

Our understanding of asthma’s pathophysiology has improved thanks to numerous discoveries over the past 25 years. Generally, it involves:

• General hypersensitivity (atopy)

• Hyperresponsiveness to stimuli

• Inflammation and bronchoconstriction

• Airway remodeling in severe asthmatic conditions

Generally, asthma starts with atopy, a genetic predisposition to developing antibodies against common allergens. Once your immune system notices irritants, it produces antibodies. 

Common irritants include: 

• Pollen

• Dust

• Smoke

• Workplace chemicals

• Strong odors

This is when hyperresponsiveness kicks in, inflaming and narrowing your airways. You'll notice a change in your breathing, prompting you to reach for your rescue inhaler. An inhaler contains a bronchodilator, a medicine that relaxes and expands your airways, allowing air to flow easily.

The initial allergen exposure results in your body producing allergen-specific antibodies.  Immunoglobulin E (IgE) antibodies bind to the surface of various white blood cells, such as mucosal mast cells or basophils, depending on the type of asthma. 

When you inhale an allergen, it comes into contact with mucosal mast cells. Your body reacts and releases inflammatory mediators, like prostaglandins, histamine, and leukotrienes. These cause excessive mucus production and inflammation.

This inflammation can ultimately lead to airway remodeling. This structural change hardens and thickens your airway walls and narrows your airway, further restricting your breathing. Airway remodeling also causes the mucus glands to increase in size and blood vessels to grow quickly and improperly.

As your white blood cells release substances to deal with the allergen, they cause a constriction in your lungs called bronchospasm. This makes it harder for you to breathe as your airways tighten. Normally, bronchospasms last 1–2 hours before subsiding. However, another attack might happen after 12 hours.

These symptoms make breathing more difficult and cause a persistent cough that tries to expel the mucus. 

Depending on your asthma severity, you might occasionally experience symptoms or always have them. Worsening asthma involves a more severe constriction of the airways, making breathing difficult. These attacks can be fatal.

Although asthma is typically manageable with therapy and management, airway remodeling is irreversible. Research links it to worsening symptoms and more frequent and severe attacks.³

The prevalence of asthma

Asthma affects about 25 million Americans or roughly 1 in 13. According to a CDC study, asthma affects over 20 million Americans over 18.⁴

In America, Puerto Ricans have the highest incidence of asthma, followed by Black adults. Generally, women are more likely to have asthma than men. It is the most common chronic illness in children besides dental cavities: Approximately 5.1 million children under 18 have asthma.

Risk factors and morbidity

Asthma has no single cause. Some genetic and environmental components play a role in its occurrence. These risk factors include:

• A family history of atopic diseases, such as asthma, hay fever, or eczema

• Prenatal exposure to maternal smoking

• Increasing maternal age at delivery: >30 is associated with a lower risk of asthma

• Premature birth

• Exposure to volatile chemicals, like solvents, agricultural products, and plastics

• Obesity

• Studies note that infants who contract rhinovirus or respiratory syncytial virus in early life are more likely to develop asthma.⁵

• Breastfeeding is associated with a lowered rate of wheezing until two years of age; however, it does not reduce wheezing in later childhood.

Asthma claims the lives of 11 Americans on average every day, causing 4,145 deaths in 2020.⁶ With the appropriate care and treatment, almost all fatalities are preventable. 

Asthma deaths occur five times more in adults than in children. Evidence shows that girls are less likely than boys to die from asthma, while the opposite is true for adults.⁷

Asthma-related deaths are more likely to affect Black Americans than white Americans. Black women had the highest rate of asthma fatalities when taking sex into account. In 2020, Black women had a roughly four-fold greater risk of dying from asthmatic attacks than white men. 

Diagnosis of asthma

The diagnosis of asthma extends beyond noticing the signs and symptoms. 

Peak expiratory flow (PEF) measurements and pulmonary function tests (PFTs) may be necessary to diagnose asthma. Other factors that help doctors diagnose the condition include checking your medical history, noting your response to medication, and a physical exam. 

There is no gold standard for asthma testing. Ultimately, diagnosis depends on the risk factors and consideration of alternative conditions. 

A definitive diagnosis relies on a history of your airways responding to inhalers and symptoms improving with steroids and inhaler use.

When a child or adult has a high likelihood of having asthma, doctors often begin a treatment trial, preferably with baseline lung function tests. Adults can also undergo treatment trials within a 2- to 4-week course of inhaled steroids, particularly if they have a chronic cough.

Your doctor may do a bronchodilator reversibility test to see how well your lungs work and respond to medication. A result of FEV1 >12% and >200mL from baseline can indicate asthma. 

Doctors frequently perform tests like peak flow, spirometry, and airway responsiveness on those with a moderate chance of asthma.

Spirometry

Spirometry is a helpful tool for determining lung function and diagnosing adult asthma, but it's not always conclusive. If you’re healthy during testing, normal findings do not rule out asthma. 

Based on spirometric measurements, an FEV1/FVC ratio of less than 0.75 indicates airway obstruction, meaning there is an increased likelihood of asthma. This result may also stem from diseases like COPD.

Spirometry following a therapy trial is more beneficial for people with documented airflow restriction and less useful for those whose lung function was almost normal before the trial.

Peak expiratory airflow

Doctors measure airway impedance using a peak flow meter to perform a peak expiratory flow test. While it shows variation in lung function during the day, it's not as precise as spirometry. 

To determine how your symptoms vary from morning to night, you should take measurements at least twice a day and record them in a journal. Document the highest readings from three expiratory blows each session.

Peak flow diaries are more effective for people who already have an asthma diagnosis than for an initial diagnosis; however, they can help doctors diagnose work-related asthma.

Assessment of the responsiveness of the airways (bronchoprovocation challenge test)

Bronchoprovocation testing answers whether someone really has asthma. This test separates asthma from other illnesses that doctors can mistake for asthma. These conditions include heart failure, rhinitis, gastro-oesophageal reflux, and vocal cord dysfunction.

This test is particularly useful in people with signs of asthma but normal PFTs and no response to bronchodilators. These can occur in those with: 

• Well-managed asthma

• Atypical symptoms of asthma

It can also occur in people requiring screening tests for asthma, such as scuba divers. 

This airway responsiveness test involves inhaling methacholine or mannitol to check how your airways narrow. Methacholine causes direct bronchoconstriction, and mannitol causes indirect bronchoconstriction.

An asthma diagnosis depends on the dose needed to decrease your FEV1 by 20%. 

Other testing

Doctors can also perform asthma testing through non-invasive means. These include fractional exhaled nitric oxide (FeNO) tests and sputum eosinophil measurements. 

Up to 80% of asthma patients with untreated asthma have an elevated sputum eosinophil count. This means you have more white blood cells in your phlegm than average.

A FeNO test measures the amount of nitric oxide (NO) in your breath. Your body produces higher levels of NO when inflammation is present. 

The sputum test is not a definitive diagnosis because people with a persistent cough or COPD may also have abnormally high amounts of eosinophils. However, the FeNo and sputum eosinophilia tests rarely provide false positives or negatives.

Treatment options for asthma

Understanding the best asthma remedies for immediate relief and long-term management is wise if you or a loved one has the condition. This will make it easier to manage your symptoms. 

Knowing when to call your doctor to avoid emergencies is vital. There are basically two treatment options when attempting to manage asthma symptoms. They include:

Drug interventions

Depending on your symptoms, you might need long-term therapies and quick-acting rescue medications. Some medications you can use include:

• Quick-relief or rescue inhalers

• Short-acting beta-agonists: Albuterol and levalbuterol

• Inhaled corticosteroids: Beclomethasone or budesonide

• Leukotriene receptor antagonists: Montelukast

• Oral corticosteroids: Prednisone and methylprednisolone

Long-term medication manages asthma symptoms and guards against attacks. Your airways become less sensitive to asthmatic triggers due to reduced mucus and swelling. 

Examples of these interventions include:

• Inhaling long-acting beta-agonists: Vilanterol, salmeterol, and formoterol

• Inhaling corticosteroids: Budesonide, fluticasone, beclomethasone, ciclesonide, and mometasone

• Long-acting muscarinic antagonists: Tiotropium

• Long-acting beta-agonists: Formoterol or salmeterol

• Combined inhalation medications containing a long-acting beta-agonist and an inhaled corticosteroid

• Leukotriene modifiers reduce swelling by relaxing the bronchial smooth muscle surrounding your airways

• Chromones, such as cromolyn, although these have limited use and benefit

• Biologics: Omalizumab or tezepelumab

• Theophylline

• Long-acting bronchodilators

Lifestyle interventions

An essential part of managing asthma is lifestyle interventions. You should use these methods in addition to medication: 

• Avoid exposure to tobacco smoke

• Regular physical activity

• Maintain a healthy weight

• Eat a healthy diet

• Avoid medications that trigger or worsen asthma attacks

• Learn proper stress management strategies

• Quit smoking

• Learn more about the condition

• Avoid allergens

The role of patient self-management in managing asthma symptoms

Research shows that potentially preventable hospitalizations for asthma in children cost $278.1 million. In addition, many asthma-related deaths are avoidable.⁸

Taking charge of your asthma and improving your symptom management practices will ensure you lead a fuller and more productive life. Increasing your knowledge about asthma and working with your doctor is vital in symptom management.

Making changes while following medical specialists' recommendations constitutes asthma self-management. Learning how to respond appropriately when the first symptoms of an asthma attack occur is crucial.

You can develop self-management skills through various education programs offered by reputable organizations, as the American Lung Association. This enables you to react to multiple symptoms appropriately and avoid life-threatening situations.

The prognosis for people with asthma and strategies for improving outcomes

Generally, most people with asthma have relatively good disease control methods and can lead normal lives, only occasionally needing small quantities of medicine for flare-ups. 

Only a small group struggle with severe or "difficult-to-control" asthmatic symptoms, which are often triggered at work or school. This group is also susceptible to the adverse side effects of pharmacologic treatment, especially those related to high doses of oral corticosteroids. However, the life expectancy of people with controlled asthma is similar to the general population.

People with asthma who are vulnerable to inhaling tobacco smoke or who smoke need special attention because smoking tends to exacerbate asthma. Even the most effective anti-asthma medications struggle to reduce smoke-related flare-ups.

This condition's most significant long-term effect is airway remodeling, which does not respond well to treatment, if at all. 

Asthma requires constant monitoring and treatment, not just when symptoms appear. Some of the most effective strategies to improve asthma attack outcomes include:

• Recognizing asthma attacks early and using medications to mitigate them

• Taking preventative medication as prescribed by your doctor

• Keeping an eye out for indicators that your asthma is getting worse

• Understanding what to do if your asthma worsens

When to visit your doctor

You should visit your doctor at least once yearly or more regularly if asthma symptoms persist even after trying medications. You must see your doctor if:

• You feel too weak to carry out everyday tasks

• Your asthma frequently wakes you up at night

• You become more reliant on your rescue inhaler

• You have a persistent cough or wheeze

It's also crucial to educate yourself on your condition and its symptoms. The more informed you are, the more proactive steps you may take to enhance your lung health and general well-being. While visiting your doctor, consult them about:

• The kind of asthma you have

• Symptoms and what causes them

• What daily medications work best for you

• The best asthma attack treatment strategy for your condition

The lowdown

Asthma makes breathing challenging due to inflammation of the airways. Children and adults can experience various symptoms of asthma and different types of conditions.

Asthma is treatable with a variety of drugs. The most popular therapies are bronchodilators, which you can use long-term to manage symptoms or short-term to manage an asthma attack.

Altering your way of life may also lessen asthma attacks. This entails healthy eating, becoming active, and properly managing stress. Understanding your asthma, its triggers, and the appropriate options to treat and manage your condition can be life-saving.